CN113160329A - Coding plane target for camera calibration and decoding method thereof - Google Patents

Abstract

The invention discloses a coding plane target for camera calibration and a decoding method thereof, wherein the coding plane target comprises a coding checkerboard formed by alternating parallelogram coding units and parallelogram non-coding units, and the coding plane target takes the intersection points of the parallelogram coding units connected by any opposite angles as the calibration angular points of the coding plane target; each parallelogram coding unit in the coding plane target is provided with a coding pattern, and the coding pattern comprises a positioning pattern, an orientation pattern and a coding mark pattern; the decoding method of the coding plane target can quickly and accurately obtain the matching relation of the calibration corner sub-pixel coordinates, the corresponding calibration corner coding serial number and the corresponding calibration corner target coordinates on the coding plane target in the image through a digital image processing method; the coding plane target and the decoding method thereof provided by the invention can be used in the fields of camera internal and external parameter calibration and the like.

Description

Coding plane target for camera calibration and decoding method thereof

Technical Field

The invention relates to the field of camera calibration in the field of computer vision, in particular to a coding plane target for camera calibration and a decoding method thereof, which are used for monocular camera calibration, binocular camera calibration and multi-view vision system calibration.

Background

Computer vision is widely applied to the fields of control engineering, optics, measurement and the like, the primary and fundamental problem to be solved by the computer vision is camera calibration, and the camera calibration is a big difficulty in the research of computer vision measurement technology; the final purpose is to solve the internal and external parameters of the camera and find the corresponding relation between the pixel coordinate and the world coordinate; camera calibration techniques have therefore received much attention and have also been rapidly developed.

In order to complete the calibration of the camera, the calibration needs to be realized through a calibration target, for example, a camera calibration algorithm based on radial constraint proposed by Roger Tsai in 1896, the algorithm is based on a three-dimensional target, and although the 3D three-dimensional target can realize the calibration of the camera and solve the internal and external parameters of the camera, the 3D three-dimensional target has a large volume, lacks certain flexibility and is not easy to move; zhangyingyou (Z.Y Zhang) provided a camera calibration algorithm based on a planar target in 1999, and the calibration process becomes more flexible by using the planar target with a relatively simple structure, but the planar target does not contain any coding and directional information, and in the actual calibration process, the camera often cannot shoot a complete target image, and at the moment, the camera calibration cannot be carried out by using the traditional planar checkerboard target which does not contain coding information.

Disclosure of Invention

The invention aims to overcome the defects of the prior art and provides a coding plane target for camera calibration and a decoding method thereof, which can give a determined and unique coding number to each calibration angular point in the coding plane target, so that high-precision homonymous point matching can be still completed even if the complete coding plane target cannot be shot in the multi-target camera calibration process; in addition, each parallelogram coding unit in the coding plane target contains respective coding information and is independent, and compared with a directional target, the coding plane target provided by the invention has stronger robustness in the application of camera calibration.

In order to realize the effect, the invention adopts the technical scheme that: providing a coding plane target for calibrating internal and external parameters of a camera, wherein the coding plane target is formed by a coding checkerboard which is formed by alternating parallelogram coding units and parallelogram non-coding units, the coding plane target takes the intersection points of the parallelogram coding units which are connected with any opposite angles as the calibration angular points of the coding plane target, the coding plane target comprises M rows and N columns of calibration angular points altogether, and M and N are positive integers; the interior of each parallelogram coding unit in the coding plane target is provided with a coding pattern, the coding pattern comprises a positioning pattern, an orientation pattern and a coding mark pattern, and the coding mark pattern consists of a plurality of coding unit patterns; the orientation pattern and the positioning pattern are used for judging the rotation direction of the coded plane target; the coding mark pattern is used for coding each calibration corner point in the coding plane target.

The positioning pattern, the orientation pattern and the coding unit pattern inside each parallelogram coding unit in the coding plane target are not overlapped and not communicated.

All parallelogram coding units and parallelogram non-coding units in the coding plane target are parallelograms with the length of a and the width of b, and a and b are both larger than zero; the acute angle in the parallelogram-shaped coding unit is lambda, and if the parallelogram-shaped coding unit is rectangular in particular, lambda is 90 degrees.

Arbitrarily take one of the encoding plane targetsMarking the parallelogram coding unit as a coding plane target vector determination coding unit gamma_vArbitrarily taking a coding plane target vector to determine a coding unit gamma_vOne vertex of the vector determination coding unit is marked as a first vertex o ″ of the vector determination coding unit₁Determining a coding unit gamma in the coding plane target vector_vWherein the intersections form a vector defining a first vertex o ″' of the coding unit₁Any one edge of the first edge is marked as a vector to determine first edge Ν of the coding unit_v1Determining the first edge Ν of the coding unit in the vector_v1Upward orientation amount determination encoding unit Γ_vThe vertex of (a) is marked as the first point o' on the first side of the vector-determined coding unit₂Wherein the vector determines a first point o' on a first side of the coding unit₂And vector determines the first vertex o ″ "of the coding unit₁Are 2 points which are not coincident with each other, and the vector is recorded

To specify a vector

And the positional relationship of the positioning pattern and the orientation pattern in each parallelogram coding unit within the coding plane target is as follows: the direction and the prescribed vector pointing from the center of mass of the orientation pattern to the center of mass of the orientation pattern in the same parallelogram coding unit

Are in the same direction;

marking the plane where the coding plane target is as a target plane P_tDetermining the first vertex o' of the coding unit by the vector₁Making a prescribed vector for the starting point

The unit vector in the same direction is denoted as the 1 st predetermined unit vector

When the person looks at the target plane P_tThen, the first vertex o' of the coding unit is determined by the vector₁Is a center of rotationAt the target plane P_tDefining the 1 st unit vector

Counterclockwise rotation by an angle beta '(0 DEG < beta' < 90 DEG) to obtain a 2 nd prescribed unit vector

Determining the first vertex o' of the coding unit in space as a vector₁As a starting point, an

The unit vectors with the same direction are recorded as positive vectors

Determining a coding unit gamma by using a coding plane target vector_vUpper distance coding plane target vector determination coding unit gamma_vThe two nearest vertexes of the orientation pattern in (1) are respectively marked as the 1 st temporary vertex o ″₃And the 2 nd temporary vertex o ″₄(ii) a If it is

Direction of the resulting vector and the forward vector

Are in the same direction, they will be recorded as vectors

Auxiliary vector

If it is

Direction of the resulting vector and the forward vector

Are in the same direction, then vector will be generated

Is recorded as an auxiliary vector

The positioning pattern and the orientation pattern in each parallelogram coding unit in the coding plane target are in the following position relation, the positioning pattern and the orientation pattern of the same parallelogram coding unit are both inside the corresponding parallelogram coding unit, and the mass center of the positioning pattern and the mass center of the orientation pattern in the same parallelogram coding unit are both near the mass center of the corresponding parallelogram coding unit;

the position relationship between the positioning pattern and the orientation pattern in each parallelogram coding unit in the coding plane target is as follows, the direction pointing from the orientation pattern centroid to the positioning pattern centroid in the same parallelogram coding unit and the specified vector

Are in the same direction;

the sizes of a plurality of coding unit patterns in the same parallelogram coding unit in the coding plane target can be different from each other;

each parallelogram coding unit and the positioning pattern and the coding unit pattern inside the parallelogram coding unit in the coding plane target satisfy the following relations: in the same parallelogram coding unit, the contour length of each coding unit pattern is smaller than that of the positioning pattern, and the contour length of the positioning pattern is smaller than (2a +2 b);

the background colors of all the parallelogram coding units in the coding plane target are the same, and the background colors of all the parallelogram coding units in the coding plane target are marked as color 1; the colors of all the parallelogram non-coding units in the coding plane target are the same, and the colors of all the parallelogram non-coding units in the coding plane target are marked as color 2;

the background color (i.e. color 1) of all parallelogram coding units in the coding plane target is obviously different from the color (i.e. color 2) of all parallelogram non-coding units;

the colors of all the positioning patterns and all the orientation patterns contained in all the parallelogram coding units in the coding plane target are the same, the colors of all the positioning patterns and all the orientation patterns contained in all the parallelogram coding units in the coding plane target are marked as color 3, and the color 3 is obviously different from the color 1;

the color of all coding unit patterns contained in all parallelogram coding units in the coding plane target is the same as color 1 or the same as color 3;

the positioning pattern inside each parallelogram coding unit in the coding plane target is a solid circle, the orientation pattern is a circular ring, and the coding unit patterns are all solid circles;

the connected domain with the color of 1 in each parallelogram coding unit in the coding plane target has the following characteristics that 2 connected domains with the color of 1 are contained in the same parallelogram coding unit, and the area of the connected domain with the color of 1 closest to the centroid of the directional pattern is smaller than the area of the connected domain with the color of 1 in the other parallelogram coding unit;

the areas of the positioning patterns contained in different parallelogram coding units in the coding plane target can be the same or different; the area sizes of the orientation patterns contained in different parallelogram coding units in the coding plane target can be the same or different; the areas of the coding unit patterns contained in different parallelogram coding units in the coding plane target can be the same or different;

the coding unit pattern of each parallelogram coding unit in the coding plane target has the following characteristics: in the same parallelogram coding unit, the position and the color of a coding unit pattern are determined by a non-unique coding method of each calibration corner point in a coding plane target;

the steps of decoding each calibration corner point in the coding plane target by using a digital image processing method are as follows:

step 1, inputting basic information of a coding plane target placed in a space, namely the coding plane target in the space comprises M rows multiplied by N columns of calibration angular points, and the coding number of an initial parallelogram coding unit of the coding plane target is z_vThe number phi of the calibration corner points in 4 vertexes of the 1 st parallelogram coding unit in the 1 st line on the coding plane target_p(ii) a Shooting the coding plane target in the space through a camera, thereby obtaining an image of the coding plane target, wherein the coding plane target image comprises the complete or local coding plane target;

step 2, carrying out 8-bit gray level processing on the coding target image, and recording the obtained image as a coding plane target gray level image P₁(ii) a Wherein, the planar target gray image P is coded₁Is an 8-bit gray scale map;

step 3, establishing a pixel coordinate system for calibrating the angular point, and encoding a plane target gray image P₁In the method, a checkerboard corner extraction algorithm based on growth is utilized to extract a coding plane target gray image P₁The method comprises the steps of (1) merging a sub-pixel coordinate set of m rows multiplied by n columns of calibration angular points with the largest number of calibration angular points into a calibration angular point sub-pixel coordinate set Q, and marking a polygon surrounded by the outermost angular points (namely the 1 st row calibration angular point, the 1 st column calibration angular point, the m rows of calibration angular points and the n columns of calibration angular points) in the m rows multiplied by n columns of calibration angular point sub-pixel coordinate set as a maximum calibration angular point number polygon L; wherein, the coded plane target gray image P after the angular point extraction₁No change occurred;

step 4, in the said coded plane target gray image P₁In the method, the gray values of all the pixel points in the maximum calibration corner point polygon L are kept unchanged by using a digital image processing method, the gray values of all the pixel points except the maximum calibration corner point polygon L are assigned to be 255, and the gray image P of the coding plane target is assigned₁The image obtained by the processing is recorded as a gray image P without a complex background target₁′；

Step 5, aiming at the gray image P of the target without the complex background₁' binarization processing is carried out, and a target gray level image P without complex background is obtained₁' the image obtained by binarization processing is marked as a binarized image P without a complex background target₂(ii) a Make the target binarized image P without complex background₂The background color of the middle parallelogram coding unit is changed into black, the colors of the background color of the parallelogram non-coding unit, the positioning pattern and the orientation pattern are all changed into white, and the color of the coding mark pattern can be white or black according to the coding rule;

6, according to the gray image P of the coded plane target₁The number of m rows multiplied by n columns of calibration angular points is contained in the extracted maximum calibration angular point number polygon L, and the number mu of parallelogram coding units contained in the maximum calibration angular point number polygon L is determined, wherein m, n and mu are integers;

this step can be divided into the following cases:

case 1, when m and n are both odd numbers, or m and n are odd, even, the number μ (μ is an integer) of parallelogram coding units contained in the polygon L can be calculated by formula (1);

μ＝(m-1)(n-1)/2 (1)

then step 7 is executed;

case 2, if m and n are even numbers, the estimated number μ '(μ' is an integer) of parallelogram coding units contained in the polygon L can be calculated by formula (2);

μ′＝[(m-1)(n-1)+1]/2 (2)

at this time, the number mu of the parallelogram coding units actually contained in the polygon L satisfies mu ≦ mu';

step 7, setting a parallelogram coding unit number judgment threshold value L'; target binary image P without complex background₂Performing black connected domain corrosion treatment to ensure that no complex background target binaryzation image P₂All the parallelogram coding units are disconnected at the diagonal positions, and the complex background-free target binary image P is obtained₂The image obtained by the processing is marked as a target binaryzation corrosion image P'₂(ii) a Wherein, the binary image P of the target without complex background₂When black connected domain corrosion treatment is carried out, the following conditions are satisfied:

(1) each parallelogram coding unit in the polygon L with the maximum number of the angle points satisfies the following conditions: the white connected domain of the orientation circle, the white connected domain of the positioning ring, the black connected domain of the center of the positioning ring and the white connected domain of the coding mark pattern in the parallelogram coding unit are kept complete;

(2) each parallelogram coding unit in the maximum-calibration large-angle point number polygon L meets the following requirements: the connected domains of the orientation pattern, the positioning pattern and the coding mark pattern in the parallelogram coding unit are not communicated with each other;

(3) each parallelogram coding unit in the polygon L with the maximum number of the angle points satisfies the following conditions: the orientation pattern, the positioning pattern and the coding mark pattern in the parallelogram coding unit are all positioned in the background of the parallelogram coding unit;

binarizing corrosion image P 'at target'₂Searching mu ' maximum black connected domains, and calculating the average value χ ' of pixel points contained in the first mu ' -1 maximum black connected domains;

marking the minimum black connected domain in the mu' maximum black connected domains in the polygon L as the tail end black connected domain, and calculating the pixel point chi contained in the tail end black connected domain_mJudging according to a formula (3);

(1) if L ' is less than or equal to L ', the polygon L actually comprises mu ' parallelogram coding units, and the value of mu ' is assigned to mu, and the value of mu is equal to mu '; and step 8 is executed;

(2) if L ' > L ', the polygon L actually contains μ ' -1 parallelogram coding units, and a value of μ ' -1 is assigned to μ, where μ is μ ' -1; and step 8 is executed;

step 8, finding binaryzation corrosion image P 'in target'₂And the mu maximum black connected domains in the image are respectively marked as grid connected domains omega₁Grid connected domain omega₂…, grid connected domain omega_μTaking an integerA variable i is given an initial value i which is 1;

binarizing corrosion image P 'at target'₂Calculating the square connected domain omega in the above steps_iPixel coordinate of centroid (x)_i,y_i)_iAnd re-assigning i +1 to i, and continuing to execute the step until i is greater than mu, thereby obtaining a target binary corrosion image P'₂Upper square connected domain omega₁Grid connected domain omega₂…, grid connected domain omega_μCentroid pixel coordinate (x)₁,y₁)₁、(x₂,y₂)₂、…、(x_μ,y_μ)_μAnd will be (x)₁,y₁)₁、(x₂,y₂)₂、…、(x_μ,y_μ)_μSequentially serving as a 1 st element, a 2 nd element, … and a mu th element in a parallelogram coding unit centroid pixel coordinate set A;

step 9, assigning an initial value i to the integer variable i again, wherein the initial value i is 1;

binarizing corrosion image P 'at target'₂In (1), calculating the distance grid connected domain omega_iCentroid pixel coordinate value (x)_i,y_i)_iThe nearest black connected domain is recorded as a target binary corrosion image P'₂Of (1) ring center connected region omega'_i(ii) a Assigning i +1 to i again, and continuing to execute the step until i is greater than mu; thus obtaining target binaryzation corrosion images P'₂Of (1) ring center connected region omega'₁And omega 'of circular ring center connected region'₂…, ring center connected region omega'_μ；

Step 10, assigning an initial value i to the integer variable i again, wherein the initial value i is 1;

binarizing corrosion image P 'at target'₂In (1), calculating the distance grid connected domain omega_iCentroid pixel coordinate value (x)_i,y_i)_iThe nearest black connected domain is recorded as a target binary corrosion image P'₂Of (1) ring center connected region omega'_i(ii) a The step is continuously executed after i +1 is reassigned to i until i > mu(ii) a Thus obtaining target binaryzation corrosion images P'₂Of (1) ring center connected region omega'₁And omega 'of circular ring center connected region'₂…, ring center connected region omega'_μ；

The initial value i is given to the integer variable i again as 1;

binarizing corrosion image P 'at target'₂In (1), calculating the target binaryzation corrosion image P'₂Of (1) ring center connected region omega'_iCentroid pixel coordinate o ″)_d,i(x″_d,i,y″_d,i) Assigning i +1 to i again and continuing to execute the step until i is greater than mu; obtaining a target binaryzation corrosion image P'₂Of (1) ring center connected region omega'₁And omega 'of circular ring center connected region'₂…, ring center connected region omega'_μCentroid pixel coordinate o ″)_d,1(x″_d,1,y″_d,1)、o″_d,2(x″_d,2,y″_d,2)、…、o″_d,μ(x″_d,μ,y″_d,μ) And will o ″)_d,1(x″_d,1,y″_d,1)、o″_d,2(x″_d,2,y″_d,2)、…、o″_d,μ(x″_d,μ,y″_d,μ) Sequentially serving as a 1 st element, a 2 nd element, … and a mu th element in the circular ring centroid pixel coordinate set B;

step 11, binarizing the corrosion image P 'on the target'₂In, will remove square connected domain omega₁Grid connected domain omega₂…, grid connected domain omega_μAnd a circular ring center connected region omega'₁And omega 'of circular ring center connected region'₂…, ring center connected region omega'_μThe gray values of the other black connected domains are all assigned to be 255, and the target is subjected to binarization to form a corrosion image P'₂The image obtained by the processing is recorded as a decoded binary image P₃；

Step 12, taking an integer variable zeta, and giving an initial value zeta as 1;

step 13, removing the complex background except the Zeta th parallelogram coding unit to obtain the Zeta th no-complexUnit binary image E with miscellaneous background_ζ；

In this step, the zeta unit binary image E without complex background is obtained_ζThe method comprises the following specific steps:

step 13.1, decoding the binary image P₃Copying and backing up, and recording the copied image as the zeta-th backup binary image P_ζ,4；

Step 13.2, backup binarization image P at the zeta th_ζ,4Taking the Zeth centroid pixel coordinate value (x) in the centroid pixel coordinate set A of the parallelogram coding unit_ζ,y_ζ)_ζFinding out the pixel coordinate value (x) of distance centroid in the calibration corner point set Q_ζ,y_ζ)_ζPixel coordinate values of the nearest 4 calibration corner points, and setting the pixel coordinate values of the 4 calibration corner points in the ζ -th backup binary image P_ζ,4The corresponding 4 pixel points are respectively marked as C ″)_ζ,1(x″_ζ,1,y″_ζ,1)、C″_ζ,2(x″_ζ,2,y″_ζ,2)、C″_ζ,3(x″_ζ,3,y″_ζ,3)、C″_ζ,4(x″_ζ,4,y″_ζ,4) (ii) a And taking the 4 pixel points as a zeta-th calibration corner point quadrangle S_ζAnd connecting the 4 vertexes to form a zeta-th calibration corner point quadrangle S_ζ；

Step 13.3, finding out the Zeth centroid pixel coordinate value (x) in the centroid pixel coordinate set A of the parallelogram coding unit from the circular ring centroid pixel coordinate set B_ζ,y_ζ)_ζThe corresponding zeta th ring centroid pixel coordinate value (x ″)_d,ζ,y″_d,ζ)；

Step 13.4, backup binarization image P at the zeta th_ζ,4In the method, the coordinate value (x ″) of the pixel of the center of mass of the ring is searched_d,ζ,y″_d,ζ) The nearest white connected domain, and the gray value of the white connected domain is assigned to be 0;

step 13.5, backup binarization image P at the zeta th_ζ,4In the above, the Zeta th calibration corner point quadrangle S_ζAll except imagesThe gray values of the pixel points are all assigned to be 255, and the zeta-th calibration corner point quadrangle S_ζKeeping the gray values of all internal pixel points unchanged, and marking the obtained image as the zeta-th unit binary image E without complex background_ζ；

Step 14, binarizing the image E in the zeta th unit without complex background_ζSearching for a calibration angular point of the zeta-th parallelogram coding unit, and determining a coding region corresponding to the calibration angular point;

in this step, the specific method for finding the calibration corner point of the ζ -th parallelogram coding unit includes:

step 14.1, binarizing the image E in the zeta th unit without complex background_ζIn the binary image, the maximum black connected domain is searched and marked as the zeta th unit binary image without complex background_ζMaximum black connected component Ω in_ζ,E(ii) a Extracting the Zeth unit binary image E without complex background_ζMaximum black connected component Ω in_ζ,EAnd is recorded as a centroid pixel coordinate value of (x)_ζ,y_ζ)_ζOf a parallelogram-shaped coding unit D_ζ；

Step 14.2, the coordinates of the centroid pixel are the value (x)_ζ,y_ζ)_ζOf a parallelogram-shaped coding unit D_ζIn the method, the number of pixel points included in each contour is counted, wherein the contour including the second most pixel points is the unit binary image E without the complex background at the zeta th_ζThe centroid pixel coordinate value of (x)_ζ,y_ζ)_ζIn a parallelogram coding unit of (2) an outline G of a positioning circle_ζCalculating the positioning circle profile G_ζAnd is recorded as a unit binary image E without complex background at the zeta th position_ζThe centroid pixel coordinate value of (x)_ζ,y_ζ)_ζLocate circle centroid pixel coordinate o 'in parallelogram coding unit of (1)'_l,ζ(x′_l,ζ,y′_l,ζ)；

Step 14.3, coordinate of mass center is (x)_ζ,y_ζ)_ζOf a parallelogram-shaped coding unit D_ζIn (1), the 2 contours with the largest number of pixels are removed, and the remaining k_ζ(wherein κ_ζ0,1,2, 3.) contours, classified as follows:

case 1, if κ_ζIf 0, go to step 14.6;

case 2 if κ_ζNot equal to 0, then this κ_ζThe contour is the unit binary image E without complex background at the zeta th_ζThe centroid pixel coordinate value of (x)_ζ,y_ζ)_ζThe coded mark circle contour in the parallelogram coding unit is recorded as the coded mark circle contour

Coded marker circle profile

Coded marker circle profile

Step 14.4, assigning the initial value i to the integer variable i again, wherein the initial value i is 1;

step 14.5, binarizing the image E in the zeta th unit without complex background_ζIn, calculating the circular contour of the code mark

Centroid pixel coordinates of

This step continues after i +1 is reassigned to i until i > κ_ζAnd finishing, obtaining the coordinate value of the centroid pixel as (x)_ζ,y_ζ)_ζCoded flag circle contour in parallelogram coding unit of

Coded marker circle profile

Coded marker circle profile

Centroid pixel coordinates of

Step 14.6, binarizing the image E in the zeta th unit without complex background_ζThe pixel coordinate value is (x ″)_d,ζ,y″_d,ζ) The pixel point is marked as the coordinate value of the centroid pixel as (x)_ζ,y_ζ)_ζOf parallelogram-shaped coding units of (2) oriented circular ring centroid o'_d,ζ(x′_d,ζ,y′_d,ζ) (ii) a And binarizing the image E at the ζth unit without complex background_ζThe pixel coordinate values are (x ″)_ζ,1,y″_ζ,1)、(x″_ζ,2,y″_ζ,2)、(x″_ζ,3,y″_ζ,3)、(x″_ζ,4,y″_ζ,4) And 4 pixel points are recorded as C'_ζ,1(x′_ζ,1,y′_ζ,1)、C′_ζ,2(x′_ζ,2,y′_ζ,2)、C′_ζ,3(x′_ζ,3,y′_ζ,3)、C′_ζ,4(x′_ζ,4,y′_ζ,4)；

Step 14.7, binarizing the image E in the zeta th unit without complex background_ζUpper, get C_ζ,1(x_ζ,1,y_ζ,1)、C_ζ,2(x_ζ,2,y_ζ,2)、C_ζ,3(x_ζ,3,y_ζ,3)、C_ζ,4(x_ζ,4,y_ζ,4) Respectively expressed in coordinates of centroid as (x)_ζ,y_ζ)_ζThe pixel coordinates of the calibration corner points of the No. 1 coding region, the No. 3 coding region, the No. 4 coding region and the No. 6 coding region in the parallelogram coding unit; the centroid pixel coordinate value is (x)_ζ,y_ζ)_ζOfDirection vectors in a parallelogram coding unit

Can be derived from formula (4) while recording through the centroid o 'of the positioning circle'_l,ζAnd a directional ring centroid o'_d,ζIs a straight line of_ζ,3；

Step 14.8, binarizing the image E in the zeta th unit without complex background_ζLast, 4 pixel points C'_ζ,1(x′_ζ,1,y′_ζ,1)、C′_ζ,2(x′_ζ,2,y′_ζ,2)、C′_ζ,3(x′_ζ,3,y′_ζ,3)、C′_ζ,4(x′_ζ,4,y′_ζ,4) Medium-distance positioning circle center of mass o'_l,ζ(x′_l,ζ,y′_l,ζ) The nearest 2 pixels are respectively marked as C_ζ,1min(x_ζ,1min,y_ζ,1min) And C_ζ,2min(x_ζ,2min,y_ζ,2min) (ii) a The coordinate value of the centroid pixel is calculated as (x) through the formulas (5) and (6)_ζ,y_ζ)_ζ1 st decision vector in a parallelogram coding unit of

And 2 nd decision vector

And calculating the area division sine value 1sin alpha by the formulas (7) and (8)_ζSum region dividing sine value 2sin beta_ζ；

Case 1, if sin α_ζ＜0,sinβ_ζIf greater than 0, then C_ζ,1min(x_ζ,1min,y_ζ,1min) Is the centroid pixel coordinate value of (x)_ζ,y_ζ)_ζC for the 1 st coding region in the parallelogram coding unit_ζ,1min(x_ζ,1min,y_ζ,1min) Is assigned to C_ζ,1(x_ζ,1,y_ζ,1)；C_ζ,2min(x_ζ,2min,y_ζ,2min) Is the centroid pixel coordinate value of (x)_ζ,y_ζ)_ζC of the 6 th coding region in the parallelogram coding unit_ζ,2min(x_ζ,2min,y_ζ,2min) Is assigned to C_ζ,4(x_ζ,4,y_ζ,4)；

Case 2, if sin α_ζ＞0,sinβ_ζIf < 0, then C_ζ,2min(x_ζ,2min,y_ζ,2min) Is the centroid pixel coordinate value of (x)_ζ,y_ζ)_ζC for the 1 st coding region in the parallelogram coding unit_ζ,2min(x_ζ,2min,y_ζ,2min) Is assigned to C_ζ,1(x_ζ,1,y_ζ,1)；C_ζ,1min(x_ζ,1min,y_ζ,1min) Is the centroid pixel coordinate value of (x)_ζ,y_ζ)_ζC of the 6 th coding region in the parallelogram coding unit_ζ,1min(x_ζ,1min,y_ζ,1min) Is assigned to C_ζ,4(x_ζ,4,y_ζ,4)；

Step 14.9, no complicated background at the ζ thUnit binary image E of_ζBy having found the centroid pixel coordinate value of (x)_ζ,y_ζ)_ζThe calibration corner points C of the 1 st coding region and the 6 th coding region in the parallelogram coding unit_ζ,1(x_ζ,1,y_ζ,1) And C_ζ,4(x_ζ,4,y_ζ,4) C 'will be 4 pixel points'_ζ,1(x′_ζ,1,y′_ζ,1)、C′_ζ,2(x′_ζ,2,y′_ζ,2)、C′_ζ,3(x′_ζ,3,y′_ζ,3)、C′_ζ,4(x′_ζ,4,y′_ζ,4) The pixel coordinates of the rest 2 pixel points are respectively assigned to the centroid pixel coordinate value of (x)_ζ,y_ζ)_ζThe 1 st temporary coordinate value of the parallelogram coding unit of (1) is denoted as C'_ζ,5(x′_ζ,5,y′_ζ,5) And the 2 nd temporary coordinate value, denoted as C'_ζ,6(x′_ζ,6,y′_ζ,6) (ii) a The pixel coordinate value at the centroid can be found as (x) according to equations (9) and (10)_ζ,y_ζ)_ζOf the parallelogram coding unit of (3) th decision vector

And 4 th judgment vector

Step 14.10, judging the vector according to the No. 3

And 4 th judgment vector

The area division sine value 3sin omega can be obtained by the formula (11) and the formula (12)_ζSum region dividing sine value 4sin xi_ζ；

Case 1, sin ω_ζ＝＝0,sinξ_ζNot equal to 0, then C'_ζ,5(x′_ζ,5,y′_ζ,5) I.e. the centroid pixel coordinate value is (x)_ζ,y_ζ)_ζC 'to the index corner point of the 3 rd coding region in the parallelogram coding unit of (1)'_ζ,5(x′_ζ,5,y′_ζ,5) Is assigned to C_ζ,2(x_ζ,2,y_ζ,2)；C′_ζ,6(x′_ζ,6,y′_ζ,6) Is the centroid pixel coordinate value of (x)_ζ,y_ζ)_ζC 'to the index corner point of the 4 th coding region in the parallelogram coding unit of'_ζ,6(x′_ζ,6,y′_ζ,6) Is assigned to C_ζ,3(x_ζ,3,y_ζ,3)；

Case 2, sin ω_ζ≠0,sinξ_ζ0 to C'_ζ,6(x′_ζ,6,y′_ζ,6) I.e. the centroid pixel coordinate value is (x)_ζ,y_ζ)_ζC 'to the index corner point of the 3 rd coding region in the parallelogram coding unit of (1)'_ζ,6(x′_ζ,6,y′_ζ,6) Is assigned to C_ζ,2(x_ζ,2,y_ζ,2)；C′_ζ,5(x′_ζ,5,y′_ζ,5) Is the centroid pixel coordinate value of (x)_ζ,y_ζ)_ζC 'of the index corner point of the 4 th coding region in the parallelogram coding unit of (1)'_ζ,5(x′_ζ,5,y′_ζ,5) Coordinate values ofIs assigned to C_ζ,3(x_ζ,3,y_ζ,3)；

So far, the Zeth unit binary image E without complex background_ζIn the above, the centroid pixel coordinate value is found to be (x)_ζ,y_ζ)_ζIs marked with an angular point C of the 1 st coding region in the parallelogram coding unit_ζ,1(x_ζ,1,y_ζ,1) 3 rd coding region calibration corner point C_ζ,2(x_ζ,2,y_ζ,2) Calibration corner point C of the 4 th coding region_ζ,3(x_ζ,3,y_ζ,3) And the calibration corner point C of the 6 th coding region_ζ,4(x_ζ,4,y_ζ,4)；

Step 15, obtaining the coordinate value of the centroid pixel as (x)_ζ,y_ζ)_ζThe coded values of all the coded mark circles in the parallelogram coding unit are obtained, and a unit binary image E without a complex background with the Zeth unit is obtained_ζThe central pixel coordinate value is (x)_ζ,y_ζ)_ζThe coding number W of the parallelogram coding unit on the coding plane target placed in the actual space corresponding to the parallelogram coding unit_ζ(ii) a The method comprises the following specific steps:

step 15.1, according to the coordinate value of the centroid pixel as (x)_ζ,y_ζ)_ζIs marked with an angular point C of the 1 st coding region in the parallelogram coding unit_ζ,1(x_ζ,1,y_ζ,1) Calibration corner point C of the 6 th coding region_ζ,4(x_ζ,4,y_ζ,4) The centroid pixel coordinate value is (x) obtained from the formula (13)_ζ,y_ζ)_ζThe 5 th decision vector in the parallelogram coding unit of

Unit binary image E without complex background at zeta th_ζIn terms of centroid pixel coordinatesA value of (x)_ζ,y_ζ)_ζPositioning circle center of mass o 'of parallelogram encoding unit'_l,ζ(x′_l,ζ,y′_l,ζ) Make a 5 th decision vector as a starting point

Parallel and co-directional unit vectors, denoted as

And recording unit vector

The straight line is l_ζ,1(ii) a The coordinate value of the centroid pixel is (x)_ζ,y_ζ)_ζOf parallelogram-shaped coding units of (1)'_d,ζ(x′_d,ζ,y′_d,ζ) Make a 5 th decision vector as a starting point

Parallel and co-directional unit vectors, denoted as

And recording the straight line of the unit vector as l_ζ,2(ii) a Re-assigning the integer variable i to 1;

step 15.2, defining 6 floating point type two-dimensional arrays

For storing the value of the centroid pixel coordinate as (x)_ζ,y_ζ)_ζThe coding mark circular contour centroid of the parallelogram coding units in the No. 1 coding area, the No. 2 coding area, the No. 3 coding area, the No. 4 coding area, the No. 5 coding area and the No. 6 coding area is in the Zeth unit binary image without complex background_ζInitializing all elements in the 6 two-dimensional arrays according to the pixel coordinates, and assigning the values to be-1;taking 6 integer variables

And it is initialized by the computer system to be initialized,

step 15.3, binarizing the image E in the zeta th unit without complex background_ζCalculating the centroid pixel coordinate value as (x)_ζ,y_ζ)_ζIn a parallelogram coding unit of

Centroid pixel coordinates of

Respectively with the center o 'of the positioning circle'_l,ζAnd a directional ring center o'_d,ζThe formed ith group of 1 st quadrant vectors

And ith group of 2 nd quadrant vectors

According to the calculated 1 st quadrant vector of the ith group

And ith group of 2 nd quadrant vectors

Unit vector

And

and a direction vector

Calculated by the following equations (16), (17), (18) and (19)

cosγ_ζ、cosη_ζ、cosθ_ζ；

Judging the coordinate value of the centroid pixel as (x)_ζ,y_ζ)_ζIn the parallelogram-shaped coding unit of (1), the manner of coding the coding region to which the flag circle belongs is as follows:

case 1 if

Coded marker circle profile

The pixel falling on the centroid has a coordinate value of (x)_ζ,y_ζ)_ζOf the parallelogram coding unit1 in the coding region; order to

Then hold

Is assigned to

Reassign i +1 to i when i ≦ κ_ζThen execution of step 15.3 is resumed when i > k_ζThen the next step 15.4 is executed;

case 2 if

Coded marker circle profile

The pixel falling on the centroid has a coordinate value of (x)_ζ,y_ζ)_ζThe 2 nd coding region of the parallelogram coding unit of (1); order to

Then hold

Is assigned to

Reassign i +1 to i when i ≦ κ_ζThen execution of step 15.3 is resumed when i > k_ζThen the next step 15.4 is executed;

case 3 if

Coded marker circle profile

The pixel falling on the centroid has a coordinate value of (x)_ζ,y_ζ)_ζThe 3 rd coding region of the parallelogram coding unit of (1); order to

Then hold

Is assigned to

Reassign i +1 to i when i ≦ κ_ζThen execution of step 15.3 is resumed when i > k_ζThen the next step 15.4 is executed;

case 4, if

Coded marker circle profile

The pixel falling on the centroid has a coordinate value of (x)_ζ,y_ζ)_ζThe 4 th coding region of the parallelogram coding unit of (1); order to

Then hold

Is assigned to

Reassign i +1 to i when i ≦ κ_ζThen execution of step 15.3 is resumed when i > k_ζThen the next step 15.4 is executed;

situation 5, if

Coded marker circle profile

The pixel falling on the centroid has a coordinate value of (x)_ζ,y_ζ)_ζThe 5 th coding region of the parallelogram coding unit of (1); order to

Then hold

Is assigned to

Reassign i +1 to i when i ≦ κ_ζThen execution of step 15.3 is resumed when i > k_ζThen the next step 15.4 is executed;

case 6 if

Coded marker circle profile

The pixel falling on the centroid has a coordinate value of (x)_ζ,y_ζ)_ζThe 6 th coding region of the parallelogram coding unit of (1); order to

Then hold

Is assigned to

Reassign i +1 to i when i ≦ κ_ζThen execution of step 15.3 is resumed when i > k_ζThen the next step 15.4 is executed;

step 15.4, define

The value of the representative centroid pixel coordinate is (x)_ζ,y_ζ)_ζThe code value of the w-th bit of the flag circle (where w is 1,2) in the λ -th code region (where λ is 1,2,3,4,5,6) in the parallelogram coding unit of (1),

taking 0 or 1; taking an integer variable i, and endowing the i with an initial value i which is 1 again;

step 15.5, the step is divided into the following conditions:

case 1 if

Then

Assigning i +1 to i, and when i is more than 2, continuing to execute the next step 15.6; otherwise, returning to execute the step 15.5;

case 2 if

Recording coordinate points

To a straight line l_ζ,1A distance of

To a straight line l_ζ,3A distance of

If it is

And order

If it is

Then order

Assigning i +1 to i, and when i is more than 2, continuing to execute the next step 15.6; otherwise, returning to execute the step 15.5;

case 3 if

Recording coordinate points

To a straight line l_ζ,1A distance of

To a straight line l_ζ,3A distance of

If it is

Then order

If it is

Order to

Assigning i +1 to i, and when i is more than 2, continuing to execute the next step 15.6; otherwise, returning to execute the step 15.5;

case 4, if

Then order

Assigning i +1 to i, and when i is more than 2, continuing to execute the next step 15.6; otherwise, returning to execute the step 15.5;

step 15.6, the step is divided into the following conditions:

case 1 if

Then

Assigning i +1 to i, and when i is more than 4, continuing to execute the next step 15.6; otherwise, returning to execute the step 15.5;

case 2 if

Recording coordinate points

To a straight line l_ζ,2A distance of

To a straight line l_ζ,3A distance of

If it is

And order

If it is

Then order

Assign i +1 toGiving i, when i is more than 4, continuing to execute the next step 15.6; otherwise, returning to execute the step 15.5;

case 3 if

Recording coordinate points

To a straight line l_ζ,2A distance of

To a straight line l_ζ,3A distance of

If it is

Then order

If it is

Order to

Assigning i +1 to i, and when i is more than 4, continuing to execute the next step 15.6; otherwise, returning to execute the step 15.5;

case 4, if

Then order

Assigning i +1 to i, and when i is more than 4, continuing to execute the next step 15.6; otherwise, returning to execute the step 15.5;

step 15.7, the step is divided into the following conditions:

case 1 if

Then

Assigning i +1 to i, and when i is more than 6, continuing to execute the next step 15.8; otherwise, returning to execute the step 15.7;

case 2 if

Recording coordinate points

To a straight line l_ζ,1A distance of

To a straight line l_ζ,3A distance of

If it is

And order

If it is

Then order

Assigning i +1 to i, and when i is more than 6, continuing to execute the next step 15.8; otherwise, returning to execute the step 15.7;

case 3 if

Recording coordinate points

To a straight line l_ζ,1A distance of

To a straight line l_ζ,3A distance of

If it is

Then order

If it is

Order to

Assigning i +1 to i, and when i is more than 6, continuing to execute the next step 15.8; otherwise, returning to execute the step 15.7;

case 4, if

Then order

Assigning i +1 to i, and when i is more than 6, continuing to execute the next step 15.8; otherwise, returning to execute the step 15.7;

step 15.8, the centroid pixel coordinate value obtained by the above steps 15.5, 15.6 and 15.7 is (x)_ζ,y_ζ)_ζThe coded values of all the coded mark circles in the parallelogram coding unit can be obtained by the formula (20) and the unit binary image E without complex background_ζThe central pixel coordinate value is (x)_ζ,y_ζ)_ζThe coding number W of the parallelogram coding unit on the coding plane target placed in the actual space corresponding to the parallelogram coding unit_ζ；

W_ζ＝V_ζ ^T·U (20)

Wherein, the column vector U is (20, 2)¹,2²,...2¹¹)^TColumn vector

Step 16, obtaining the zeta unit binary image E without complex background_ζThe center of mass pixel coordinate is (x)_ζ,y_ζ)_ζ4 calibration angular points C on the parallelogram coding unit_ζ,1(x_ζ,1,y_ζ,1)、C_ζ,2(x_ζ,2,y_ζ,2)、C_ζ,3(x_ζ,3,y_ζ,3)、C_ζ,4(x_ζ,4,y_ζ,4) A non-unique code number of (a);

zeta-th unit binary image E without complex background_ζThe upper centroid pixel coordinate value is (x)_ζ,y_ζ)_ζThe non-unique coding number of the calibration corner point belonging to the sigma-th coding region (where sigma is 1,3,4,6) in the parallelogram coding unit of (1) is

Wherein the lower foot mark W_ζFor calibrating angular points

The coding number of the parallelogram coding unit, and the value of the upper corner mark sigma represents the calibration corner point

The sigma-th coding region; that is, the coordinates of the centroid pixel are obtained as (x)_ζ,y_ζ)_ζ4 calibration angular points C on the parallelogram coding unit_ζ,1(x_ζ,1,y_ζ,1)、C_ζ,2(x_ζ,2,y_ζ,2)、C_ζ,3(x_ζ,3,y_ζ,3)、C_ζ,4(x_ζ,4,y_ζ,4) Respectively has a non-unique code number of

(where σ_ζ,1＝1,σ_ζ,2＝3,σ_ζ,3＝4,σ_ζ,4＝6)；

Step 17, calculating to obtain the zeta unit binary image E without complex background_ζThe center of mass pixel coordinate is (x)_ζ,y_ζ)_ζ4 calibration angular points C on the parallelogram coding unit_ζ,1(x_ζ,1,y_ζ,1)、C_ζ,2(x_ζ,2,y_ζ,2)、C_ζ,3(x_ζ,3,y_ζ,3)、C_ζ,4(x_ζ,4,y_ζ,4) The specific steps of the unique code number are as follows:

obtaining the Zeth unit binary image E without complex background_ζThe upper centroid pixel coordinate value is (x)_ζ,y_ζ)_ζOn the basis of the non-unique code serial numbers of the 4 calibration angular points of the parallelogram coding unit, the unique code serial numbers of the 4 calibration angular points are calculated through the following specific steps:

step 17.1, take Delta'_ζ,1_σ′_ζ,1、Δ′_ζ,2_σ′_ζ,2、Δ′_ζ,3_σ′_ζ,3、Δ′_ζ,4_σ′_ζ,4Respectively used for storing the coordinate value of the centroid pixel as (x)_ζ,y_ζ)_ζ4 calibration angular points C on the parallelogram coding unit_ζ,1(x_ζ,1,y_ζ,1)、C_ζ,2(x_ζ,2,y_ζ,2)、C_ζ,3(x_ζ,3,y_ζ,3)、C_ζ,4(x_ζ,4,y_ζ,4) Is unique code number of, wherein'_ζ,1、Δ′_ζ,2、Δ′_ζ,3、Δ′_ζ,4、σ′_ζ,1、σ′_ζ,2、σ′_ζ,3、σ′_ζ,4Are all positive integers;

step 17.2, taking an integer variable i and re-assigning the value of i to 1;

step 17.3, judging whether N is an even number, if N is an odd number, executing step 17.4; if N is an even number, taking an integer parameter delta and assigning the value delta to be N/2, and calibrating the corner point C_ζ,i(x_ζ,i,y_ζ,i) Non-unique code number of

This step can be divided into the following cases:

case 1, if σ_ζ,i1 or σ_ζ,iWhen W is equal to 6, the product is put in_ζValue of to delta'_ζ,iWill σ_ζ,iValue of to σ'_ζ,iThen calibrating the corner point C_ζ,i(x_ζ,i,y_ζ,i) Is delta 'as the unique code number'_ζ,i_σ′_ζ,i；

Case 2, if σ_ζ,i(W) 3 ═ 3_ζValue of- Δ) to Δ'_ζ,iAssigning 6 to σ'_ζ,iThen calibrating the corner point C_ζ,i(x_ζ,i,y_ζ,i) Is delta 'as the unique code number'_ζ,i_6；

Case 3, if σ_ζ,i(W) is 4 ═ 4_ζValue of-Delta-1) to Delta'_ζ,iAssigning 1 to σ'_ζ,iThen calibrating the corner point C_ζ,i(x_ζ,i,y_ζ,i) Is delta 'as the unique code number'_ζ,i_1；

Judging whether i is smaller than 4, if i is smaller than 4, assigning i +1 to i, and returning to the step 17.3 for sequential execution; otherwise, executing step 18;

step 17.4, taking the integer parameter delta, assigning the value delta to be (N +1)/2, and calibrating the corner point C_ζ,i(x_ζ,i,y_ζ,i) Non-unique code number of

This step can be divided into the following cases:

case 1, if σ_ζ,i1 or σ_ζ,iWhen W is equal to 6, the product is put in_ζValue of to delta'_ζ,iWill σ_ζ,iValue of to σ'_ζ,iThen calibrating the corner point C_ζ,i(x_ζ,i,y_ζ,i) Is delta 'as the unique code number'_ζ,i_σ′_ζ,i；

Case 2, if σ_ζ,iWhen the value is 3, the following two cases are divided into:

(1) when phi is_pWhen being equal to 1, will(W_ζValue of- Δ ') to Δ'_ζ,iAssigning 6 to σ'_ζ,iThen calibrating the corner point C_ζ,i(x_ζ,i,y_ζ,i) Is delta 'as the unique code number'_ζ,i_σ′_ζ,i(ii) a Delta' can be derived from the formula (21),

wherein Δ ″ ═ 2 (W)_ζ-z_v) V (N +1) +1 (integers only retained);

(2) when phi is_pWhen being equal to 2, (W) is_ζValue of- Δ '") to Δ'_ζ,iAssigning 6 to σ'_ζ,iThen calibrating the corner point C_ζ,i(x_ζ,i,y_ζ,i) Is delta 'as the unique code number'_ζ,i_σ′_ζ,i(ii) a Δ' "can be obtained from equation (22),

wherein Δ ″ ═ 2 (W)_ζ-z_v+1)/(N +1) +1 (integers only retained);

case 3, if σ_ζ,iThe following two cases are divided into two cases:

(1) when phi is_pWhen the value is 1, (W) is_ζValue of- Δ ') to Δ'_ζ,iAssigning 1 to σ'_ζ,iThen calibrating the corner point C_ζ,i(x_ζ,i,y_ζ,i) Is delta 'as the unique code number'_ζ,i_σ′_ζ,iWherein Δ' can be derived from formula (23);

wherein Δ ″ ═ 2 (W)_ζ-z_v) V (N +1) +1 (integers only retained);

(2) when phi is_pWhen being equal to 2, (W) is_ζ- Δ' ") is assigned to Δ′_ζ,iAssigning 1 to σ'_ζ,iThen calibrating the corner point C_ζ,i(x_ζ,i,y_ζ,i) Is delta 'as the unique code number'_ζ,i_σ′_ζ,iΔ' "can be derived from equation (24),

wherein Δ ″ ═ 2 (W)_ζ-z_v+1)/(N +1) +1 (integers only retained);

judging whether i is smaller than 4, if i is smaller than 4, assigning i +1 to i, and returning to the step 17.4 to execute in sequence; otherwise, executing step 18;

thus, the zeta unit binary image E without complex background is obtained_ζThe upper centroid pixel coordinate value is (x)_ζ,y_ζ)_ζThe one-to-one correspondence relationship between the pixel coordinates of the 4 calibration corner points of the parallelogram coding unit and the unique coding serial number thereof is as follows:

calibrating angular point C_ζ,1(x_ζ,1,y_ζ,1) Corresponding unique code number is delta'_ζ,1_σ′_ζ,1；

Calibrating angular point C_ζ,2(x_ζ,2,y_ζ,2) Corresponding unique code number is delta'_ζ,2_σ′_ζ,2；

Calibrating angular point C_ζ,3(x_ζ,3,y_ζ,3) Corresponding unique code number is delta'_ζ,3_σ′_ζ,3；

Calibrating angular point C_ζ,4(x_ζ,4,y_ζ,4) Corresponding unique code number is delta'_ζ,4_σ′_ζ,4；

Step 18, establishing a target coordinate system O_t-X_tY_tZ_t(ii) a The specific process is as follows:

step 18.1, recording the number of calibration corner points in 4 vertexes of the 1 st parallelogram coding unit in the 1 st line as phi_pThen can be according to phi_pThe numerical values are classified into the following two cases:

case 1 when phi_pWhen 1, the 1 st parallelogram coding unit in the 1 st line is denoted

In as the origin calibration corner point alpha'₁At the moment, an origin is selected to mark the angular point alpha'₁Origin O as target coordinate system_tTo assist the vector

As a target coordinate system X_tThe direction of the axis;

case 2 when phi_pWhen 2, the 1 st parallelogram coding unit in the 1 st row is respectively marked

Is epsilon 'as two calibration corner points'₃And ε₃According to the calibrated corner point epsilon'₃And ε₃The positional relationship of (c) can be further classified into the following cases:

(1) when vector

Direction and auxiliary vector of

Is the same, the calibration corner point epsilon 'is selected at the moment'₃Origin O as target coordinate system_tTo assist the vector

Is taken as X of a target coordinate system_tThe direction of the axis;

(2) when vector

Direction and auxiliary vector of

When the directions of the two points are different, the calibration corner point epsilon' is selected at the moment₃Origin O as target coordinate system_tTo assist the vector

Is taken as X of a target coordinate system_tThe direction of the axis;

step 18.2, with forward vector

As Z of the target coordinate system_tDirection of axis, X of target coordinate system_tAxis, Z_tAxis and Y_tThe axis meets the right-hand criterion, so as to establish a target coordinate system O_t-X_tY_tZ_t；

Step 19, obtaining the zeta unit binary image E without complex background by using the target coordinate calculation method of the calibration corner point on the coding plane target_ζThe center of mass pixel coordinate is (x)_ζ,y_ζ)_ζThe specific steps of the target coordinate values of the 4 calibration corner points on the parallelogram coding unit are as follows:

step 19.1, taking an integer variable i and re-assigning the value of i to 1;

step 19.2, judging whether N is an even number, if N is an odd number, executing step 19.3; if N is an even number, the step is divided into the following cases:

case 1, if Δ'_ζ,i_σ′_ζ,iOf σ'_ζ,i1 ═ 1; then the unique code number is delta'_ζ,i_σ′_ζ,iThe target coordinates corresponding to the calibration corner points are as follows:

wherein when

When taken, when

Taking-;

case 2, if Δ'_ζ,i_σ′_ζ,iOf σ'_ζ,i6; then the unique code number is delta'_ζ,i_σ′_ζ,iThe target coordinates corresponding to the calibration corner points are as follows:

wherein when

When taken, when

Taking-;

in this step 19.2, the process is now described,

when in use

In the case of an odd number of the groups,

when in use

In the case of an even number, the number of the first,

after the execution of the step is finished, directly executing a step 19.4;

step 19.3, the step is divided into the following two cases:

case 1, if Δ'_ζ,i_σ′_ζ,iOf σ'_ζ,i1 ═ 1; then the unique code number is delta'_ζ,i_σ′_ζ,iThe target coordinates corresponding to the calibration corner points are as follows:

wherein when

When taken, when

Taking-;

case 2, if Δ'_ζ,i_σ′_ζ,iOf σ'_ζ,i6; then the unique code number is delta'_ζ,i_σ′_ζ,iThe target coordinates corresponding to the calibration corner points are as follows:

wherein when

When taken, when

Taking-;

in this step 19.3

(the result retains only integer bits);

when in use

In the case of an odd number of the groups,

when in use

In the case of an even number, the number of the first,

step 19.4, judging whether i is smaller than 4, if i is smaller than 4, assigning i +1 to i and returning to the step 19.2 to execute in sequence; if i is more than or equal to 4, finishing the coordinates of the centroid pixel as (x)_ζ,y_ζ)_ζCalculating the target coordinate values of 4 calibration angular points on the parallelogram coding unit, and obtaining the matching relation of the sub-pixel coordinates, the unique coding number and the target coordinates of the 4 calibration angular points:

unique code number of delta'_ζ,1_σ′_ζ,1Pixel coordinate C of the calibration corner point_ζ,1(x_ζ,1,y_ζ,1) The corresponding target coordinate is (X)_ζ,1,Y_ζ,1,0)；

Unique code number of delta'_ζ,2_σ′_ζ,2Pixel coordinate C of the calibration corner point_ζ,2(x_ζ,2,y_ζ,2) The corresponding target coordinate is (X)_ζ,2,Y_ζ,2,0)；

Unique code number of delta'_ζ,3_σ′_ζ,3Pixel coordinate C of the calibration corner point_ζ,3(x_ζ,3,y_ζ,3) The corresponding target coordinate is (X)_ζ,3,Y_ζ,3,0)；

Unique code number of delta'_ζ,4_σ′_ζ,4Pixel coordinate C of the calibration corner point_ζ,4(x_ζ,4,y_ζ,4) The corresponding target coordinate is (X)_ζ,4,Y_ζ,4,0)；

And 20, endowing zeta +1 with zeta, and circularly executing the steps 13 to 19 to obtain target coordinate values of all calibration corner points on the mu parallelogram coding units.

Therefore, according to all the steps, the gray image P of the plane target can be obtained and coded₁Target coordinates corresponding to the pixel coordinates of all calibration corner points in the polygon L with the maximum number of the middle calibration corner points are found, namely the one-to-one correspondence relationship between the pixel coordinates of the selected calibration corner point and the target coordinates is found, and simultaneously the unique coding serial number of the selected calibration corner point is also found, thereby completing the coding of the planar targetAnd (4) decoding.

The invention also provides a computer-readable storage medium comprising a computer program for use in conjunction with an electronic device having image processing capabilities, said computer program being executable by a processor to perform said decoding method.

Compared with the prior art, the invention has the following beneficial effects:

1. according to the invention, the positioning patterns and the orientation patterns are arranged in the grids of each parallelogram coding unit, so that the rotation direction of the target can be automatically judged by a computer in the camera calibration process, and the flexibility of camera calibration is improved;

2. according to the invention, a plurality of coding mark patterns are arranged in each parallelogram coding unit, each parallelogram coding unit can be numbered and subjected to region division, and each characteristic angular point is given a determined and unique code, so that high-precision matching of the same-name calibration angular points in different calibration images can be realized even if an incomplete coding plane target is shot in the calibration process of a multi-camera;

3. the decoding method of the coding plane target has high decoding speed, completes decoding by utilizing the connected domain, the vector relation, the position relation and the like, has high efficiency, can realize real-time decoding, and provides a basis for real-time calibration;

4. the decoding method of the coding plane target can effectively remove the interference of noise, can finish calibration under a complex background, has strong robustness, and the target is often in the complex background in the actual calibration process, so the coding plane target and the decoding mode thereof have high practical value;

5. in the coding plane target and the decoding method thereof adopted by the invention, the calibration corner points can be extracted to be in a sub-pixel level, the extraction precision of the calibration corner points is high, and the calibration with higher precision can be realized.

Drawings

FIG. 1 is a schematic representation of an encoding planar target in an embodiment of the present invention;

FIG. 2 is a block diagram of an embodiment of the present inventionPrescribed vector of face target

And an auxiliary vector

A schematic diagram of (a);

FIG. 3 is a schematic diagram of a polygon L with a maximum number of calibration corners of 4 rows × 8 columns extracted by a growth-based tessellated corner extraction algorithm;

FIG. 4 is a target grayscale image P obtained by performing 8-bit grayscale processing on a captured coded planar target image₁A schematic diagram of (a);

FIG. 5 is a target gray scale image P of the ablation target₁Complex background-free target gray level image P obtained by calibrating complex background outside polygon L with maximum angular point number₁' schematic view;

FIG. 6 is a gray scale image P of a target without a complex background₁' binarization image P without complex background target obtained by binarization processing₂A schematic diagram of (a);

FIG. 7 is a unit binary image E without complex background₁A schematic diagram of (a);

fig. 8 is a flowchart illustrating the method for decoding the encoding plane target according to the present invention.

Detailed Description

The following detailed description of the preferred embodiments of the present invention, taken in conjunction with the accompanying drawings, will make the advantages and features of the invention easier to understand by those skilled in the art, and thus will clearly and clearly define the scope of the invention.

Referring to fig. 1, a coding plane target for camera calibration is composed of a coding checkerboard formed by alternating parallelogram coding units and parallelogram non-coding units, the coding plane target uses the intersection points of the parallelogram coding units connected by any opposite angles as the calibration angular points of the coding plane target, and the coding plane target shown in fig. 1 totally contains 4 rows × 12 columns of calibration angular points; the interior of each parallelogram coding unit in the coding plane target is provided with a coding pattern, the coding pattern comprises a positioning pattern, an orientation pattern and a coding mark pattern, and the coding mark pattern consists of 12 coding unit patterns; the judgment of the rotation direction of the coding plane target can be realized by the orientation pattern and the positioning pattern; the coding mark pattern is used for coding each calibration corner point in the coding plane target.

In this embodiment, the vector determines the first vertex o ″' of the coding unit₁The vector determines a first point o' on a first side of the coding unit₂Specifying the vector

And an auxiliary vector

As shown in fig. 2.

In this embodiment, the parallelogram-shaped coding unit is a square with a side length of 24 mm, and λ is 90 °.

As shown in fig. 1 and 2, the positioning pattern in each parallelogram-shaped coding unit within the coding plane target is a solid circle with a diameter of 6 mm, the orientation patterns are circular rings with an outer diameter of 6 mm and an inner diameter of 3 mm, and the positional relationship of the positioning pattern and the orientation patterns satisfies the following condition: the positioning pattern and the orientation pattern of the same parallelogram coding unit are both arranged inside the parallelogram coding unit, the mass center of the positioning pattern and the mass center of the orientation pattern in the same parallelogram coding unit are both arranged near the mass center of the parallelogram coding unit, and the direction and the specified vector pointing to the mass center of the positioning pattern from the mass center of the orientation pattern in the same parallelogram coding unit

Are in the same direction;

the sizes of a plurality of coding unit patterns in the same parallelogram coding unit in the coding plane target can be different from each other or can be different from each other; in the embodiment of the present invention, as shown in fig. 1, the 12 coding unit patterns in the same parallelogram coding unit in the coding plane target are all solid circles with a diameter of 3 mm;

each parallelogram coding unit and the positioning pattern and the coding unit pattern inside the parallelogram coding unit in the coding plane target satisfy the following relations: in the same parallelogram coding unit, the contour length of each coding unit pattern is smaller than that of the positioning pattern, and the contour length of the positioning pattern is smaller than the perimeter (2a +2b) of the parallelogram coding unit; in this embodiment (as shown in fig. 1), in the same parallelogram coding unit, the contour length of each coding unit pattern is 9.42 mm smaller than the contour length of the positioning pattern is 18.85 mm, and the contour length of the positioning pattern is 18.85 mm smaller than the perimeter of the parallelogram coding unit, which is 96 mm.

The background colors of all the parallelogram coding units in the coding plane target are the same, and the background colors of all the parallelogram coding units in the coding plane target are marked as color 1; the colors of all the parallelogram non-coding units in the coding plane target are the same, and the colors of all the parallelogram non-coding units in the coding plane target are marked as color 2; the background color (i.e. color 1) of all parallelogram coding units in the coding plane target is obviously different from the color (i.e. color 2) of all parallelogram non-coding units; in a specific embodiment (as shown in fig. 1), the background color of all parallelogram-encoded units in the encoded planar target is black (i.e., color 1), and is significantly different from the color of all parallelogram-non-encoded units in the encoded planar target being white (i.e., color 2);

the colors of all the positioning patterns and all the orientation patterns contained in all the parallelogram coding units in the coding plane target are the same, the colors of all the positioning patterns and all the orientation patterns contained in all the parallelogram coding units in the coding plane target are marked as color 3, and the color 3 is obviously different from the color 1; in the embodiment of the present invention, the colors of all the positioning patterns and the orientation patterns contained in all the parallelogram coding units in the coding plane target are white (i.e. color 3); in this embodiment (as shown in fig. 1), the color 3 and the color 2 are both white, and the color 3 (white) is obviously different from the color 1 (black);

the color of all coding unit patterns contained in all parallelogram coding units in the coding plane target is the same as color 1 or the same as color 3; in an embodiment (as shown in fig. 1), the color of all the coding unit patterns in the coding plane target is black (color 1) or white (color 3);

as shown in fig. 1, the connected component of black color (i.e. color 1) in each parallelogram coding unit in the coding plane target has the following features: the same parallelogram coding unit contains 2 black (namely color 1) connected domains, and the area of the black (namely color 1) connected domain closest to the centroid of the oriented pattern is smaller than that of the other black (namely color 1) connected domain;

the areas of the positioning patterns contained in different parallelogram coding units in the coding plane target can be the same or different; as shown in fig. 1, the areas of the positioning patterns included in different parallelogram coding units in the coding plane target in this embodiment are the same;

the area sizes of the orientation patterns contained in different parallelogram coding units in the coding plane target can be the same or different; as shown in fig. 1, the areas of the orientation patterns contained in different parallelogram coding units in the coding plane target in this embodiment are the same;

the areas of the coding unit patterns contained in different parallelogram coding units in the coding plane target can be the same or different; as shown in fig. 1, the coding unit patterns included in different parallelogram coding units in the coding plane target in the present embodiment have the same area size;

in the present embodiment, the coding unit pattern of each parallelogram coding unit in the coding plane target has the following characteristics: as shown in fig. 1, in the same parallelogram coding unit, the position and color of the coding unit pattern are determined by the non-unique coding method of each calibration corner point in the coding plane target;

in the coding plane target, the coding number of the parallelogram coding unit with the coding serial number W (wherein W is more than or equal to 0 and less than or equal to 32) is determined by the positions and the colors of all the coding unit patterns inside the parallelogram coding unit with the coding serial number W, and the coding plane target decoding method can analyze the coding number of each parallelogram coding unit and the coding number of the calibration corner point in the image according to the position and the color information of all the coding unit patterns inside each parallelogram coding unit on the coding plane target in the image.

The steps of decoding each calibration corner point in the coding plane target by using a digital image processing method are as follows:

step 1, inputting basic information of a coding plane target placed in a space, namely the coding plane target positioned in the space comprises 8 rows multiplied by 12 columns of calibration angular points, the code number of an initial parallelogram coding unit of the coding plane target is 0, and the number phi of the calibration angular points in 4 vertexes of a 1 st parallelogram coding unit of a 1 st row on the coding plane target_p＝＝1；

Shooting the coding plane target in the space through a camera, thereby obtaining an image of the coding plane target, wherein the coding plane target image comprises the complete or local coding plane target;

step 2, carrying out 8-bit gray level processing on the coded plane target image, and recording an image obtained by carrying out gray level processing on the coded plane target image as a coded plane target gray level image P₁(ii) a Wherein, the planar target gray image P is coded₁An 8-bit gray scale map, as shown in FIG. 4;

step 3, establishing a pixel coordinate system of the calibration corner point:

in the shot coding plane target image, taking the upper left corner of the image as the origin o of a pixel coordinate system of the calibration corner point, wherein the x-axis direction of the pixel coordinate system of the calibration corner point is from left to right, and the y-axis direction of the pixel coordinate system of the calibration corner point is from top to bottom; thereby establishing a pixel coordinate system o-xy of the calibration corner point;

using a growth-based checkerboard corner extraction algorithm (checkerboard detection algorithm proposed by Automatic Camera and Range Sensor Calibration using a single Shot)Method) extracting a coded planar target grayscale image P₁The polygon surrounded by the outermost corner points (i.e. the calibration corner point of row 1, the calibration corner point of column 1, the calibration corner point of row 4 and the calibration corner point of column 8) in the sub-pixel coordinate set of calibration corner points of row 4 × 8 is marked as the polygon with the maximum number of calibration corner points L, as shown in fig. 3; wherein, the coded plane target gray image P after the angular point extraction₁No change occurred;

step 4, in the said coded plane target gray image P₁In the method, the gray values of all the pixels inside the polygon L with the maximum number of the calibration angle points in the step 3 are kept unchanged by using a digital image processing method, the gray values of all the pixels outside the polygon L are assigned to be 255, and the gray image P of the coding plane target is processed₁The image obtained by the processing is recorded as a gray image P without a complex background target₁', as shown in FIG. 5;

step 5, aiming at the gray image P of the target without the complex background₁' binarization processing is carried out, and a target gray level image P without complex background is obtained₁' the image obtained by binarization processing is marked as a binarized image P without a complex background target₂So that the image P is binarized on the target without complex background₂The background color of the middle parallelogram coding unit is changed into black, the colors of the background color of the parallelogram non-coding unit, the positioning pattern and the orientation pattern are all changed into white, and the color of the coding mark pattern can be white or black according to the coding rule, as shown in fig. 6;

6, according to the gray image P of the coded plane target₁The extracted maximum calibration corner number polygon L contains 4 rows × 8 columns of calibration corners. In this embodiment, m and n are even numbers, and the estimated number μ' of the parallelogram coding units included in the polygon L can be calculated by the formula (2): μ ═ [ (m-1) (n-1) +1]If/2 is 11, the number μ of parallelogram coding units actually contained in the polygon L is less than or equal to 11;

setting parallelogram coding sheetThe element number judgment threshold value L' is 0.2; target binary image P without complex background₂Performing black connected domain corrosion treatment on the image to ensure that no complex background target binaryzation image P₂All the parallelogram coding units are disconnected at the diagonal positions, and the complex background-free target binary image P is obtained₂The image obtained by the processing is marked as a target binaryzation corrosion image P'₂；

Binarizing corrosion image P 'at target'₂Searching 11 maximum black connected domains, and calculating an average value χ 'of pixel points included in the first 10 maximum black connected domains, which may be calculated to obtain χ' 168 in this embodiment;

marking the minimum black connected domain of the 11 maximum black connected domains in the polygon L as the tail end black connected domain, and calculating the pixel point chi contained in the tail end black connected domain_mChi in the present embodiment_m164, get L ═ 0.024 according to equation (3), satisfy L ″ < L', copy 11 to μ, μ ═ 11, and perform step 8;

step 8, finding binaryzation corrosion image P 'in target'₂11 maximum black connected domains in the image are respectively marked as grid connected domains omega₁Grid connected domain omega₂…, grid connected domain omega₁₁(ii) a Taking an integer variable i, and giving an initial value i to 1;

binarizing corrosion image P 'at target'₂Calculating the square connected domain omega in the above steps_iPixel coordinate of centroid (x)_i,y_i)_iAnd (5) reassigning i +1 to i, and continuing to execute the step until i is greater than 11, thereby obtaining a target binary corrosion image P'₂Upper square connected domain omega₁Grid connected domain omega₂…, grid connected domain omega₁₁Centroid pixel coordinates (1154,696)₁、…、(x₁₁,y₁₁)₁₁And will (1154,696)₁、…、(x₁₁,y₁₁)₁₁Sequentially serving as a 1 st element, a 2 nd element, … and an 11 th element in a parallelogram coding unit centroid pixel coordinate set A;

step 9, assigning an initial value i to the integer variable i again, wherein the initial value i is 1;

binarizing corrosion image P 'at target'₂In (1), calculating the distance grid connected domain omega_iCentroid pixel coordinate (x)_i,y_i)_iThe nearest black connected domain is recorded as a target binary corrosion image P'₂Of (1) ring center connected region omega'_i(ii) a The step is continuously executed after i +1 is reassigned to i until i is greater than 11; finally obtaining target binaryzation corrosion images P'₂Of (1) ring center connected region omega'₁And omega 'of circular ring center connected region'₂…, ring center connected region omega'₁₁；

Step 10, assigning an initial value i to the integer variable i again, wherein the initial value i is 1;

binarizing corrosion image P 'at target'₂In (1), calculating the target binaryzation corrosion image P'₂Of (1) ring center connected region omega'_iCentroid pixel coordinate o ″)_d,i(x″_d,i,y″_d,i) Assigning i +1 to i again, and continuing to execute the step until i is greater than 11; thus obtaining target binaryzation corrosion images P'₂Of (1) ring center connected region omega'₁And omega 'of circular ring center connected region'₂…, ring center connected region omega'₁₁Centroid pixel coordinate o ″)_d,1(1211,715)、…、o″_d,11(x″_d,11,y″_d,11) Sequentially as the 1 st element, the 2 nd element, … and the 11 th element in the circular ring centroid pixel coordinate set B;

step 11, binarizing the corrosion image P 'on the target'₂In, will remove square connected domain omega₁Grid connected domain omega₂…, grid connected domain omega₁₁And a circular ring center connected region omega'₁And omega 'of circular ring center connected region'₂…, ring center connected region omega'₁₁The gray values of the other black connected domains are all assigned to be 255, and the target is subjected to binarization to form a corrosion image P'₂The image obtained by the processing is recorded as a decoded binary image P₃；

Step 12, taking an integer variable zeta, and giving an initial value zeta as 1;

step 13, in the step, obtaining the 1 st unit binary image E without complex background₁The method comprises the following specific steps:

step 13.1, decoding the binary image P₃Copying and backing up, and recording the copied image as a 1 st backup binary image P_1,4；

Step 13.2, backup binarization image P at 1 st_1,4Taking the 1 st centroid coordinate value in the parallelogram coding unit centroid pixel coordinate set A (1154,696)₁Finding the coordinate value of distance centroid in the set of calibration corner points Q (1154,696)₁Pixel coordinate values of the nearest 4 calibration corner points, and the binarization image P at the 1 st backup_1,4Respectively marking 4 pixel points corresponding to the pixel coordinate values of the 4 calibration angular points as C₁″_,1(1333,546.2)、C₁″_,2(1333,790.8)、C₁″_,3(1088,790.8)、C₁″_,4(1087,546.2); and taking the 4 pixel points as the 1 st calibration angular point quadrangle S₁And connecting the 4 vertexes to form a 1 st calibration corner point quadrangle S₁；

Step 13.3, finding out the 1 st barycenter pixel coordinate value in the barycenter pixel coordinate set A of the parallelogram coding unit in the ring barycenter pixel coordinate B in step 10 (1154,696)₁A corresponding circle centroid pixel coordinate of circle 1 (1211,715);

step 13.4, backup binarization image P at 1 st_1,4Searching a white connected domain closest to the coordinate value (1211,715) of the centroid of the circular ring, and assigning the gray value of the white connected domain as 0;

step 13.5, backup binarization image P at 1 st_1,4In the above, the 1 st calibration corner point quadrangle S₁Except that the gray values of all the pixel points are assigned to be 255, and the 1 st calibration corner point quadrangle S₁Keeping the gray values of all internal pixel points unchanged, and marking the obtained image as the 1 st unit binary image E without complex background₁As in FIG. 7;

step 14, binarizing the image E in the zeta th unit without complex background_ζIn the method, a calibration angular point of a 1 st parallelogram coding unit is found and obtained, and a coding region to which the corresponding calibration angular point belongs is determined, and the method specifically comprises the following steps:

step 14.1, binarizing the image E in the 1 st unit without complex background₁In the method, a unit binary image E with the maximum black connected domain and marked as the 1 st no complex background is searched₁Maximum black connected component Ω in_1,E(ii) a Extracting the 1 st unit binary image E without complex background₁Maximum black connected component Ω in_1,EAnd is recorded as the centroid pixel coordinate value of (1154,696)₁Of a parallelogram-shaped coding unit D₁；

Step 14.2, the coordinate value of the centroid pixel is (1154,696)₁Of a parallelogram-shaped coding unit D₁In the method, the number of pixel points contained in each contour is counted, wherein the contour containing the second most pixel points is the 1 st unit binary image E without complex background₁The pixel coordinate value of the middle mass center is (1154,696)₁In a parallelogram coding unit of (2) an outline G of a positioning circle₁Calculating the positioning circle profile G₁And is recorded as the 1 st unit binary image without complex background₁The coordinate value of the upper centroid pixel is (1154,696)₁Positioning circular centroid pixel coordinate o 'in parallelogram coding unit of (1)'_l,1(1211,621)；

Step 14.3, the coordinate value of the centroid pixel in the above step is (1154,696)₁Of a parallelogram-shaped coding unit D₁In (1), the 2 contours with the largest number of pixels are removed, and the remaining k₁(wherein κ₁0,1,2, 3.) contours, in this example κ₁If 2, the 2 contours are the 1 st unit binarized image E without complex background₁The coordinate of the upper mass center is (1154,696)₁The coding mark circle contour in the parallelogram coding unit is respectively marked as the coding mark circle contour

Coded marker circle profile

Step 14.4, assigning the initial value i to the integer variable i again, wherein the initial value i is 1;

step 14.5, binarizing the image E in the 1 st unit without complex background₁Calculating the contour of the coding mark circle

Centroid pixel coordinates of

Assigning i +1 to i again and continuing to execute the step until i is greater than 2; can obtain the corresponding coding mark circular contour

Coded marker circle profile

Centroid pixel coordinates of

Step 14.6, binarizing the image E in the 1 st unit without complex background₁And recording the pixel point with the pixel coordinate value of (1211,715) as the centroid coordinate value of (1154,696)₁Of parallelogram-shaped coding units of (2) oriented circular ring centroid o'_d,1(1211,715); and binarizing the image E in the 1 st cell without complex background₁In the above, 4 pixels having pixel coordinate values of (1333,546.2), (1333,790.8), (1088,790.8) and (1087,546.2) are denoted as C'_1,1(1333,546.2)、C′_1,2(1333,790.8)、C′_1,3(1088,790.8)、C′_1,4(1087,546.2)；

Step 14.7, binarizing the image E in the 1 st unit without complex background₁Upper, get C_1,1(x_1,1,y_1,1)、C_1,2(x_1,2,y_1,2)、C_1,3(x_1,3,y_1,3)、C_1,4(x_1,4,y_1,4) Respectively representing a centroid pixel coordinate value of (1154,696)₁The pixel coordinates of the calibration corner points of the No. 1 coding region, the No. 3 coding region, the No. 4 coding region and the No. 6 coding region in the parallelogram coding unit; the centroid pixel coordinate value is (1154,696)₁In a parallelogram coding unit

This can be derived from equation (4):

simultaneously recording through the center of mass o 'of the positioning circle'_l,1And a directional ring centroid o'_d,1Is a straight line of_1,3；

Step 14.8, binarizing the image E in the 1 st unit without complex background₁Last, 4 pixel points C'_1,1(1333,546.2)、C′_1,2(1333,790.8)、C′_1,3(1088,790.8)、C′_1,4(1087,546.2) distance-located circular centroid pixel coordinate o'_l,1(1211,621) the nearest 2 pixels are respectively marked as C_1,1min(x_1,1min,y_1,1min) And C_1,2min(x_1,2min,y_1,2min) (ii) a In this embodiment, C_1,1min(x_1,1min,y_1,1min) Is C'_1,1(1333,546.2)，C_1,2min(x_1,2min,y_1,2min) Is C'_1,4(1087,546.2) calculating the centroid pixel coordinate value (1154,696) by the formulas (5) and (6)₁1 st decision vector in a parallelogram coding unit of

And 2 nd decision vector

Respectively as follows:

the area division sine value 1sin alpha is calculated by the formula (7) and the formula (8)₁Sum region dividing sine value 2sin beta₁Respectively as follows:

due to sin alpha₁＜0,sinβ₁If greater than 0, then C_1,1min(1333,546.2) the centroid pixel coordinate value is (1154,696)₁C for the 1 st coding region in the parallelogram coding unit_1,1min(1333,546.2) assigning a pixel coordinate value to C_1,1(x_1,1,y_1,1)；C_1,2min(1088,546.2) the centroid pixel coordinate value is (1154,696)₁C of the 6 th coding region in the parallelogram coding unit_1,2min(1088,546.2) assigning a pixel coordinate value to C_1,4(x_1,4,y_1,4)；

Step 14.9, binarizing the image E in the 1 st unit without complex background₁The coordinate value of the centroid pixel is found to be (1154,696)₁The calibration corner points C of the 1 st coding region and the 6 th coding region in the parallelogram coding unit_1,1(1333,546.2) and C_1,4(1088,546.2); c 'of 4 pixel points'_1,1(1333,546.2)、C′_1,2(1333,790.8)、C′_1,3(1088,790.8)、C′_1,4(1087,546.2) the remaining 2 pixels (in this example, C'_1,2(1333,790.8) and C'_1,3(1088,790.8)) are assigned to centroid pixel coordinate values of (1154,696)₁The 1 st temporary coordinate value of the parallelogram coding unit of (2) is denoted as C'_1,5(1333,790.8), and the 2 nd temporary coordinate value is marked as C'_1,6(1088,790.8); the coordinates of the centroid pixel are obtained from the equations (9) and (10) as (1154,696)₁Of the parallelogram coding unit of (3) th decision vector

And 4 th judgment vector

Respectively as follows:

step 14.10, according to the calculated 3 rd judgment vector

And 4 th judgment vector

The area division sine value 3sin omega can be obtained by the formula (11) and the formula (12)₁Sum region dividing sine value 4sin xi₁Respectively as follows:

due to sin omega₁＝＝0,sinξ₁Not equal to 0, then C'_1,5(1333,790.8) the centroid pixel coordinate value is (1154,696)₁C 'to the index corner point of the 3 rd coding region in the parallelogram coding unit of (1)'_1,5(1333,790.8) to C_1,2(x_1,2,y_1,2)；C′_1,6(1088,790.8) the centroid pixel coordinate value is (1154,696)₁C 'to the index corner point of the 4 th coding region in the parallelogram coding unit of'_1,6(1088,790.8) to C_1,3(x_1,3,y_1,3)；

So far, the image E is binarized in the 1 st unit without complex background₁In the above, the centroid pixel coordinate value is found to be (1154,696)₁Is marked with an angular point C of the 1 st coding region in the parallelogram coding unit_1,1(1333,546.2) and a 3 rd coding region calibration corner point C_1,2(1333,790.8) and a calibration corner point C of the 4 th encoding region_1,3(1088,790.8) and the calibration corner point C of the 6 th encoding region_1,4(1088,546.2)；

Step 15, according to the obtained barycenter pixel coordinate value (1154,696)₁The coded values of all the coded mark circles in the parallelogram coding unit are calculated to obtain a unit binary image E without a complex background₁The pixel coordinate value of the middle mass center is (1154,696)₁The coding number W of the parallelogram coding unit on the coding plane target placed in the actual space corresponding to the parallelogram coding unit₁The method comprises the following specific steps:

step 15.1, binarizing the image E in the 1 st unit without complex background₁According to the obtained coordinate value of the pixel at the centroid as (1154,696)₁Is marked with an angular point C of the 1 st coding region in the parallelogram coding unit_1,1(1333,546.2), calibration corner point C of the 6 th encoding region_1,4(1088,546.2) the centroid coordinate is (1154,696) from equation (13)₁The 5 th decision vector in the parallelogram coding unit of

Comprises the following steps:

while recording the vector

The straight line is l_1,3；

Binarizing image E in 1 st unit without complex background₁The coordinate value of the centroid pixel is (1154,696)₁Positioning circle center of mass o 'of parallelogram encoding unit'_l,1(1211,621) as a starting point with a 5 th decision vector

Parallel and co-directional unit vectors, denoted as

And recording unit vector

The straight line is l_1,1The coordinate value of the centroid pixel is (1154,696)₁Of parallelogram-shaped coding units of (1)'_d,1(1211,715) as a starting point with a 5 th decision vector

Parallel and co-directional unit vectors, denoted as

And recording the straight line of the unit vector as l_1,2(ii) a Re-assigning the integer variable i to 1;

step 15.2, defining 6 floating point type two-dimensional arrays Cr₁ ¹[2][2]、Cr₁ ²[2][2]、Cr₁ ³[2][2]、Cr₁ ⁴[2][2]、Cr₁ ⁵[2][2]、Cr₁ ⁶[2][2]For storing the pixel coordinate value of centroid as(1154,696)₁The coding mark circular contour centroid of the parallelogram coding unit respectively positioned in the 1 st coding region, the 2 nd coding region, the 3 rd coding region, the 4 th coding region, the 5 th coding region and the 6 th coding region in the 1 st unit binary image E without complex background₁Initializing all elements in the 6 two-dimensional arrays according to the pixel coordinates, and assigning the values to be-1; taking 6 integer variables

And it is initialized by the computer system to be initialized,

re-assigning the integer variable i to 1;

step 15.3, binarizing the image E in the 1 st unit without complex background₁Calculating the centroid pixel coordinate value is (1154,696)₁In a parallelogram coding unit of

Centroid pixel coordinates of

And

respectively with the center of mass o 'of the positioning circle'_l,1Oriented ring centroid o'_d,1Formed 1 st group of 1 st quadrant vectors

And group 1,2 nd quadrant vector

And group 2 quadrant 1 vectors

And group 2 quadrant 2 vectors

According to the calculated 1 st group of 1 st quadrant vectors

And group 1,2 nd quadrant vector

Group 2, quadrant 1 vectors

And group 2 quadrant 2 vectors

Unit vector

And

and a direction vector

Calculated by the following equations (16), (17), (18) and (19)

And

the results are as follows:

the pixel coordinate value at the mass center is (1154,696)₁In the parallelogram coding unit of (1), the judgment result of the coding region to which the coding flag circle belongs is as follows:

coded marker circle profile

The coordinate value of the pixel falling on the centroid is (1154,696)₁The 1 st coding region of the parallelogram coding unit of (1); order to

Coded marker circle profile

The coordinate value of the pixel falling on the centroid is (1154,696)₁The 2 nd coding region of the parallelogram coding unit of (1); order to

Step 15.4, define

The coordinate value of the representative centroid pixel is (1154,696)₁The code value of the w-th bit of the flag circle (where w is 1,2) in the λ -th code region (where λ is 1,2,3,4,5,6) in the parallelogram coding unit of (1),

taking 0 or 1; taking an integer variable i, and endowing the i with an initial value i which is 1 again;

step 15.5, in this embodiment, according to this step, can obtain:

and is

Satisfy the requirement of

Then

And is

Satisfy the requirement of

Then

Step 15.6, in this embodiment, the following steps can be obtained:

then

Then

Step 15.7, in a specific embodiment, this step can result in:

then

Then

Step 15.8, the coordinate value of the centroid pixel obtained by the steps is (1154,696)₁The coded values of all the coded mark circles in the parallelogram coding unit can be obtained by the formula (23) from the 1 st unit binary image E without complex background₁The center of mass pixel coordinate is a value (1154,696)₁The coding number W of the parallelogram coding unit on the coding plane target placed in the actual space corresponding to the parallelogram coding unit₁Comprises the following steps: w₁＝V₁ ^TU ═ 10; wherein, the column vector U is (2)⁰,2¹,2²,...2¹¹)^TColumn vector V₁＝(0,1,0,1,0,0,0,0,0,0,0,0)^T；

Step 16, recording the unit binary image E of the 1 st non-complex background₁The coordinate value of the upper centroid pixel is (1154,696)₁The non-unique code number of the calibration corner point belonging to the sigma-th coding region (where sigma is 1,3,4,6) in the parallelogram coding unit of (a) is L₁₀ ^σWherein the lower foot mark 10 is a calibration corner point L₁₀ ^σThe coding number of the parallelogram coding unit, the value of the upper corner mark sigma represents the calibration corner point L₁₀ ^σThe sigma-th coding region; that is, the coordinates of the centroid pixel are obtained as (1154,696)₁4 calibration angular points C on the parallelogram coding unit_1,1(1333,546.2)、C_1,2(1333,790.8)、C_1,3(1088,790.8)、C_1,4(1088,546.2) the non-unique code numbers are each

(where σ_1,1＝1,σ_1,2＝3,σ_1,3＝4,σ_1,4＝6)；

Step 17, obtaining the 1 st unit binary image E without complex background₁The coordinate value of the upper centroid pixel is (1154,696)₁On the basis of the non-unique code serial numbers of the 4 calibration angular points of the parallelogram coding unit, the unique code serial numbers of the 4 calibration angular points are calculated through the following specific steps:

step 17.1, take Delta'_1,1_σ′_1,1、Δ′_1,2_σ′_1,2、Δ′_1,3_σ′_1,3、Δ′_1,4_σ′_1,4Respectively used for storing the coordinates of the mass center as (1154,696)₁4 calibration angular points C on the parallelogram coding unit_1,1(1333,546.2)、C_1,2(1333,790.8)、C_1,3(1088,790.8)、C_1,4(1088,546.2) a unique code number, wherein Δ'_1,1、Δ′_1,2、Δ′_1,3、Δ′_1,4、σ′_1,1、σ′_1,2、σ′_1,3、σ′_1,4Are all positive integers;

step 17.2, taking an integer variable i and re-assigning the value of i to 1;

step 17.3, in this embodiment, if N is equal to 12 and is an even number, then the integer parameter Δ is taken and assigned with Δ N/2 is equal to 6, and the corner point C is calibrated_1,i(x_1,i,y_1,i) Non-unique code number of

This step can be divided into the following cases:

case 1, if σ_1,i1 or σ_1,iTo 6, 10 is assigned to Δ'_1,iWill σ_1,iValue of to σ'_1,iThen calibrating the corner point C_1,i(x_1,i,y_1,i) Is 10_ σ'_1,i；

Case 2, if σ_1,iTo 3,4 is assigned to Δ'_1,iAssigning 6 to σ'_1,iThen calibrating the corner point C_1,i(x_1,i,y_1,i) The unique code number of (2) is 4_ 6;

case 3, if σ_1,iTo 4, assign 3 to Δ'_1,iAssigning 1 to σ'_1,iThen calibrating the corner point C_1,i(x_1,i,y_1,i) The unique code number of (2) is 3_ 1;

judging whether i is smaller than 4, if i is smaller than 4, assigning i +1 to i, and returning to the step 17.3 for sequential execution; otherwise, executing step 18;

thus, a 1 st unit binary image E without complex background is obtained₁The upper centroid pixel coordinate is (1154,696)₁The one-to-one correspondence relationship between the pixel coordinates of the 4 calibration corner points on the parallelogram coding unit and the unique coding serial number thereof is as follows:

calibrating angular point C_1,1(1333,546.2) the corresponding unique code number is 10_ 1;

calibrating angular point C_1,2(1333,790.8) the corresponding unique code number is 4_ 6;

calibrating angular point C_1,3(1088,790.8) the corresponding unique code number is 3_ 1;

calibrating angular point C_1,4(1088,546.2) the corresponding unique code number is 10_ 6;

step 18, establishing a target coordinate system O_t-X_tY_tZ_t(ii) a The specific process is as follows:

step 18.1, recording the number of calibration corner points in 4 vertexes of the 1 st parallelogram coding unit in the 1 st line as phi_pThen can be according to phi_pThe numerical values are classified into the following two cases:

case 1 when phi_pWhen 1, the 1 st parallelogram coding unit in the 1 st line is denoted

In as the origin calibration corner point alpha'₁At the moment, an origin is selected to mark the angular point alpha'₁Origin O as target coordinate system_tTo assist the vector

As a target coordinate system X_tThe direction of the axis;

case 2 when phi_pWhen 2, the 1 st parallelogram coding unit in the 1 st row is respectively marked

Is epsilon 'as two calibration corner points'₃And ε₃According to the calibrated corner point epsilon'₃And ε₃The positional relationship of (c) can be further classified into the following cases:

(1) when vector

Direction and auxiliary vector of

Is the same, the calibration corner point epsilon 'is selected at the moment'₃Origin O as target coordinate system_tTo assist the vector

Is taken as X of a target coordinate system_tThe direction of the axis;

(2) when vector

Direction and auxiliary vector of

When the directions of the two points are different, the calibration corner point epsilon' is selected at the moment₃Origin O as target coordinate system_tTo assist the vector

Is taken as X of a target coordinate system_tThe direction of the axis;

step 18.2, with forward vector

As Z of the target coordinate system_tDirection of axis, X of target coordinate system_tAxis, Z_tAxis and Y_tThe axis meets the right-hand criterion, so as to establish a target coordinate system O_t-X_tY_tZ_t；

Step 19, at the known centroid pixelThe coordinate is (1154,696)₁4 calibration angular points C on the parallelogram coding unit_1,1(1333,546.2)、C_1,2(1333,790.8)、C_1,3(1088,790.8)、C_1,4(1088,546.2) under the condition of the unique code serial numbers 10_1, 4_6, 3_1, and 10_6 of the coding plane target and the basic information of the coding plane target in the space, obtaining target coordinate values of the No. 10_1 calibration corner point, the No. 4_6 calibration corner point, the No. 3_1 calibration corner point, and the No. 10_6 calibration corner point by using a target coordinate calculation method of the calibration corner points on the coding plane target;

this step can be calculated to obtain:

pixel coordinate C of calibration corner point with unique code serial number of 10_1_1,1(1333,546.2) the target coordinate is (X)_1,1,Y_1,1,0)＝(168,24,0)；

Pixel coordinate C of calibration corner point with unique code serial number of 4_6_1,2(1333,790.8) the target coordinate is (X)_1,2,Y_1,2,0)＝(168,0,0)；

Pixel coordinate C of calibration corner point with unique code serial number of 3_1_1,3(1088,790.8) the target coordinate is (X)_1,3,Y_1,3,0)＝(144,0,0)；

Pixel coordinate C of calibration corner point with unique code serial number of 10_6_1,4(1088,546.2) the target coordinate is (X)_1,4,Y_1,4,0)＝(144,24,0)；

And step 20, assigning zeta +1 to zeta, and executing the steps 13 to 19 in a circulating manner until zeta is larger than 11, ending the circulating manner, and obtaining the target coordinate values of all the calibration corner points on 11 parallelogram coding units.

Therefore, according to all the steps, the gray image P of the plane target can be obtained and coded₁And target coordinates corresponding to the pixel coordinates of all calibration corner points in the polygon L with the maximum number of the calibration corner points are found, namely, the one-to-one correspondence relationship between the pixel coordinates of the selected calibration corner point and the target coordinates is found, and simultaneously, the unique coding serial number of the selected calibration corner point is also found, so that the decoding of the coding plane target is completed.

In this implementationIn the example, a 1 st unit binary image E without complex background is obtained by using a target coordinate calculation method of a calibration corner point on a coding plane target₁The coordinate value of the upper centroid pixel is (1154,696)₁The target coordinates corresponding to the pixel coordinates of the 4 calibration corner points on the parallelogram coding unit are as follows:

step 1, taking an integer variable i and re-assigning the value i to be 1;

step 2, if N is an even number, in this embodiment, step 2.1 is executed;

step 2.1, the step is divided into the following conditions:

case 1, if Δ'_1,i_σ′_1,iOf σ'_1,i1 ═ 1; then the code number is delta'_1,i_σ′_1,iThe target coordinates corresponding to the calibration corner points are as follows: (24. rho.)₁₀,24·δ₁₀,0)；

Case 2, if Δ'_1,i_σ′_1,iOf σ'_1,i6; then the code number is delta'_1,i_σ′_1,iThe target coordinates corresponding to the calibration corner points are as follows: (24. (. rho.)₁₀-1),24·δ₁₀,0)；

In this step, δ₁₀＝2Δ′_1,i13 (the result retains only integer bits);

when delta₁₀When it is odd, ρ₁₀＝{Δ′_1,i-[12·δ₁₀/2+(δ₁₀+1)/2]}·2+1；

When delta₁₀When it is even, ρ₁₀＝[Δ′_1,i-13·δ₁₀/2]·2；

Step 3, judging whether i is smaller than 4, if i is smaller than 4, assigning i +1 to i and returning to the step 2 for sequential execution; if i is larger than or equal to 4, obtaining target coordinates of the No. 10_1 calibration angular point, the No. 4_6 calibration angular point, the No. 3_1 calibration angular point and the No. 10_6 calibration angular point, and respectively recording the target coordinates as (X)_1,1,Y_1,1,0)、(X_1,2,Y_1,2,0)、(X_1,3,Y_1,3,0)、(X_1,4,Y_1,4,0)；

In the bookIn the examples:

thereby obtaining a centroid pixel coordinate of (1154,696)₁The target coordinate values corresponding to the pixel coordinate values of the 4 calibration corner points on the parallelogram coding unit.

In addition, the decoding method based on the encoding plane target provided by the invention needs to prepare a corresponding computer program and execute the program on a computer to realize the corresponding operation processing and logic control functions, so the invention also provides a computer readable storage medium comprising the computer program used in combination with an electronic device with an image processing function, and the computer program can be executed by a processor to realize the decoding method.

The above description is only an embodiment of the present invention, and not intended to limit the scope of the present invention, and all modifications of equivalent structures and equivalent processes performed by the present specification and drawings, or directly or indirectly applied to other related technical fields, are included in the scope of the present invention.

Claims (16)

1. A method for decoding a coded planar target for camera calibration, comprising: the method comprises the following main steps:

step 1.1, inputting basic information of a coding plane target placed in a space, namely, the coding plane target in the space comprises M rows multiplied by N columns of calibration angular points, and the coding number of an initial parallelogram coding unit of the coding plane target is z_vThe number phi of the calibration corner points in 4 vertexes of the 1 st parallelogram coding unit in the 1 st line on the coding plane target_p；

Step 1.2, shooting the coding plane target located in the space through a camera, and obtaining an image of the coding plane target;

step 2, carrying out 8-bit gray level processing on the coding target image, and recording the obtained image as a coding plane target gray level image P₁；

Step 3, establishingCalibrating the pixel coordinate system of the angular point, and coding the gray image P of the plane target₁In the method, a checkerboard corner extraction algorithm is used for extracting a gray level image P of a coding plane target₁The sub-pixel coordinate set of m lines multiplied by n columns of calibration angular points with the largest number of calibration angular points is recorded as a calibration angular point sub-pixel coordinate set Q, and a polygon surrounded by the outermost angular points in the m lines multiplied by n columns of calibration angular point sub-pixel coordinate set is recorded as a maximum calibration angular point number polygon L;

step 4, in the said coded plane target gray image P₁In the method, the gray values of all the pixel points in the maximum calibration corner point polygon L are kept unchanged by using a digital image processing method, the gray values of all the pixel points except the maximum calibration corner point polygon L are assigned to be 255, and the gray image P of the coding plane target is assigned₁The image obtained by the processing is recorded as a gray level image P 'without a complex background target'₁；

Step 5, carrying out gray level image P 'without complex background target'₁Performing binarization processing, and obtaining a grayscale image P 'without a complex background target'₁Marking the image obtained by binarization as a binary image P without a complex background target₂；

6, according to the gray image P of the coded plane target₁The number of m rows multiplied by n columns of calibration angular points is contained in the extracted maximum calibration angular point number polygon L, and the number mu of parallelogram coding units contained in the maximum calibration angular point number polygon L is determined, wherein m, n and mu are integers;

step 7, binarizing the image P on the target without the complex background₂Performing black connected domain corrosion treatment to ensure that no complex background target binaryzation image P₂All the parallelogram coding units are disconnected at the diagonal positions, and the complex background-free target binary image P is obtained₂The image obtained by the processing is marked as a target binaryzation corrosion image P'₂；

Step 8, finding binaryzation corrosion image P 'in target'₂And the mu maximum black connected domains in the image are respectively marked as grid connected domains omega₁Grid connected domain omega₂…, grid connected domain omega_μCalculating to obtain a target binarization corrosion image P'₂Upper square connected domain omega₁Grid connected domain omega₂…, grid connected domain omega_μCentroid pixel coordinate (x)₁,y₁)₁、(x₂,y₂)₂、…、(x_μ,y_μ)_μAnd will be (x)₁,y₁)₁、(x₂,y₂)₂、…、(x_μ,y_μ)_μSequentially serving as a 1 st element, a 2 nd element, … and a mu th element in a parallelogram coding unit centroid pixel coordinate set A;

step 9, binarizing the corrosion image P 'on the target'₂In the method, a target binarization corrosion image P 'is obtained through calculation'₂Of (1) ring center connected region omega'₁And omega 'of circular ring center connected region'₂…, ring center connected region omega'_μ；

Step 10, binarizing the corrosion image P 'on the target'₂In the method, a target binarization corrosion image P 'is obtained through calculation'₂Of (1) ring center connected region omega'₁And omega 'of circular ring center connected region'₂…, ring center connected region omega'_μCentroid pixel coordinate o ″)_d,1(x″_d,1,y″_d,1)、o″_d,2(x″_d,2,y″_d,2)、…、o″_d,μ(x″_d,μ,y″_d,μ) And will o ″)_d,1(x″_d,1,y″_d,1)、o″_d,2(x″_d,2,y″_d,2)、…、o″_d,μ(x″_d,μ,y″_d,μ) Sequentially serving as a 1 st element, a 2 nd element, … and a mu th element in the circular ring centroid pixel coordinate set B;

step 11, binarizing the corrosion image P 'on the target'₂In, will remove square connected domain omega₁Grid connected domain omega₂…, grid connected domain omega_μAnd a circular ring center connected region omega'₁And omega 'of circular ring center connected region'₂…, ring center connected region omega'_μGray values of other black connected domainsAssigning value to be 255, and binarizing the target to obtain a corrosion image P'₂The image obtained by the processing is recorded as a decoded binary image P₃；

Step 12, taking an integer variable zeta, and giving an initial value zeta as 1;

step 13, removing the complex background except the zeta-th parallelogram coding unit to obtain a zeta-th unit binary image E without the complex background_ζ；

Step 14, binarizing the image E in the zeta th unit without complex background_ζSearching for a calibration angular point of the zeta-th parallelogram coding unit, and determining a coding region corresponding to the calibration angular point;

step 15, obtaining the coordinate value of the centroid pixel as (x)_ζ,y_ζ)_ζThe coded values of all the coded mark circles in the parallelogram coding unit are obtained, and a unit binary image E without a complex background with the Zeth unit is obtained_ζThe central pixel coordinate value is (x)_ζ,y_ζ)_ζThe coding number W of the parallelogram coding unit on the coding plane target placed in the actual space corresponding to the parallelogram coding unit_ζ；

Step 16, obtaining the zeta unit binary image E without complex background_ζThe center of mass pixel coordinate is (x)_ζ,y_ζ)_ζ4 calibration angular points C on the parallelogram coding unit_ζ,1(x_ζ,1,y_ζ,1)、C_ζ,2(x_ζ,2,y_ζ,2)、C_ζ,3(x_ζ,3,y_ζ,3)、C_ζ,4(x_ζ,4,y_ζ,4) A non-unique code number of (a);

step 17, calculating to obtain the zeta unit binary image E without complex background_ζThe center of mass pixel coordinate is (x)_ζ,y_ζ)_ζ4 calibration angular points C on the parallelogram coding unit_ζ,1(x_ζ,1,y_ζ,1)、C_ζ,2(x_ζ,2,y_ζ,2)、C_ζ,3(x_ζ,3,y_ζ,3)、C_ζ,4(x_ζ,4,y_ζ,4) Is only oneA code number;

step 18, establishing a target coordinate system O_t-X_tY_tZ_t；

Step 19, obtaining the zeta unit binary image E without complex background by using the target coordinate calculation method of the calibration corner point on the coding plane target_ζThe center of mass pixel coordinate is (x)_ζ,y_ζ)_ζTarget coordinate values of 4 calibration angular points on the parallelogram coding unit; that is, the centroid pixel coordinate is obtained as (x)_ζ,y_ζ)_ζThe matching relation among the sub-pixel coordinates, the unique coding numbers and the target coordinates of the 4 calibration corner points on the parallelogram coding unit is as follows:

unique code number of delta'_ζ,1_σ′_ζ,1Pixel coordinate C of the calibration corner point_ζ,1(x_ζ,1,y_ζ,1) The corresponding target coordinate is (X)_ζ,1,Y_ζ,1,0)；

Unique code number of delta'_ζ,2_σ′_ζ,2Pixel coordinate C of the calibration corner point_ζ,2(x_ζ,2,y_ζ,2) The corresponding target coordinate is (X)_ζ,2,Y_ζ,2,0)；

Unique code number of delta'_ζ,3_σ′_ζ,3Pixel coordinate C of the calibration corner point_ζ,3(x_ζ,3,y_ζ,3) The corresponding target coordinate is (X)_ζ,3,Y_ζ,3,0)；

Unique code number of delta'_ζ,4_σ′_ζ,4Pixel coordinate C of the calibration corner point_ζ,4(x_ζ,4,y_ζ,4) The corresponding target coordinate is (X)_ζ,4,Y_ζ,4,0)；

And 20, endowing zeta +1 with zeta, and circularly executing the steps 13 to 19 to obtain target coordinate values of all calibration corner points on the mu parallelogram coding units.

2. The method of claim 1, wherein the method comprises the following steps: in step 13, the ζ th background-freeUnit binary image E_ζThe method comprises the following specific steps:

step 13.1, decoding the binary image P₃Copying and backing up, and recording the copied image as the zeta-th backup binary image P_ζ,4；

Step 13.2, backup binarization image P at the zeta th_ζ,4Taking the Zeth centroid pixel coordinate value (x) in the centroid pixel coordinate set A of the parallelogram coding unit_ζ,y_ζ)_ζFinding out the pixel coordinate value (x) of distance centroid in the calibration corner point set Q_ζ,y_ζ)_ζPixel coordinate values of the nearest 4 calibration corner points, and setting the pixel coordinate values of the 4 calibration corner points in the ζ -th backup binary image P_ζ,4The corresponding 4 pixel points are respectively marked as C ″)_ζ,1(x″_ζ,1,y″_ζ,1)、C″_ζ,2(x″_ζ,2,y″_ζ,2)、C″_ζ,3(x″_ζ,3,y″_ζ,3)、C″_ζ,4(x″_ζ,4,y″_ζ,4) (ii) a And taking the 4 pixel points as a zeta-th calibration corner point quadrangle S_ζAnd connecting the 4 vertexes to form a zeta-th calibration corner point quadrangle S_ζ；

Step 13.3, finding out the Zeth centroid pixel coordinate value (x) in the centroid pixel coordinate set A of the parallelogram coding unit from the circular ring centroid pixel coordinate set B_ζ,y_ζ)_ζThe corresponding zeta th ring centroid pixel coordinate value (x ″)_d,ζ,y″_d,ζ)；

Step 13.4, backup binarization image P at the zeta th_ζ,4In the method, the coordinate value (x ″) of the pixel of the center of mass of the ring is searched_d,ζ,y″_d,ζ) The nearest white connected domain, and the gray value of the white connected domain is assigned to be 0;

step 13.5, backup binarization image P at the zeta th_ζ,4In the above, the Zeta th calibration corner point quadrangle S_ζExcept that the gray values of all the pixel points are assigned to be 255, and the zeta-th calibration corner point quadrangle S_ζThe gray values of all the internal pixel points are kept unchanged.

3. The method of claim 1, wherein the method comprises the following steps: in step 14, binarized image E is obtained in the ζ -th unit without complex background_ζIn the method, a specific method for finding a calibration corner of the ζ -th parallelogram coding unit and determining a coding region to which the corresponding calibration corner belongs is as follows:

step 14.1, binarizing the image E in the zeta th unit without complex background_ζIn the binary image, the maximum black connected domain is searched and marked as the zeta th unit binary image without complex background_ζMaximum black connected component Ω in_ζ,E(ii) a Extracting the Zeth unit binary image E without complex background_ζMaximum black connected component Ω in_ζ,EAnd is recorded as a centroid pixel coordinate value of (x)_ζ,y_ζ)_ζOf a parallelogram-shaped coding unit D_ζ；

Step 14.2, the coordinates of the centroid pixel are the value (x)_ζ,y_ζ)_ζOf a parallelogram-shaped coding unit D_ζIn the method, the number of pixel points included in each contour is counted, wherein the contour including the second most pixel points is the unit binary image E without the complex background at the zeta th_ζThe centroid pixel coordinate value of (x)_ζ,y_ζ)_ζIn a parallelogram coding unit of (2) an outline G of a positioning circle_ζCalculating the positioning circle profile G_ζAnd is recorded as a unit binary image E without complex background at the zeta th position_ζThe centroid pixel coordinate value of (x)_ζ,y_ζ)_ζLocate circle centroid pixel coordinate o 'in parallelogram coding unit of (1)'_l,ζ(x′_l,ζ,y′_l,ζ)；

Step 14.3, coordinate of mass center is (x)_ζ,y_ζ)_ζOf a parallelogram-shaped coding unit D_ζIn (1), the 2 contours with the largest number of pixels are removed, and the remaining k_ζThe outline is a sheet without complex background at the zeta thMeta-binary image E_ζThe centroid pixel coordinate value of (x)_ζ,y_ζ)_ζThe coded mark circle contour in the parallelogram coding unit is recorded as the coded mark circle contour

Coded marker circle profile

… coded marker circle outline

Wherein κ_ζ＝0,1,2,3...；

Step 14.4, assigning the initial value i to the integer variable i again, wherein the initial value i is 1;

step 14.5, binarizing the image E in the zeta th unit without complex background_ζIn, calculating the circular contour of the code mark

Centroid pixel coordinates of

This step continues after i +1 is reassigned to i until i > κ_ζAnd finishing, obtaining the coordinate value of the centroid pixel as (x)_ζ,y_ζ)_ζCoded flag circle contour in parallelogram coding unit of

Coded marker circle profile

… coded marker circle outline

Centroid pixel coordinates of

Step 14.6, binarizing the image E in the zeta th unit without complex background_ζThe pixel coordinate value is (x ″)_d,ζ,y″_d,ζ) The pixel point is marked as the coordinate value of the centroid pixel as (x)_ζ,y_ζ)_ζOf parallelogram-shaped coding units of (2) oriented circular ring centroid o'_d,ζ(x′_d,ζ,y′_d,ζ) (ii) a And binarizing the image E at the ζth unit without complex background_ζThe pixel coordinate values are (x ″)_ζ,1,y″_ζ,1)、(x″_ζ,2,y″_ζ,2)、(x″_ζ,3,y″_ζ,3)、(x″_ζ,4,y″_ζ,4) And 4 pixel points are recorded as C'_ζ,1(x′_ζ,1,y′_ζ,1)、C′_ζ,2(x′_ζ,2,y′_ζ,2)、C′_ζ,3(x′_ζ,3,y′_ζ,3)、C′_ζ,4(x′_ζ,4,y′_ζ,4)；

Step 14.7, binarizing the image E in the zeta th unit without complex background_ζUpper, get C_ζ,1(x_ζ,1,y_ζ,1)、C_ζ,2(x_ζ,2,y_ζ,2)、C_ζ,3(x_ζ,3,y_ζ,3)、C_ζ,4(x_ζ,4,y_ζ,4) Respectively expressed in coordinates of centroid as (x)_ζ,y_ζ)_ζThe pixel coordinates of the calibration corner points of the No. 1 coding region, the No. 3 coding region, the No. 4 coding region and the No. 6 coding region in the parallelogram coding unit; positioning circle centroid pixel coordinate o'_l,ζ(x′_l,ζ,y′_l,ζ) And a directional ring centroid o'_d,ζ(x′_d,ζ,y′_d,ζ) The coordinate value of the centroid pixel is calculated as (x)_ζ,y_ζ)_ζIn a parallelogram coding unit

Step 14.8, binarizing the image E in the zeta th unit without complex background_ζLast, 4 pixel points C'_ζ,1(x′_ζ,1,y′_ζ,1)、C′_ζ,2(x′_ζ,2,y′_ζ,2)、C′_ζ,3(x′_ζ,3,y′_ζ,3)、C′_ζ,4(x′_ζ,4,y′_ζ,4) Medium-distance positioning circle center of mass o'_l,ζ(x′_l,ζ,y′_l,ζ) The nearest 2 pixels are respectively marked as C_ζ,1min(x_ζ,1min,y_ζ,1min) And C_ζ,2min(x_ζ,2min,y_ζ,2min) (ii) a Respectively calculating the coordinate value of the centroid pixel as (x)_ζ,y_ζ)_ζ1 st decision vector in a parallelogram coding unit of

And 2 nd decision vector

And a region division sine value 1sin alpha_ζSum region dividing sine value 2sin beta_ζ(ii) a According to sin alpha_ζAnd sin beta_ζDetermining the coordinate value of the heart pixel as (x)_ζ,y_ζ)_ζThe calibration corner points of the 1 st coding region and the 6 th coding region in the parallelogram coding unit are calibrated;

step 14.9, binarizing the image E in the zeta th unit without complex background_ζBy having found the centroid pixel coordinate value of (x)_ζ,y_ζ)_ζThe calibration corner points C of the 1 st coding region and the 6 th coding region in the parallelogram coding unit_ζ,1(x_ζ,1,y_ζ,1) And C_ζ,4(x_ζ,4,y_ζ,4) C 'will be 4 pixel points'_ζ,1(x′_ζ,1,y′_ζ,1)、C′_ζ,2(x′_ζ,2,y′_ζ,2)、C′_ζ,3(x′_ζ,3,y′_ζ,3)、C′_ζ,4(x′_ζ,4,y′_ζ,4) The pixel coordinates of the rest 2 pixel points are respectively assigned to the centroid pixel coordinate value of (x)_ζ,y_ζ)_ζThe 1 st temporary coordinate value of the parallelogram coding unit of (1) is denoted as C'_ζ,5(x′_ζ,5,y′_ζ,5) And the 2 nd temporary coordinate value, denoted as C'_ζ,6(x′_ζ,6,y′_ζ,6) (ii) a According to the calculated coordinate value of the centroid pixel as (x)_ζ,y_ζ)_ζOf the parallelogram coding unit of (3) th decision vector

And 4 th judgment vector

Step 14.10, judging the vector according to the No. 3

And 4 th judgment vector

Obtaining the region dividing sine value 3sin omega_ζSum region dividing sine value 4sin xi_ζ(ii) a According to sin ω_ζAnd sin xi_ζDetermining the pixel coordinate value as (x)_ζ,y_ζ)_ζThe 3 rd coding region and the 4 th coding region in the parallelogram coding unit.

4. The method of claim 1, wherein the method comprises the following steps: in step 15, the centroid pixel coordinate value is determined to be (x)_ζ,y_ζ)_ζNumber W of parallelogram-shaped coding unit of (1)_ζThe specific method comprises the following steps:

step 15.1, binarizing the image E in the zeta th unit without complex background_ζAccording to the natureThe coordinate value of the heart pixel is (x)_ζ,y_ζ)_ζIs marked with an angular point C of the 1 st coding region in the parallelogram coding unit_ζ,1(x_ζ,1,y_ζ,1) Calibration corner point C of the 6 th coding region_ζ,4(x_ζ,4,y_ζ,4) Obtaining the coordinate value of the centroid pixel as (x)_ζ,y_ζ)_ζThe 5 th decision vector in the parallelogram coding unit of

The coordinate value of the centroid pixel is (x)_ζ,y_ζ)_ζPositioning circle center of mass o 'of parallelogram encoding unit'_l,ζ(x′_l,ζ,y′_l,ζ) Make the 5 th judgment vector as the starting point

Parallel and co-directional unit vectors

The coordinate value of the centroid pixel is (x)_ζ,y_ζ)_ζOf parallelogram-shaped coding units of (1)'_d,ζ(x′_d,ζ,y′_d,ζ) Make the 5 th judgment vector as the starting point

Parallel and co-directional unit vectors

Re-assigning the integer variable i to 1;

step 15.2, defining 6 floating point type two-dimensional arrays

For storing the value of the centroid pixel coordinate as (x)_ζ,y_ζ)_ζThe coding mark circular contour centroid of the parallelogram coding units in the No. 1 coding area, the No. 2 coding area, the No. 3 coding area, the No. 4 coding area, the No. 5 coding area and the No. 6 coding area is in the Zeth unit binary image without complex background_ζInitializing all elements in the 6 two-dimensional arrays according to the pixel coordinates, and assigning the values to be-1; taking 6 integer variables

And it is initialized by the computer system to be initialized,

step 15.3, binarizing the image E in the zeta th unit without complex background_ζCalculating the centroid pixel coordinate value as (x)_ζ,y_ζ)_ζIn a parallelogram coding unit of

Centroid pixel coordinates of

Respectively with the center o 'of the positioning circle'_l,ζAnd a directional ring center o'_d,ζThe formed ith group of 1 st quadrant vectors

And ith group of 2 nd quadrant vectors

According to

And

unit vector

And

and a direction vector

Respectively calculate

And according to

Respectively judging that the coordinate value of the centroid pixel is (x)_ζ,y_ζ)_ζIn the parallelogram coding unit of (1), coding the coding region to which the marker circle belongs;

step 15.4, according to the calculation

Determining the centroid pixel coordinate value as (x)_ζ,y_ζ)_ζThe code values of all the code flag circles in the parallelogram coding unit of (1);

step 15.5, calculating the coordinate value of the centroid pixel as (x)_ζ,y_ζ)_ζNumber W of parallelogram-shaped coding unit of (1)_ζ。

5. The method of claim 1, wherein the method comprises the following steps: in step 16, the ζ th unit binary image E without complex background is obtained_ζThe center of mass pixel coordinate is (x)_ζ,y_ζ)_ζ4 calibration angular points C on the parallelogram coding unit_ζ,1(x_ζ,1,y_ζ,1)、C_ζ,2(x_ζ,2,y_ζ,2)、C_ζ,3(x_ζ,3,y_ζ,3)、C_ζ,4(x_ζ,4,y_ζ,4) The method of the non-unique code number of (2) is as follows:

zeta-th unit binary image E without complex background_ζThe upper centroid pixel coordinate value is (x)_ζ,y_ζ)_ζThe non-unique coding number of the calibration corner point belonging to the sigma-th coding region (where sigma is 1,3,4,6) in the parallelogram coding unit of (1) is

Wherein the lower foot mark W_ζFor calibrating angular points

The coding number of the parallelogram coding unit, and the value of the upper corner mark sigma represents the calibration corner point

The sigma-th coding region; that is, the coordinates of the centroid pixel are obtained as (x)_ζ,y_ζ)_ζ4 calibration angular points C on the parallelogram coding unit_ζ,1(x_ζ,1,y_ζ,1)、C_ζ,2(x_ζ,2,y_ζ,2)、C_ζ,3(x_ζ,3,y_ζ,3)、C_ζ,4(x_ζ,4,y_ζ,4) Respectively has a non-unique code number of

(where σ_ζ,1＝1,σ_ζ,2＝3,σ_ζ,3＝4,σ_ζ,4＝6)。

6. The method of claim 1, wherein the method comprises the following steps: in step 17, the ζ th unit binary image E without complex background is obtained by calculation_ζThe center of mass pixel coordinate is (x)_ζ,y_ζ)_ζ4 calibration angular points C on the parallelogram coding unit_ζ,1(x_ζ,1,y_ζ,1)、C_ζ,2(x_ζ,2,y_ζ,2)、C_ζ,3(x_ζ,3,y_ζ,3)、C_ζ,4(x_ζ,4,y_ζ,4) The specific steps of the unique code number are as follows:

step 17.1, take Delta'_ζ,1_σ′_ζ,1、Δ′_ζ,2_σ′_ζ,2、Δ′_ζ,3_σ′_ζ,3、Δ′_ζ,4_σ′_ζ,4Respectively used for storing the coordinate value of the centroid pixel as (x)_ζ,y_ζ)_ζ4 calibration angular points C on the parallelogram coding unit_ζ,1(x_ζ,1,y_ζ,1)、C_ζ,2(x_ζ,2,y_ζ,2)、C_ζ,3(x_ζ,3,y_ζ,3)、C_ζ,4(x_ζ,4,y_ζ,4) Is unique code number of, wherein'_ζ,1、Δ′_ζ,2、Δ′_ζ,3、Δ′_ζ,4、σ′_ζ,1、σ′_ζ,2、σ′_ζ,3、σ′_ζ,4Are all positive integers;

step 17.2, taking an integer variable i and re-assigning the value of i to 1;

step 17.3, judging according to the parity of N, and if N is an even number, executing step 17.4; if N is odd, go to step 17.5;

step 17.4, taking the integer parameter delta, assigning the value delta to be N/2, and calibrating the corner point C_ζ,i(x_ζ,i,y_ζ,i) Non-unique code number of

This step 17.4 can be divided into the following cases:

case 1, if σ_ζ,i1 or σ_ζ,iWhen W is equal to 6, the product is put in_ζValue of to delta'_ζ,iWill σ_ζ,iValue of to σ'_ζ,iThen calibrating the corner point C_ζ,i(x_ζ,i,y_ζ,i) Is delta 'as the unique code number'_ζ,i_σ′_ζ,i；

Case 2, if σ_ζ,i(W) 3 ═ 3_ζValue of- Δ) to Δ'_ζ,iAssigning 6 to σ'_ζ,iThen calibrating the corner point C_ζ,i(x_ζ,i,y_ζ,i) Is delta 'as the unique code number'_ζ,i_6；

Case 3, if σ_ζ,i(W) is 4 ═ 4_ζValue of-Delta-1) to Delta'_ζ,iAssigning 1 to σ'_ζ,iThen calibrating the corner point C_ζ,i(x_ζ,i,y_ζ,i) Is delta 'as the unique code number'_ζ,i_1；

Judging whether i is smaller than 4, if i is smaller than 4, assigning i +1 to i, and returning to the step 17.4 to execute in sequence; otherwise, finishing the calculation of the unique coding serial number of the calibration angular point;

step 17.5, taking the integer parameter delta, assigning the value delta to be (N +1)/2, and calibrating the corner point C_ζ,i(x_ζ,i,y_ζ,i) Non-unique code number of

This step 17.5 can be divided into the following cases:

case 1, if σ_ζ,i1 or σ_ζ,iWhen W is equal to 6, the product is put in_ζValue of to delta'_ζ,iWill σ_ζ,iValue of to σ'_ζ,iThen calibrating the corner point C_ζ,i(x_ζ,i,y_ζ,i) Is delta 'as the unique code number'_ζ,i_σ′_ζ,i；

Case 2, if σ_ζ,iWhen the value is 3, the following two cases are divided into:

(1) when phi is_pWhen the value is 1, (W) is_ζValue of- Δ ') to Δ'_ζ,iAssigning 6 to σ'_ζ,iThen calibrating the corner point C_ζ,i(x_ζ,i,y_ζ,i) Is delta 'as the unique code number'_ζ,i_σ′_ζ,i(ii) a Wherein

Δ″＝2(W_ζ-z_v) V (N +1) +1 (integers only retained);

(2) when phi is_pWhen being equal to 2, (W) is_ζA value of- Δ' ")Is assigned to delta'_ζ,iAssigning 6 to σ'_ζ,iThen calibrating the corner point C_ζ,i(x_ζ,i,y_ζ,i) Is delta 'as the unique code number'_ζ,i_σ′_ζ,i(ii) a Wherein

Δ″＝2(W_ζ-z_v+1)/(N +1) +1 (integers only retained);

case 3, if σ_ζ,iThe following two cases are divided into two cases:

(1) when phi is_pWhen the value is 1, (W) is_ζValue of- Δ ') to Δ'_ζ,iAssigning 1 to σ'_ζ,iThen calibrating the corner point C_ζ,i(x_ζ,i,y_ζ,i) Is delta 'as the unique code number'_ζ,i_σ′_ζ,iWherein

Δ″＝2(W_ζ-z_v) V (N +1) +1 (integers only retained);

(2) when phi is_pWhen being equal to 2, (W) is_ζValue of- Δ '") to Δ'_ζ,iAssigning 1 to σ'_ζ,iThen calibrating the corner point C_ζ,i(x_ζ,i,y_ζ,i) Is delta 'as the unique code number'_ζ,i_σ′_ζ,iWherein

Δ″＝2(W_ζ-z_v+1)/(N +1) +1 (integers only retained);

judging whether i is smaller than 4, if i is smaller than 4, assigning i +1 to i, and returning to the step 17.5 for sequential execution; otherwise, finishing the calculation of the unique coding serial number of the calibration corner point.

7. The method of claim 1, wherein the method comprises the following steps: in step 19, the Zeta th uncomplicated corner is obtained by using the target coordinate calculation method of the calibration corner point on the coding plane targetUnit binary image E of background_ζThe center of mass pixel coordinate is (x)_ζ,y_ζ)_ζThe specific steps of the target coordinate values of the 4 calibration corner points on the parallelogram coding unit are as follows:

step 19.1, taking an integer variable i and re-assigning the value of i to 1;

step 19.2, judging whether N is an even number, if N is an odd number, executing step 19.3; if N is an even number, the step is divided into the following cases:

case 1, if Δ'_ζ,i_σ′_ζ,iOf σ'_ζ,i1 ═ 1; then the unique code number is delta'_ζ,i_σ′_ζ,iThe target coordinates corresponding to the calibration corner points are as follows:

wherein when

When taken, when

Taking-;

case 2, if Δ'_ζ,i_σ′_ζ,iOf σ'_ζ,i6; then the unique code number is delta'_ζ,i_σ′_ζ,iThe target coordinates corresponding to the calibration corner points are as follows:

wherein when

When taken, when

Taking-;

in this step 19.2, the process is now described,

(the result retains only integer bits);

when in use

In the case of an odd number of the groups,

when in use

In the case of an even number, the number of the first,

after the execution of the step is finished, directly executing a step 19.4;

step 19.3, the step is divided into the following two cases:

case 1, if Δ'_ζ,i_σ′_ζ,iOf σ'_ζ,i1 ═ 1; then the unique code number is delta'_ζ,i_σ′_ζ,iThe target coordinates corresponding to the calibration corner points are as follows:

wherein when

When taken, when

Taking-;

case 2, if Δ'_ζ,i_σ′_ζ,iOf σ'_ζ,i6; then the unique code number is delta'_ζ,i_σ′_ζ,iThe target coordinates corresponding to the calibration corner points are as follows:

wherein when

When taken, when

Taking-;

in this step 19.3

(the result retains only integer bits);

when in use

In the case of an odd number of the groups,

when in use

In the case of an even number, the number of the first,

step 19.4, judging whether i is smaller than 4, if i is smaller than 4, assigning i +1 to i and returning to the step 19.2 to execute in sequence; if i is more than or equal to 4, finishing the coordinates of the centroid pixel as (x)_ζ,y_ζ)_ζAnd calculating target coordinate values of 4 calibration corner points on the parallelogram coding unit.

8. An encoded planar target for camera calibration by the decoding method of claim 1, wherein: the coding plane target consists of coding checkerboards formed by alternating parallelogram coding units and parallelogram non-coding units, the coding plane target takes the intersection points of the parallelogram coding units connected with any opposite angle as the calibration angular points of the coding plane target, a coding pattern is arranged in each parallelogram coding unit in the coding plane target, the coding pattern comprises a positioning pattern, an orientation pattern and a coding mark pattern, and the coding mark pattern consists of a plurality of coding unit patterns; the judgment of the rotation direction of the coding plane target can be realized by the orientation pattern and the positioning pattern; the coding mark pattern is used for coding each calibration corner point in the coding plane target.

9. The encoding planar target for camera calibration according to claim 8, wherein: the positioning pattern, the orientation pattern and the coding unit pattern inside each parallelogram coding unit in the coding plane target are not overlapped and not communicated.

10. The encoding planar target for camera calibration according to claim 8, wherein: the background colors of all parallelogram coding units in the coding plane target are the same, the colors of all parallelogram non-coding units in the coding plane target are the same, and the background colors of all parallelogram coding units in the coding plane target and the colors of all parallelogram non-coding units have obvious difference.

11. The encoding planar target for camera calibration according to claim 8, wherein: the colors of all positioning patterns and all orientation patterns contained in all parallelogram coding units in the coding plane target are the same, and the colors of all the positioning patterns and all the orientation patterns are obviously different from the background colors of all the parallelogram coding units.

12. The encoding planar target for camera calibration according to claim 8, wherein: the color of all coding unit patterns contained in all parallelogram coding units in the coding plane target is the same as the background color of the parallelogram coding units or the color of the positioning pattern.

13. The encoding planar target for camera calibration according to claim 8, wherein: in each parallelogram coding unit on the coding plane target, the contour length of the positioning pattern in the parallelogram coding unit is larger than the contour length of all the coding mark patterns, and the contour length of the positioning pattern is smaller than the region contour length of the parallelogram coding unit.

14. The encoded planar target of claim 8, wherein: in the coding plane target, the positioning pattern, the orientation pattern and the coding mark pattern on the same parallelogram coding unit are all arranged inside the parallelogram coding unit, and the mass center of the positioning pattern and the mass center of the orientation pattern in the same parallelogram coding unit are all arranged near the mass center of the parallelogram coding unit.

15. The encoding planar target for camera calibration according to claim 8, wherein: in the coding plane target, the coding number of each parallelogram coding unit and the coding number of the calibration corner point are determined by position and color information analyzed by a coding plane target decoding method of all coding unit patterns in the coding parallelogram coding unit.

16. A computer-readable storage medium comprising a computer program for use in conjunction with an electronic device having image processing functionality, the computer program being executable by a processor to perform the decoding method of claim 1.

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