CN101476882A - Structured light three-dimensional detection method based on homography matrix - Google Patents

Abstract

The invention relates to a structured light three-dimension detection method based on homographic matrixes in the technical field of computer vision. The method is to utilize characteristic points in a gridiron pattern to acquire homographic matrixes of an imaging surface of a camera corresponding to a plane P1 and a plane P2 respectively, measure homographic matrixes corresponding to a projection plane of a projector and the imaging surface of the camera on the plane P1 and the plane P2 respectively, specify a linear equation of certain grating on the projection plane, acquire the imaging surface and a plane below a world coordinate system according to the homographic matrixes, establish the relation between the imaging surface and the plane under the world coordinate system, and acquire the position of each grating below the world coordinate system through relation transformation to acquire three-dimension information. The method can simply and conveniently measure world coordinates, avoids device dependency problems, and simplifies three-dimension detection operation under the condition of guaranteeing the precision.

Description

Structured light three-dimensional detection method based on homography matrix

Technical field

The present invention relates to a kind of detection method of field of measuring techniques, specifically is a kind of structured light three-dimensional detection method based on homography matrix.

Background technology

It is an important directions of computer vision research that the three-dimensional of object detects, and its target is exactly the accurate description that obtains the target object morphology.Structural light three-dimensional detect with its use simple, measure accurate, nondestructive advantage and obtained to use widely.Structured light three-dimensional detection method mainly is divided into two parts, and first is projecting structural optical and takes the acquisition structure light image, carries out the image two-dimensional signal that structured light decoding obtains structured light then; Second portion is the three-dimensional information that is converted into target object according to the image two-dimensional signal of the relative position bar structure light of projector, camera and target object.

Through the prior art literature search is found, Tsai R Y in one piece of article " A versatilecamera calibration technique for high-accuracy 3D machine visionmetrology using off-the-shelf TV cameras and lenses " in IEEE Journal of Robotics andAutomation (IEEE robot and robotization magazine) (1987) (a kind of adopt the stock camera and aspect high precision 3D machine vision metrology, use general camera calibration technology) proposed a kind of structural light three-dimensional measure in the method for second portion, mainly be earlier projector and camera to be demarcated, determine the position of projector and camera focus, calculate the three-dimensional information of target object again according to the relation of triangulation.This method need be measured the world coordinates of atypical characteristic point at the timing signal of projector; Need manufacturer that actual range between adjacent two pixels with camera of projector (horizontal and vertical) is provided; All will consider the focal length of projector and camera at the timing signal of projector and camera, and the step of calculating is many; After preliminary work is all finished, draw in the calculating of world coordinates of its corresponding object point more numerous and diverse by the pixel coordinate of certain point on the photograph (being positioned at the point on the grating), to obtain the world coordinates of this point earlier by a matrix multiplication, find the solution the straight-line equation that this point and camera are determined again, the plane equation that last ready prepd projector of simultaneous and grating are determined, form a ternary linear function group, separate the world coordinates that this system of equations can obtain object point.

Summary of the invention

The present invention be directed to above-mentioned the deficiencies in the prior art, a kind of structured light three-dimensional detection method based on homography matrix has been proposed, make on the determining of its relative position that homography matrix is applied to definite projector, camera and target object, only can obtain the world coordinates of object point by a matrix multiplication by the pixel coordinate of certain point on the photograph (being positioned at the point on the grating), the present invention has simplified the operation of three-dimensional detection under the condition that guarantees precision.

The present invention is achieved through the following technical solutions, the present invention includes following steps:

Step 1 is provided with two plane P parallel to each other between projector and video camera ₁And P ₂, two plane P ₁And P ₂In following step, be used to place gridiron pattern pattern, projector and the plane P of obtaining homography matrix ₂Between be provided with the projecting plane that has grating, a grating on projector and the projecting plane is determined an optical plane;

Step 2, utilize unique point in the gridiron pattern pattern obtain the camera imaging face respectively with plane P ₁And P ₂Corresponding homography matrix H _CQ1And H _CQ2, specific as follows:

At first, the gridiron pattern pattern is placed in plane P respectively ₁And P ₂On, take pictures with camera then, obtain two width of cloth images respectively;

Then, measure the relative position of the unique point in the cross-hatch pattern picture, get the initial point of one of them unique point as world coordinate system, other characteristic point coordinates have also just been determined, have been measured plane P simultaneously ₁And P ₂Between distance, i.e. the distance of unique point on the Z direction;

At last, according to the pixel coordinate of the unique point in the cross-hatch pattern picture, obtain the camera imaging face respectively with plane P ₁And P ₂Corresponding homography matrix H _CQ1And H _CQ2, homography matrix makes plane P ₁Or P ₂Go up any one point (x, y) on camera the coordinate of imaging (X, Y) satisfy following relation:

$\left(\begin{array}{c}x\\ y\\ 1\end{array}\right)=\left(\begin{array}{ccc}{h}_{11}& h_{12}& h_{13}\\ h_{21}& h_{22}& h_{23}\\ h_{31}& h_{32}& h_{33}\end{array}\right)\left(\begin{array}{c}X\\ Y\\ 1\end{array}\right)---\left(1\right)$

Wherein, (X Y) is the pixel coordinate of unique point in the imaging surface, and (x y) is plane P ₁Or P ₂The world coordinates of middle unique point.

Described the gridiron pattern pattern is placed in plane P respectively ₁And P ₂On, be specially: the gridiron pattern pattern is identical with coordinate on the Y direction at X in the unique point on two planes, realizes getting the initial point of one of them unique point as world coordinate system, just can determine other characteristic point coordinates simultaneously, to be convenient for measuring.

Step 3 utilizes unique point in the gridiron pattern pattern in plane P ₁And P ₂On measure the homography matrix H of projector projecting plane and camera imaging face correspondence respectively _PC1And H _PC2, specific as follows:

At first, the cross-hatch pattern picture is projected to plane P respectively ₁And P ₂On, take pictures by camera, obtain two width of cloth images respectively;

Then, measure projection cross-hatch pattern picture and two width of cloth images that photograph on the pixel coordinate of tessellated unique point;

At last, the homography matrix of same form in employing and the step 2 obtains in plane P ₁And P ₂The homography matrix H of last projector projecting plane and camera imaging face correspondence _PC1And H _PC2

Step 4, the straight-line equation of certain bar grating on the given projecting plane is according to the homography matrix H in the step 3 _PC1, matrix H _PC2Obtain straight line C ₁₁C ₁₂With straight line C ₂₁C ₂₂, by straight line C ₁₁C ₁₂And C ₂₁C ₂₂Obtain imaging surface C ₁₁C ₁₂C ₂₂C ₂₁

Step 5, the straight line C that tries to achieve according to step 4 ₁₁C ₁₂, straight line C ₂₁C ₂₂With the homography matrix H in the step 2 _CQ1, matrix H _CQ2Obtain straight line Q ₁₁Q ₁₂With straight line Q ₂₁Q ₂₂, by straight line Q ₁₁Q ₁₂And Q ₂₁Q ₂₂Determine the plane Q under the world coordinate system ₁₁Q ₁₂Q ₂₂Q ₂₁, plane Q ₁₁Q ₁₂Q ₂₂Q ₂₁Be on three-dimensional plane;

Step 6 is created as image planes C ₁₁C ₁₂C ₂₂C ₂₁With world coordinate system lower plane Q ₁₁Q ₁₂Q ₂₂Q ₂₁Between relation: (X, Y, 1) ^T=R (X _w, Y _w, Z _w) ^T+ T, wherein, (X Y) is imaging surface C ₁₁C ₁₂C ₂₂C ₂₁In coordinate, (X _w, Y _w, Z _w) be world coordinate system lower plane Q ₁₁Q ₁₂Q ₂₂Q ₂₁In coordinate, R is a rotation matrix, T is a translation vector, then the formula in the step 2 (1) is transformed to:

$\left(\begin{array}{c}x\\ y\\ 1\end{array}\right)=\left(\begin{array}{ccc}{h}_{11}& h_{12}& h_{13}\\ h_{21}& h_{22}& h_{23}\\ h_{31}& h_{32}& h_{33}\end{array}\right)\left(\begin{array}{cccc}{r}_{11}& r_{12}& r_{13}& T_x\\ r_{21}& r_{22}& r_{23}& T_y\\ r_{31}& r_{32}& r_{33}& T_z\end{array}\right)\left(\begin{array}{c}{X}_w\\ Y_w\\ Z_w\\ 1\end{array}\right)=\left(\begin{array}{cccc}{H}_{11}& H_{12}& H_{13}& H_{14}\\ H_{21}& H_{22}& H_{23}& H_{24}\\ H_{31}& H_{32}& H_{33}& H_{34}\end{array}\right)\left(\begin{array}{c}{X}_w\\ Y_w\\ Z_w\\ 1\end{array}\right)---\left(2\right)$

As seen 3 * 4 matrix tables in the formula (2) illustrate the transformation relation of two faces.Utilize two enough characteristic of correspondence points of face epipodium can try to achieve this 3 * 4 matrix.

Step 7 is placed on plane P to target object ₂On, projecting structural optical is taken the set of diagrams picture that obtains containing structured light, then structured light is decoded, and distinguishes the number of grating, and obtaining grating is having the position on the camera imaging face under the target object influence;

Step 8, obtaining grating in step 7 is having under the object influence on the basis of the position on the camera imaging face, acquires the plane C that every grating is determined separately ₁₁C ₁₂C ₂₂C ₂₁And Q ₁₁Q ₁₂Q ₂₂Q ₂₁, and by plane C ₁₁C ₁₂C ₂₂C ₂₁(camera imaging areal coordinate system) is to plane Q ₁₁Q ₁₂Q ₂₂Q ₂₁3 * 4 matrixes of (world coordinate system) mapping obtain every grating position under world coordinate system by the transformation relation in the step 6, thereby obtain three-dimensional information.

Among the present invention, the plane Q that optical plane that projector and certain bar grating are determined and above-mentioned steps five obtain ₁₁Q ₁₂Q ₂₂Q ₂₁Overlap fully, utilize this characteristic, obtained plane Q ₁₁Q ₁₂Q ₂₂Q ₂₁Just obtained the optical plane that projector and certain bar grating are determined, wherein plane P ₂Be the objective plane that will put article, plane P ₁And P ₂Parallel, straight line Q ₁₁Q ₁₂It is plane P ₁With the intersection of optical plane, straight line Q ₂₁Q ₂₂It is plane P ₂Intersection with optical plane.Straight line Q ₁₁Q ₁₂Imaging on camera is straight line C ₁₁C ₁₂, straight line Q ₂₁Q ₂₂Imaging on camera is straight line C ₂₁C ₂₂If plane Q ₁₁Q ₁₂Q ₂₂Q ₂₁On camber line be that optical grating projection forms on certain article, then the imaging of this camber line on camera must be plane C ₁₁C ₁₂C ₂₂C ₂₁On certain bar camber line.Exist one 3 * 4 matrix to make plane C as can be known by foregoing description ₁₁C ₁₂C ₂₂C ₂₁And Q ₁₁Q ₁₂Q ₂₂Q ₂₁On point corresponding one by one, this matrix must make on two planes that the point on two camber lines is corresponding one by one so.That is to say, when this 3 * 4 matrixes are known, specify on the empty camber line a bit (pixel coordinate), just can obtain a bit (world coordinates) on the corresponding real camber line, this has just reached the purpose of three-dimensional measurement.

Compared with prior art, the present invention has following beneficial effect:

1, the measurement world coordinates that the present invention can be easy, art methods need be measured the world coordinates of atypical characteristic point at the timing signal of projector, and the inventive method is as long as measure the world coordinates of regular unique point, for example the unique point of Shi Yonging is 7 * 5=35, art methods need be measured 35 unique points, and after the inventive method only need measure 2, calculate the unique point that obtains other again;

2, the present invention does not need manufacturer that actual range between adjacent two pixels with camera of projector (horizontal and vertical) is provided, and method promptly of the prior art is device-dependent, and the inventive method has been avoided the device dependency problem on the one hand at this;

3, the present invention has omitted numerous and diverse calculating process of projector and camera focus, thereby has also avoided the device dependency problem on the one hand at this;

4, it is more convenient to obtain the world coordinates of its corresponding object point by the pixel coordinate of certain point on the photograph (being positioned at the point on the grating) among the present invention, only can obtain the world coordinates of object point by a matrix multiplication, and art methods will obtain the world coordinates of this point earlier by a matrix multiplication, find the solution the straight-line equation that this point and camera are determined again, the plane equation that last ready prepd projector of simultaneous and grating are determined, form a ternary linear function group, separate the world coordinates that this system of equations can obtain object point.

Description of drawings

Fig. 1 is a principle of work synoptic diagram of the present invention.

Fig. 2 is the real gridiron pattern that the present invention uses;

Among the figure, (a) be camera photograph at P ₁Real gridiron pattern on the plane, (b) be camera photograph at P ₂Real gridiron pattern on the plane.

Fig. 3 is the gridiron pattern of projection among the present invention;

Among the figure, (a) be camera photograph at P ₁Projection gridiron pattern on the plane, (b) be camera photograph at P ₂Projection gridiron pattern on the plane.

Fig. 4 is the image of target object under structured light among the present invention;

Among the figure, (a) be camera photograph at P ₂The object under the first frame structure influence of light on the plane, (b) be camera photograph at P ₂The object under the second frame structure influence of light on the plane, (c) be camera photograph at P ₂The object under the 3rd frame structure influence of light on the plane, (d) be camera photograph at P ₂The object under the 4th frame structure influence of light on the plane, (e) be camera photograph at P ₂The object under the 5th frame structure influence of light on the plane, (f) be camera photograph at P ₂The object under the 6th frame structure influence of light on the plane, (g) be camera photograph at P ₂The object under the 7th frame structure influence of light on the plane.

Fig. 5 is the three-D profile of target object among the present invention;

Among the figure, (a) being the three-D profile of target object under certain angle, (b) is the three-D profile of target object under another angle.

Embodiment

Below in conjunction with accompanying drawing embodiments of the invention are elaborated: present embodiment is being to implement under the prerequisite with the technical solution of the present invention, provided detailed embodiment and concrete operating process, but protection scope of the present invention is not limited to following embodiment.

As shown in Figure 1, present embodiment comprises the steps:

Step 1 is provided with two plane P parallel to each other between projector and video camera ₁And P ₂, two plane P ₁And P ₂In following step, be used to place gridiron pattern pattern, projector and the plane P of obtaining homography matrix ₂Between be provided with the projecting plane that has grating, a grating on projector and the projecting plane is determined an optical plane;

Step 2, utilize unique point in the gridiron pattern pattern obtain the camera imaging face respectively with plane P ₁And P ₂Corresponding homography matrix H _CQ1And H _CQ2, specific as follows:

At first, the gridiron pattern pattern is placed in plane P respectively ₁And P ₂On, take pictures with camera then, obtain two width of cloth images respectively, as shown in Figure 2;

Then, measure the relative position of the unique point in the cross-hatch pattern picture, get the initial point of one of them unique point as world coordinate system, other characteristic point coordinates have also just been determined, have been measured plane P simultaneously ₁And P ₂Between distance, i.e. the distance of unique point on the Z direction;

At last, according to the pixel coordinate of the unique point in the cross-hatch pattern picture, obtain the camera imaging face respectively with plane P ₁And P ₂Corresponding homography matrix H _CQ1And H _CQ2, homography matrix makes plane P ₁Or P ₂Go up any one point (x, y) on camera the coordinate of imaging (X, Y) satisfy following relation:

$\left(\begin{array}{c}x\\ y\\ 1\end{array}\right)=\left(\begin{array}{ccc}{h}_{11}& h_{12}& h_{13}\\ h_{21}& h_{22}& h_{23}\\ h_{31}& h_{32}& h_{33}\end{array}\right)\left(\begin{array}{c}X\\ Y\\ 1\end{array}\right)---\left(1\right)$

Wherein, (X Y) is the pixel coordinate of unique point in the imaging surface, and (x y) is plane P ₁Or P ₂The world coordinates of middle unique point.

Described the gridiron pattern pattern is placed in plane P respectively ₁And P ₂On, be specially: the gridiron pattern pattern is identical with coordinate on the Y direction at X in the unique point on two planes, realizes getting the initial point of one of them unique point as world coordinate system, just can determine other characteristic point coordinates simultaneously, to be convenient for measuring.

Step 3 utilizes unique point in the gridiron pattern pattern in plane P ₁And P ₂On measure the homography matrix H of projector projecting plane and camera imaging face correspondence respectively _PC1And H _PC2, specific as follows:

At first, the cross-hatch pattern picture is projected to plane P respectively ₁And P ₂On, take pictures by camera, obtain two width of cloth images respectively, as shown in Figure 3;

Then, the pixel coordinate of the tessellated unique point on two width of cloth images of measuring projection cross-hatch pattern picture and photographing, the pixel coordinate of the tessellated unique point on projection cross-hatch pattern picture and two width of cloth images that photograph all can be than being easier to record (can record automatically by computer, also can manually utilize the image software of Photoshop and so on to find out);

At last, the homography matrix of same form in employing and the step 2 obtains in plane P ₁And P ₂The homography matrix H of last projector projecting plane and camera imaging face correspondence _PC1And H _PC2

Step 4, the straight-line equation of certain bar grating on the given projecting plane is according to the homography matrix H in the step 3 _PC1, matrix H _PC2Obtain straight line C ₁₁C ₁₂With straight line C ₂₁C ₂₂, by straight line C ₁₁C ₁₂And C ₂₁C ₂₂Obtain imaging surface C ₁₁C ₁₂C ₂₂C ₂₁

Step 5, the straight line C that tries to achieve according to step 4 ₁₁C ₁₂, straight line C ₂₁C ₂₂With the homography matrix H in the step 2 _CQ1, matrix H _CQ2Obtain straight line Q ₁₁Q ₁₂With straight line Q ₂₁Q ₂₂, by straight line Q ₁₁Q ₁₂And Q ₂₁Q ₂₂Determine the plane Q under the world coordinate system ₁₁Q ₁₂Q ₂₂Q ₂₁, plane Q ₁₁Q ₁₂Q ₂₂Q ₂₁Be on three-dimensional plane;

Step 6 is created as image planes C ₁₁C ₁₂C ₂₂C ₂₁With world coordinate system lower plane Q ₁₁Q ₁₂Q ₂₂Q ₂₁Between relation: (X, Y, 1) ^T=R (X _w, Y _w, Z _w) ^T+ T, wherein, (X Y) is imaging surface C ₁₁C ₁₂C ₂₂C ₂₁In coordinate, (X _w, Y _w, Z _w) be world coordinate system lower plane Q ₁₁Q ₁₂Q ₂₂Q ₂₁In coordinate, R is a rotation matrix, T is a translation vector, then the formula in the step 2 (1) is transformed to:

$\left(\begin{array}{c}x\\ y\\ 1\end{array}\right)=\left(\begin{array}{ccc}{h}_{11}& h_{12}& h_{13}\\ h_{21}& h_{22}& h_{23}\\ h_{31}& h_{32}& h_{33}\end{array}\right)\left(\begin{array}{cccc}{r}_{11}& r_{12}& r_{13}& T_x\\ r_{21}& r_{22}& r_{23}& T_y\\ r_{31}& r_{32}& r_{33}& T_z\end{array}\right)\left(\begin{array}{c}{X}_w\\ Y_w\\ Z_w\\ 1\end{array}\right)=\left(\begin{array}{cccc}{H}_{11}& H_{12}& H_{13}& H_{14}\\ H_{21}& H_{22}& H_{23}& H_{24}\\ H_{31}& H_{32}& H_{33}& H_{34}\end{array}\right)\left(\begin{array}{c}{X}_w\\ Y_w\\ Z_w\\ 1\end{array}\right)---\left(2\right)$

As seen 3 * 4 matrix tables in the formula (2) illustrate the transformation relation of two faces.Utilize two enough characteristic of correspondence points of face epipodium can try to achieve this 3 * 4 matrix.

Step 7 is placed on plane P to target object ₂On, projecting structural optical is taken the set of diagrams picture (as shown in Figure 4) that obtains containing structured light, then structured light is decoded, and distinguishes the number of grating, has 2 in the present embodiment ⁷The bar grating, obtaining grating is having the position on the camera imaging face under the target object influence;

Described structured light is decoded, be specially: the binary number of setting corresponding figure place according to the number of image, zone, arbitrfary point in the image is provided with corresponding binary digit, which grating is this numeral it belong to, such as: Fig. 4 (a) is two width of cloth figure (b), first width of cloth figure has only two zones black and white, second width of cloth figure has four black and white zones, can and distinguish this 4 zones with two binary number representation---(00,01,10,11), 0 expression black, 1 expression white, first bit representation, first width of cloth figure, second bit representation, second width of cloth figure (1 first of area 0 is that 0 this zone of expression is a black in first width of cloth figure, and second is that 1 this zone of expression is white in second width of cloth figure).Have 7 width of cloth figure among Fig. 4, so, 7 binary number then will be selected for use.

Step 8, obtaining grating in step 7 is having under the object influence on the basis of the position on the camera imaging face, acquires the plane C that every grating is determined separately ₁₁C ₁₂C ₂₂C ₂₁And Q ₁₁Q ₁₂Q ₂₂Q ₂₁, and by plane C ₁₁C ₁₂C ₂₂C ₂₁(camera imaging areal coordinate system) is to plane Q ₁₁Q ₁₂Q ₂₂Q ₂₁3 * 4 matrixes of (world coordinate system) mapping obtain every grating position under world coordinate system by the transformation relation in the step 6, thereby obtain three-dimensional information.

As shown in Figure 5, be to see in the past effect from two angles respectively, a white line is exactly a grating, and the white line that is formed by all gratings just can construct the three-D profile of target object.

The present embodiment method can be easy the measurement world coordinates, and avoided the device dependency problem, under the condition that guarantees precision, simplified the operation of three-dimensional detection.

Claims (4)

1, a kind of structured light three-dimensional detection method based on homography matrix is characterized in that, comprises the steps:

Step 1 is provided with two plane P parallel to each other between projector and video camera ₁And P ₂, two plane P ₁And P ₂Be used to place gridiron pattern pattern, projector and the plane P of obtaining homography matrix ₁Between be provided with the projecting plane that has grating, a grating on projector and the projecting plane is determined an optical plane;

Step 2, utilize unique point in the gridiron pattern pattern obtain the camera imaging face respectively with plane P ₁And P ₂Corresponding homography matrix H _CQ1And H _CQ2

Step 3 utilizes unique point in the gridiron pattern pattern in plane P ₁And P ₂On measure the homography matrix H of projector projecting plane and camera imaging face correspondence respectively _PC1And H _PC2

Step 4, the straight-line equation of certain bar grating on the given projecting plane is according to the homography matrix H in the step 3 _PC1, matrix H _PC2Obtain straight line C ₁₁C ₁₂With straight line C ₂₁C ₂₂, by straight line C ₁₁C ₁₂And C ₂₁C ₂₂Be specified to image planes C ₁₁C ₁₂C ₂₂C ₂₁

Step 5, the straight line C that tries to achieve according to step 4 ₁₁C ₁₂, straight line C ₂₁C ₂₂With the homography matrix H in the step 2 _CQ1, matrix H _CQ2Obtain straight line Q ₁₁Q ₁₂With straight line Q ₂₁Q ₂₂, by straight line Q ₁₁Q ₁₂And Q ₂₁Q ₂₂Determine the plane Q under the world coordinate system ₁₁Q ₁₂Q ₂₂Q ₂₁, plane Q ₁₁Q ₁₂Q ₂₂Q ₂₁Be on three-dimensional plane;

Step 6 is created as image planes C ₁₁C ₁₂C ₂₂C ₂₁With world coordinate system lower plane Q ₁₁Q ₁₂Q ₂₂Q ₂₁Between relation: (X, Y, 1) ^T=R (X _w, Y _w, Z _w) ^T+ T, wherein, (X Y) is imaging surface C ₁₁C ₁₂C ₂₂C ₂₁In coordinate, (X _w, Y _w, Z _w) be world coordinate system lower plane Q ₁₁Q ₁₂Q ₂₂Q ₂₁In coordinate, R is a rotation matrix, T is translation vector, then plane P ₁Or P ₂Go up any one point (x, y) with the world coordinate system lower plane on corresponding point (X _w, Y _w, Z _w) relation as follows:

$\left(\begin{array}{c}x\\ y\\ 1\end{array}\right)=\left(\begin{array}{ccc}{h}_{11}& h_{12}& h_{13}\\ h_{21}& h_{22}& h_{23}\\ h_{31}& h_{32}& h_{33}\end{array}\right)\left(\begin{array}{cccc}{r}_{11}& r_{12}& r_{13}& T_x\\ r_{21}& r_{22}& r_{23}& T_y\\ r_{31}& r_{32}& r_{33}& T_z\end{array}\right)\left(\begin{array}{c}{X}_w\\ Y_w\\ Z_w\\ 1\end{array}\right)=\left(\begin{array}{cccc}{H}_{11}& H_{12}& H_{13}& H_{14}\\ H_{21}& H_{22}& H_{23}& H_{24}\\ H_{31}& H_{32}& H_{33}& H_{34}\end{array}\right)\left(\begin{array}{c}{X}_w\\ Y_w\\ Z_w\\ 1\end{array}\right)$

In the formula, 3 * 4 matrix tables illustrate the transformation relation of two faces, utilize on imaging surface and the world coordinate system lower plane characteristic of correspondence point can determine this 3 * 4 matrix;

Step 7 is placed on plane P to target object ₂On, projecting structural optical is taken the set of diagrams picture that obtains containing structured light, then structured light is decoded, and distinguishes the number of grating, and obtaining grating is having the position on the camera imaging face under the target object influence;

Step 8, obtaining grating in step 7 is having under the object influence, on the basis of the position on the camera imaging face, acquires the plane C that every grating is determined separately ₁₁C ₁₂C ₂₂C ₂₁And Q ₁₁Q ₁₂Q ₂₂Q ₂₁, and by plane C ₁₁C ₁₂C ₂₂C ₂₁To plane Q ₁₁Q ₁₂Q ₂₂Q ₂₁3 * 4 matrixes of mapping obtain every grating position under world coordinate system by the transformation relation in the step 6, thereby obtain three-dimensional information.

2, the structured light three-dimensional detection method based on homography matrix according to claim 1 is characterized in that, described utilize unique point in the gridiron pattern pattern obtain the camera imaging face respectively with plane P ₁And P ₂Corresponding homography matrix H _CQ1And H _CQ2, specific as follows:

At first, the gridiron pattern pattern is placed in plane P respectively ₁And P ₂On, take pictures with camera then, obtain two width of cloth images respectively;

Then, measure the relative position of the unique point in the cross-hatch pattern picture, get the initial point of one of them unique point as world coordinate system, other characteristic point coordinates have also just been determined, have been measured plane P simultaneously ₁And P ₂Between distance, i.e. the distance of unique point on the Z direction;

At last, according to the pixel coordinate of the unique point in the cross-hatch pattern picture, obtain the camera imaging face respectively with plane P ₁And P ₂Corresponding homography matrix H _CQ1And H _CQ2, homography matrix makes plane P ₁Or P ₂Go up any one point (x, y) on camera the coordinate of imaging (X, Y) satisfy following relation:

$\left(\begin{array}{c}x\\ y\\ 1\end{array}\right)=\left(\begin{array}{ccc}{h}_{11}& h_{12}& h_{13}\\ h_{21}& h_{22}& h_{23}\\ h_{31}& h_{32}& h_{33}\end{array}\right)\left(\begin{array}{c}X\\ Y\\ 1\end{array}\right)$

Wherein, (X Y) is the pixel coordinate of unique point in the imaging surface, and (x y) is plane P ₁Or P ₂The world coordinates of middle unique point.

3, the structured light three-dimensional detection method based on homography matrix according to claim 1 is characterized in that, describedly utilizes unique point in the gridiron pattern pattern in plane P ₁And P ₂On measure the homography matrix H of projector projecting plane and camera imaging face correspondence respectively _PC1And H _PC2, specific as follows:

At first, the cross-hatch pattern picture is projected to plane P respectively ₁And P ₂On, take pictures by camera, obtain two width of cloth images respectively;

Then, measure projection cross-hatch pattern picture and two width of cloth images that photograph on the pixel coordinate of tessellated unique point;

At last, the homography matrix of same form in employing and the step 2 obtains in plane P ₁And P ₂The homography matrix H of last projector projecting plane and camera imaging face correspondence _PC1And H _PC2

4, according to claim 2 or 3 described structured light three-dimensional detection methods, it is characterized in that, described the gridiron pattern pattern is placed in plane P respectively based on homography matrix ₁And P ₂On, be specially: the gridiron pattern pattern is identical with coordinate on the Y direction at X in the unique point on two planes, to realize getting the initial point of one of them unique point as world coordinate system, just can determine other characteristic point coordinates simultaneously.

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