CN115183748A - Overwater and underwater point cloud consistency evaluation method based on multi-target three-dimensional connection - Google Patents
Overwater and underwater point cloud consistency evaluation method based on multi-target three-dimensional connection Download PDFInfo
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Abstract
The invention discloses a method for evaluating consistency of point cloud on water and underwater based on multi-target three-dimensional connection, which belongs to the technical field of measuring azimuth and is used for evaluating consistency of point cloud data, and the method comprises the following steps: respectively acquiring an overwater part of laser point cloud and an underwater part of multi-beam point cloud of the device by using an overwater and underwater integrated measuring system, and acquiring a measured value of a central coordinate of an underwater target under water in an ENU system by using a radius constraint-based spherical fitting algorithm; calculating a conversion parameter between an ENU system and a DEV system by using a design value and a measurement value of a central coordinate of the overwater target and a space coordinate conversion model of any angle; calculating a reference value of the underwater target center coordinate under the ENU system by using the design value of the underwater target center coordinate and the conversion parameter from the DEV system to the ENU system; and comparing the reference value and the measured value of the underwater target central coordinate in the ENU system, and calculating the difference and the error of the underwater target central coordinate component in the east-north-sky direction.
Description
Technical Field
The invention discloses an overwater and underwater point cloud consistency assessment method based on multi-target three-dimensional connection, and belongs to the technical field of azimuth measurement.
Background
During the operation of the shipborne overwater and underwater integrated measurement system, due to the limitation of factors such as the working performance of the sensor, the installation position of the sensor, the draught of the ship, the tide and the topography of the underwater, the overwater point cloud and the underwater point cloud inevitably have certain gaps and malpositions, so people need to accurately evaluate the splicing seam size of the overwater and underwater point clouds and evaluate the malposition condition of the overwater and underwater point clouds, and the two aspects are collectively called as the consistency of the overwater and underwater point clouds. The consistency of the point cloud marks the measurement precision of the underwater and overwater integrated measurement system. At present, a method for evaluating splicing seams of point clouds mainly depends on a method for measuring markers manually, a large number of uniform overwater point cloud groups and underwater point cloud groups which are easy to distinguish are selected from different areas, and gap distances are measured manually by using point cloud visualization software. The method for manually measuring the marker mainly adopts a manual interaction mode, point cloud visualization software is used for selecting the size and the position relation of the marker manually-measured splicing seam on the shore or in water, manually-selected characteristic points have high randomness, and the consistency of repeated measurement is difficult to guarantee. Filtering and thinning in the data post-processing process may cause some missing of feature points, so that the measurement result is biased.
Disclosure of Invention
The invention discloses a method for evaluating consistency of point clouds above and below water based on multi-target three-dimensional connection, which aims to solve the problems of high randomness and low precision caused by manually measuring markers to evaluate the consistency of point cloud data in the prior art.
An overwater and underwater point cloud consistency assessment method based on multi-target three-dimensional connection comprises the following steps:
s1: manufacturing a three-dimensional target device;
s2: collecting overwater and underwater point cloud data of the three-dimensional target device;
s3: evaluating the consistency of the cloud point above water and under water;
s3.1, calculating the measurement coordinate of the target center in the device under an ENU system based on a spherical fitting algorithm of radius constraint;
s3.2, calculating conversion parameters from the device system to the ENU system based on the space coordinate conversion model of any angle and the coordinates of the ENU system and the center of the underwater target of the device system;
s3.3, calculating a reference value of the central coordinate of the underwater target under the ENU system based on the conversion parameters and the coordinate of the central coordinate of the underwater target under the ENU system
And S3.4, calculating the difference and the mean error of the underwater point cloud in the east-north-sky direction based on the reference value and the measured value of the underwater target central coordinate under the ENU system, and evaluating the consistency of the data of the underwater point cloud on the water.
Preferably, the manufacturing requirements of the stereoscopic target device in step S1 are:
the three-dimensional target device comprises a target and a connecting piece, wherein a space polyhedron is formed by more than 5 rigidly connected targets, the target is in a regular shape, the center of the target can be defined as a mass center, a centroid or other persons as a designated position, and the size of the target needs to consider the measurement resolution of different shipborne water and underwater integrated systems;
the connecting piece is used for supporting and fixing the targets, and rigid connection between the targets is guaranteed.
The spatial structure of the three-dimensional target device ensures that the target is not or less shielded by the connecting piece, and the target can form a plurality of planes with different orientations for consistency evaluation;
the three-dimensional target device needs to measure the spatial relative position relation of each target, a three-dimensional target device system is defined, parameters in machining design are directly used under the condition that the target position precision requirement is not high, and a total station, an industrial measurement system or a three-dimensional laser scanner is used for calibrating the spatial position of each target ball in the three-dimensional target device under the condition that the precision requirement is high;
preferably, the acquiring point cloud data of the stereoscopic target device in step S2 includes:
the three-dimensional target device is placed in water, the part above the water surface is required to be ensured to have planes which are not less than 4 targets and are formed in different directions, and the part under the water is not less than 1 target.
The three-dimensional target device is simultaneously scanned by the overwater laser radar and the underwater multi-beam in the shipborne overwater and underwater integrated measuring system, so that the targets above the water surface are scanned by the laser radar, and the targets below the water surface are scanned by the multi-beam.
Preferably, step S3.1 comprises:
and (3) extracting the target in the point cloud from the data scanned in the step (S2) in a manual or automatic mode, and calculating to obtain the approximate coordinate of the center of the target in a least square mode.
The spherical equation of space is:
(x i -x) 2 +(y i -y) 2 +(z i -z) 2 ＝r 2 (1.1)
wherein, (x, y, z), r are the sphere center coordinate and radius respectively. (x) i ,y i ,z i ) Are spherical point coordinates.
Expanding and transposing the formula (1.1) can obtain:
the following are not to be recorded:
wherein (x) 1 ,y 1 ,z 1 ),(x 2 ,y 2 ,z 2 ),…,(x n ,y n ,z n ) Respectively the coordinates of n spherical points.
Solving the over-determined equation as follows, and recording the solution as approximate value (x) of the sphere center of the target 0 ,y 0 ,z 0 ) And approximate radius r of the target 0 。
X＝(B T B) -1 B T Y (1.3)
Preferably, step S3.1 comprises:
and (4) calculating the measurement coordinates of the target center in the device under the ENU system by using a spherical fitting algorithm based on radius constraint and the approximate coordinate values of the target center acquired in the step 4.
The following function is constructed:
to (1.4) formula in (x) 0 ,y 0 ,z 0 ,r 0 ) The process linearization yields:
spherical radius constraint equation:
r d +V r ＝r 0 +δr＝r (1.6)
in the formula
i represents the number of spherical points;
V d design value r for target d The number of corrections of (a);
r d is a design value of the target sphere radius;
[δx δy δz δr] T ＝[(x-x 0 )(y-y 0 )(z-z 0 )(r-r 0 )] T ；
l =0 as observed value;
v is the correction number of the observed value;
simultaneous (1.5) and (1.6) formulas are written in matrix form:
in the formula (I), the compound is shown in the specification,
solving equation (1.7) using the indirect adjustment method, the following matrix is defined:
wherein the weight matrix P is a weight matrix I represented by the formula (1.5) n×n Weight matrix P of constraint conditional equation (1.6) c Composition = 10.
Obtained parameter x 0 ,y 0 ,z 0 ,r 0 Correction numbers δ x, δ y, δ z, δ r:
[δx δy δz δr] T ＝(B T PB) -1 B T Pl (1.8)
and 4, taking the approximate coordinates of the target sphere center and the radius calculated in the step 4 as iteration initial values. Delta r<ε r (design value r) 0 Error of (e) r ) Is an abort condition for the iteration. The requirements can be met through 2-3 iterations.
The adjustment result is thus:
the measured values of the coordinates of the n targets in the device under the earth-centered earth-fixed system are recorded as
Defining one target as the device's northeast Earth (ENU) geographic system (system g) origin Q, and the other m targets have the following coordinates in ENU with Q as origin:
preferably, step S3.2 comprises:
calculating conversion parameters from the ENU system to the device system (DEV system) based on an arbitrary angle space coordinate conversion model and coordinates of an overwater target under the ENU system and the device system, wherein a rotation matrix of the conversion parameters is expressed as
The translation vector of the coordinate system is
Preferably, step S3.3 comprises:
calculating the reference value of the coordinates of the underwater target in the ENU system by using the transformation parameters acquired in the step S.2 and the coordinates of the n underwater targets in the DEV system
Preferably, step S3.4 comprises:
reference value based on n underwater target coordinates under ENU system
And measured value
Calculating the difference value delta = [ delta ] of the underwater point cloud in the east-north-sky direction E δ N δ U ] T And sum error σ = [ σ ] E σ N σ U ] T And evaluating the consistency of the cloud point data on the water and the underwater point. Note the book
If the stereo target device is observed repeatedly m times, the difference value and the error in the east-north-sky direction of the ith time are respectively recorded as: delta i And σ i . The reproducibility of the stereoscopic target device was obtained from (4.2):
the invention has the following advantages: compared with the prior art, the method uses the target to replace a natural feature, ensures the consistency of feature selection in multiple measurements, uses a target fitting method to calculate the target coordinate to replace the traditional method of manually selecting point cloud angular points, and ensures the consistency of the results of evaluating the dislocation and gap of the point clouds above and below water; the three-dimensional target device is used for fixing the relative position relation among a plurality of targets to form a measurable device system, the conversion relation between the device system and the geocentric earth-fixed system can be accurately obtained through measuring the targets of the reference part, and the difference between the measured value and the theoretical value of the underwater target is obtained.
Drawings
FIG. 1 is a technical flow diagram of the present invention;
FIG. 2 is a block diagram of a three-dimensional target device of the present invention;
the reference numerals include: 1-connecting piece, 2-water target and 3-underwater target.
Detailed Description
The invention is described in further detail below with reference to the following figures and detailed description:
the terms of several technologies related to the present invention explain:
point cloud data: the point cloud data comprises information such as space three-dimensional coordinates and reflection intensity.
Multi-beam point cloud data: the system is used for acquiring point cloud data of the submarine topographic surface by using a multi-beam sounding system.
Laser point cloud data: refers to point cloud data of the surface of a ground feature collected using a laser scanner.
Shipborne overwater and underwater integrated measurement system: the method is used for integrated measurement from the submarine topography to the coastal terrain under the same measurement reference through the integration of devices such as a multi-beam depth sounder, a laser scanner, a marine vessel positioning navigation and the like.
An assessment method for consistency of cloud point cloud above and below water based on multi-target stereo connection is disclosed as fig. 1, and comprises the following steps:
s1: manufacturing a three-dimensional target device;
s2: collecting overwater and underwater point cloud data of the three-dimensional target device;
s3: evaluating the consistency of the cloud points above and below water;
s3.1, calculating the measurement coordinate of the target center in the device under an ENU system based on a spherical fitting algorithm of radius constraint;
s3.2, calculating conversion parameters from the device system to the ENU system based on the space coordinate conversion model of any angle and the coordinates of the ENU system and the underwater target center of the device system;
s3.3 calculating the reference value of the central coordinate of the underwater target in the ENU system based on the conversion parameters and the coordinate of the central coordinate of the underwater target in the device system
And S3.4, calculating the difference and the error of the underwater point cloud in the east-north-sky direction based on the reference value and the measured value of the underwater target central coordinate under the ENU system, and evaluating the consistency of the point cloud data above the water and underwater.
The technical scheme related to the invention is divided into 3 technical links for analysis:
the three-dimensional target device comprises a target and a connecting piece 1, wherein a space polyhedron is formed by more than 5 rigidly connected targets, the target is in a regular shape, the center of the target can be defined as a mass center, a centroid or other people as a specified position, and the size of the target needs to consider the measurement resolution of different shipborne water and underwater integrated systems;
the connecting piece 1 is used for supporting and fixing the targets, and rigid connection between the targets is guaranteed.
The spatial structure of the three-dimensional target device should ensure that the target is not or less shielded by the connecting piece 1, and the target should form a plurality of planes in different directions for consistency evaluation;
the three-dimensional target device needs to measure the spatial position relation of each target, a three-dimensional target device system is defined, parameters in machining design are directly used under the condition that the target position precision requirement is not high, and the spatial position of each target ball in the three-dimensional target device is calibrated by using a total station, an industrial measurement system or a three-dimensional laser scanner under the condition that the precision requirement is high;
according to the manufacturing requirements of the three-dimensional target device, a reference three-dimensional target device is provided, as shown in fig. 2, 6 targets of the underwater part are numbers 1-6, 4 targets of the water part are numbers 7-10, and the calibration results are shown in table 1.
TABLE 1 target coordinate under the three-dimensional target device system (sphere center)
| Serial number | Type (B) | X coordinate (m) | Y coordinate (m) | Z coordinate (m) |
| No. 1 target ball | Underwater target | 0.000 | 0.000 | 0.000 |
| No. 2 target ball | Underwater target | 2.165 | 1.250 | 0.000 |
| No. 3 target ball | Underwater target | 0.000 | 2.500 | 0.000 |
| No. 4 target ball | Underwater target | 0.000 | 0.000 | 2.990 |
| No. 5 target ball | Underwater target | 2.165 | 1.250 | 2.990 |
| No. 6 target ball | Underwater target | 0.000 | 2.500 | 2.990 |
| No. 7 target ball | Underwater target | 0.000 | 0.000 | 5.970 |
| No. 8 target ball | Underwater target | 2.165 | 1.250 | 5.970 |
| No. 9 target ball | Underwater target | 0.000 | 2.500 | 5.970 |
| No. 10 target ball | Water target | 1.083 | 2.165 | 8.135 |
And (2) collecting the overwater and underwater point cloud of the three-dimensional target device:
the three-dimensional target device is placed in water, the part above the water surface is required to be ensured to have planes which are not less than 3 targets and are formed in different directions, and the part under the water is not less than 1 target.
The method is characterized in that a water laser radar and an underwater multi-beam simultaneous scanning three-dimensional target device in a shipborne water and underwater integrated measuring system are used, the target above the water surface is scanned by the laser radar, and the target below the water surface is scanned by the multi-beam.
And 3, evaluating consistency of underwater point clouds on water:
and (3) calculating the measurement coordinate of the target center in the device under the ENU system by using the data obtained by scanning in the link 2 based on a spherical fitting algorithm of radius constraint.
First, approximate coordinates of the target in the geocentric earth fixation system are calculated.
The spherical equation of space is:
(x i -x) 2 +(y i -y) 2 +(z i -z) 2 ＝r 2 (1.1)
wherein, (x, y, z) and r are respectively a sphere center coordinate and a radius. (x) i ,y i ,z i ) Are spherical point coordinates.
Expanding and transposing the formula (1.1) can obtain:
the following are not to be recorded:
wherein (x) 1 ,y 1 ,z 1 ),(x 2 ,y 2 ,z 2 ),…,(x n ,y n ,z n ) Respectively the coordinates of n spherical points.
Solving the over-determined equation as follows, and recording the solution as approximate value (x) of the sphere center of the target 0 ,y 0 ,z 0 ) And approximate radius r of the target 0 。
X＝(B T B) -1 B T Y (1.3)
Secondly, calculating the measurement coordinate of the target center in the device under the geocentric geostationary system by using a spherical fitting algorithm based on radius constraint and the approximate coordinate value of the target center acquired in the previous step.
The following function is constructed:
to (1.4) formula in (x) 0 ,y 0 ,z 0 ,r 0 ) The process linearization yields:
spherical radius constraint equation:
r d +V r ＝r 0 +δr＝r (1.6)
in the formula
i represents the number of spherical points;
V d design value r for target d The number of corrections of (a);
r d is a design value of the target sphere radius;
[δx δy δz δr] T ＝[(x-x 0 )(y-y 0 )(z-z 0 )(r-r 0 )] T ；
l =0 as observed value;
v is the correction number of the observed value;
simultaneous (1.5) and (1.6) formulas are written in matrix form:
in the formula (I), the compound is shown in the specification,
solving equation (1.7) using the indirect adjustment method, the following matrix is defined:
wherein the weight matrix P is a weight matrix I represented by the formula (1.5) n×n Weight matrix P of constraint conditional equation (1.6) c =10 composition.
Obtained parameter x 0 ,y 0 ,z 0 ,r 0 Correction numbers δ x, δ y, δ z, δ r:
[δx δy δz δr] T ＝(B T PB) -1 B T Pl (1.8)
and 4, taking the approximate coordinates of the target sphere center and the radius calculated in the step 4 as iteration initial values. Delta r<ε r (design value r) 0 Error of (e) r ) Is an abort condition for the iteration. The requirements can be met through 2-3 iterations.
The adjustment result is thus:
the measured values of the coordinates of the n targets in the device under the earth-centered earth-fixed system are recorded as
Finally, the target is transformed from the ECEF coordinate system to the ENU coordinate system.
Defining one target as the device's northeast Earth (ENU) geographic system (system g) origin Q, and the other m targets have the following coordinates in ENU with Q as origin:
calculating geographic coordinates
And ECEF coordinates
λ is the geographic longitude,
for the geographical latitude, the formula for solving the geographical coordinate by the geocentric rectangular coordinate is as follows:
atan2 (x, y) is an arctangent value function for calculating given abscissa and ordinate points, and the value range is (-pi, pi)]，R e And e respectively representing ellipse semiaxis and ellipse eccentricity, and making iteration initial value t 0 =0, sufficient numerical calculation accuracy can be achieved after 5 to 6 iterations, and then t is calculated i+1 Tangent of inversion
The latitude can be obtained
Defining an underwater target 3 as the origin Q, lambda of the northeast Earth (ENU) geographic system (g system) of the device Q Is the geographic longitude of the point Q and,
for the geographic latitude of the Q point, the coordinate transformation matrix from the geocentric geostationary system of the Q point position to the ENU system can be obtained by bringing the coordinate under the geocentric geostationary system into a formula (1.10)
Comprises the following steps:
target calculation by equation (1.11)
In ENU coordinates with Q as origin:
conversion parameters from a device system (DEV system) to an ENU system are calculated based on an arbitrary angle space coordinate conversion model and coordinates of the ENU system and control points under the device system.
The traditional boolean sand model is not applicable because of the large rotation angles that may exist between the plant system and the geographical coordinate system. The rotation model using the euler angle has a problem of singular values, and therefore an arbitrary angle space coordinate conversion model based on a unit quaternion is selected to be used here.
Unit quaternion usage
Is shown in which
3 x 3 rotation matrix using unitary quaternion representation
As shown in formula (2.1):
is provided with
Is a point set under the device,
Points with the same index i for the point set under ENU system (g system)
And
namely the same-name points under different coordinate systems. The conversion formula from the device system to the ENU coordinate system is as follows (2.2):
now ask for
Is constructed with respect to (2.3)
Minimum mean square error objective function of (c):
cross covariance matrix sigma of device system D and geography system G dg Comprises the following steps:
using inter-covariance matrix sigma dg Forming an antisymmetric matrix
And defines a column vector Δ = [ A ] 23 A 31 A 12 ] T . Defining a 4 × 4 symmetric matrix Q (Σ) dg ) Comprises the following steps:
wherein I 3 Is a 3 × 3 identity matrix. Rotate
The optimal estimation vector of (d) is Q (sigma) dg ) The maximum eigenvalue of (2) is corresponding to the eigenvector. Optimal estimation vector for translation
Comprises the following steps:
three-dimensional coordinate conversion parameters from the device system to the ENU coordinate system can be solved by (2.6) and (2.7):
based on conversion parameters
And coordinates of n underwater targets 3 under the DEV system, and calculating a reference value of the coordinates of the underwater targets 3 under the ENU system
Based onReference value of n underwater target 3 coordinates under ENU system
And measured value
Calculating the difference value delta = [ delta ] of the underwater point cloud in the east-north-sky direction E δ N δ U ] T And sum error σ = [ σ ] E σ N σ U ] T And evaluating the consistency of the cloud point data of the underwater on the water. Note the book
If the stereo target device is observed repeatedly m times, the difference value and the error in the east-north-sky direction of the ith time are respectively recorded as: delta i And σ i . The reproducibility of the stereoscopic target device was obtained from (4.2):
the structure designed by the three-dimensional target device can be expanded as required, is not limited to the current structure, the target can be replaced by other shapes, the spherical target ball has better structural characteristics, the radius can be used for constraint, and the accuracy of calculating the coordinates of the center of the ball is improved.
It is to be understood that the above description is not intended to limit the present invention, and the present invention is not limited to the above examples, and those skilled in the art may make modifications, alterations, additions or substitutions within the spirit and scope of the present invention.
Claims (9)
1. An overwater and underwater point cloud consistency assessment method based on multi-target three-dimensional connection is characterized by comprising the following steps:
s1, manufacturing a three-dimensional target device;
s2, collecting overwater and underwater point cloud data of the three-dimensional target device;
s3, evaluating consistency of the point cloud above and below water;
s3.1, calculating a measured value of a target center coordinate in the three-dimensional target device under an ENU system by using a spherical fitting algorithm based on radius constraint, wherein the ENU system is a northeast coordinate system;
s3.2, calculating conversion parameters from the DEV system to the ENU system based on an arbitrary angle space coordinate conversion model and target center coordinates of the ENU system and the DEV system, wherein the DEV system is a three-dimensional target device system;
s3.3, calculating a reference value of the target center coordinate in the ENU system based on the conversion parameter and the coordinate of the target center in the DEV system;
and S3.4, calculating the difference and the mean error of the underwater point cloud in the east-north-sky direction based on the reference value and the measured value of the target center coordinate under the ENU system, and evaluating the consistency of the underwater point cloud on the water.
2. The method for evaluating consistency of the cloud point above and below water based on multi-target three-dimensional connection according to claim 1, wherein the three-dimensional target device in the step S1 is specifically as follows:
the three-dimensional target device comprises a target and a connecting piece, wherein a space polyhedron is formed by more than 5 rigidly connected targets, the target is in a regular shape, the center of the target can be defined as a mass center, a centroid or other people as a specified position, the size of the target is determined according to the measurement resolution of different shipborne water and underwater integrated systems, and the target is specifically a target ball;
the connecting piece is used for supporting and fixing the targets, rigid connection between the targets is guaranteed, the space structure of the three-dimensional target device ensures that the targets are not or less shielded by the connecting piece, and the targets can form a plurality of planes in different directions for consistency evaluation.
3. The multi-target stereo connection based cloud consistency of underwater and water points on water surface as claimed in claim 2The evaluation method is characterized in that the three-dimensional target device measures the spatial relative position relation of each target, parameters in machining design are directly used under the condition that the precision requirement of the target position is not high, a total station, an industrial measurement system or a three-dimensional laser scanner is used for calibrating the spatial position of each target ball in the three-dimensional target device under the condition that the precision requirement is high, and the coordinates of the target under the device system are represented as follows: [ x ] of d y d z d ] T 。
4. The method for evaluating consistency of the cloud point above and below water based on multi-target stereo connection according to claim 3, wherein S2 comprises:
the three-dimensional target device is placed in water, the part above the water surface is guaranteed to have planes which are not less than 4 targets and are formed in different directions, the part below the water surface is not less than 1 target, the three-dimensional target device is scanned by the laser radar above the water surface and the underwater multi-beam simultaneously, the targets above the water surface are guaranteed to be scanned by the laser radar, and the targets below the water surface are scanned by the multi-beam.
5. The method for evaluating consistency of cloud points above and below water based on multi-target stereo connection according to claim 4, wherein S3.1 comprises:
extracting targets in the point cloud from the overwater and underwater point cloud data of the three-dimensional target device in the S2 in a manual or automatic mode, and calculating to obtain approximate coordinates of the centers of the targets in a least square mode;
the spherical equation of space is:
(x i -x) 2 +(y i -y) 2 +(z i -z) 2 ＝r 2 (1.1)
(x, y, z) and r are the sphere center coordinates and radius, respectively, (x) i ，y i ，z i ) Is a spherical point coordinate;
expanding and transposing the formula (1.1) can obtain:
recording:
(x 1 ，y 1 ，z 1 )，(x 2 ，y 2 ，z 2 )，…，(x n ，y n ，z n ) Coordinates of n spherical points, respectively;
solving an over-determined equation and recording the solution as an approximate sphere center value (x) of the target 0 ，y 0 ，z 0 ) And approximate radius r of the target 0 。
6. The method for evaluating consistency of the cloud point above and below water based on multi-target stereo connection according to claim 5, wherein the step S3.1 comprises:
calculating the measurement coordinate of the target center in the three-dimensional target device under the ENU system by using a spherical fitting algorithm based on radius constraint and the approximate coordinate value of the target center;
the following function is constructed:
to (1.4) formula in (x) 0 ，y 0 ，z 0 ，r 0 ) The process linearization yields:
spherical radius constraint equation:
r d +V d ＝r 0 +δr＝r (1.6)
i represents the number of spherical points; r is d Is a design value of the target sphere radius; v d Design value r for target d The number of corrections of (a);
[δx δy δz δr] T ＝[(x-x 0 ) (y-y 0 ) (z-z 0 ) (r-r 0 )] T ；
l =0 as observed value;
v is the correction number of the observed value;
simultaneous (1.5) and (1.6) formulas are written in matrix form:
in the formula (I), the compound is shown in the specification,
from the ith spherical point to the approximate center of sphere (x) 0 ，y 0 ，z 0 ) The number of corrections of (a);
solving equation (1.7) using the indirect adjustment method, the following matrix is defined:
wherein the weight matrix P is a weight matrix I represented by the formula (1.5) n×n And a weight matrix P of the formula constraint conditional equation (1.6) c Composition of = 10;
obtained parameter x 0 ，y 0 ，z 0 ，r 0 The correction numbers δ x, δ y, δ z, δ r:
[δx δy δz δr] T ＝(B T PB) -1 B T Pl (1.8)
approximate coordinates of the center and the radius of the target sphere are set as iteration initial values, and delta r is less than epsilon r Design value r for termination condition of iteration 0 Error of (e) r The requirement is met after 2-3 iterations;
the adjustment results are:
the measured values of the coordinates of the n targets in the device under the earth-centered earth-fixed system are recorded as
Defining one target as the ENU system origin Q of the device, and the coordinates of the other m targets in the ENU system with Q as the origin are:
7. the method for evaluating consistency of cloud points above and below water based on multi-target stereo connection according to claim 6, wherein S3.2 comprises:
calculating conversion parameters from the DEV system to the ENU system based on an arbitrary angle space coordinate conversion model and coordinates of an overwater target under the ENU system and the DEV system, wherein a rotation matrix of the conversion parameters is expressed as
The translation vector of the coordinate system is
8. The method for evaluating consistency of the cloud point above and below water based on multi-target stereo connection according to claim 7, wherein S3.3 comprises:
calculating reference values of coordinates of the underwater target under the ENU system by using conversion parameters from the DEV system to the ENU system and coordinates of the n underwater targets under the DEV system
In the formula (I), the compound is shown in the specification,
coordinates of an underwater target under DEV.
9. The method for evaluating consistency of the cloud point above and below water based on multi-target stereo connection according to claim 8, wherein S3.4 comprises:
reference value based on n underwater target coordinates under ENU system
And measured value
Calculating the difference value delta = [ delta ] of the underwater point cloud in the east-north-sky direction E δ N δ U ] T And sum error σ = [ σ ] E σ N σ U ] T Evaluating the consistency of the cloud point data on water and underwater, and recording
If the stereo target device is observed repeatedly m times, the difference value and the error in the east-north-sky direction of the ith time are respectively recorded as: delta i And σ i The reproducibility of the three-dimensional target device is obtained from (4.2):
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| CN104048465A (en) * | 2014-05-08 | 2014-09-17 | 苏州安特实业有限公司 | Freezer with ice cream bricks |
| CN104835144A (en) * | 2015-04-09 | 2015-08-12 | 云南大学 | Solving camera intrinsic parameter by using image of center of sphere and orthogonality |
| CN105205824A (en) * | 2015-09-25 | 2015-12-30 | 北京航空航天大学 | Multi-camera global calibration method based on high-precision auxiliary cameras and ball targets |
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Application publication date: 20221014 Assignee: Qingdao Haizhuo Tongchuang Technology Co.,Ltd. Assignor: SHANDONG University OF SCIENCE AND TECHNOLOGY Contract record no.: X2024980006470 Denomination of invention: A method for evaluating the consistency of point clouds above and below water based on multi target stereo connection Granted publication date: 20230926 License type: Common License Record date: 20240530 |