CN115183748B - Water-borne and underwater point cloud consistency assessment method based on multi-target three-dimensional connection - Google Patents

Water-borne and underwater point cloud consistency assessment method based on multi-target three-dimensional connection Download PDF

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CN115183748B
CN115183748B CN202210727443.5A CN202210727443A CN115183748B CN 115183748 B CN115183748 B CN 115183748B CN 202210727443 A CN202210727443 A CN 202210727443A CN 115183748 B CN115183748 B CN 115183748B
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石波
赵凯
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Shandong University of Science and Technology
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Abstract

The invention discloses a method for evaluating consistency of point clouds on water and under water based on multi-target three-dimensional connection, which belongs to the technical field of measurement azimuth and is used for evaluating consistency of point cloud data and comprises the following steps: respectively acquiring a water part laser point cloud and an underwater part multi-beam point cloud of the device by using a water-on-water-under-water integrated measurement system, and acquiring a measured value of a center coordinate of a water-on-water-under-water target of an ENU system by using a spherical fitting algorithm based on radius constraint; calculating conversion parameters between an ENU system and a DEV system by using a design value, a measured value and a space coordinate conversion model of a central coordinate of a water target at any angle; calculating a reference value of the center coordinate of the underwater target under the ENU system by using a design value of the center coordinate of the underwater target and a conversion parameter from the DEV system to the ENU system; and comparing the reference value and the measured value of the central coordinate of the underwater target in the ENU system, and calculating the difference value and the middle error of the central coordinate component of the underwater target in the east-north-heaven direction.

Description

Water-borne and underwater point cloud consistency assessment method based on multi-target three-dimensional connection
Technical Field
The invention discloses a method for evaluating consistency of underwater point clouds on water based on multi-target three-dimensional connection, and belongs to the technical field of measuring azimuth.
Background
In the operation of the shipborne underwater integrated measuring system, due to the limitations of factors such as the working performance of a sensor, the installation position of the sensor, the draught of a ship, tides, underwater topography and the like, certain gaps and misplacement exist between the underwater point cloud and the water point cloud, so that people need to accurately evaluate the splice gap of the underwater point cloud and evaluate the misplacement condition of the underwater point cloud, and the two aspects are collectively called the underwater point cloud consistency. The consistency of the point cloud marks the measurement precision of the water-on-water-under-water integrated measurement system. The existing method for evaluating the splice joints of the point clouds mainly relies on a method for manually measuring markers, a large number of uniform and easily-distinguished on-water and off-water point cloud groups are selected from different areas, and gap spacing is manually measured by using point cloud visualization software. The method for manually measuring the markers mainly adopts a manual interaction mode, the point cloud visualization software is used for selecting the sizes and the position relations of the manually measured splicing seams of the markers on the bank or in water, and the manually selected characteristic points have high randomness and the consistency of multiple measurements is difficult to ensure. The filtering and thinning processes in the data post-processing process may cause some characteristic points to be missing, so that the measurement result is deviated.
Disclosure of Invention
The invention discloses a multi-target three-dimensional connection-based method for evaluating consistency of point clouds on water and underwater, which aims to solve the problems of high randomness and low precision caused by evaluating consistency of point cloud data by manually measuring markers in the prior art.
A multi-target three-dimensional connection-based method for evaluating consistency of underwater point clouds on water comprises the following steps:
s1: manufacturing a three-dimensional target device;
s2: collecting water-borne and underwater point cloud data of a three-dimensional target device;
s3: evaluating consistency of underwater point clouds;
s3.1, calculating a measurement coordinate of a 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 arbitrary angle space coordinate conversion model and coordinates of the center of the ENU system and the launching target of the device system;
s3.3 calculating a reference value of the center coordinates of the underwater target under the ENU system based on the conversion parameters and the coordinates of the center of the underwater target under the device system
And S3.4, calculating the difference value and the middle error of the underwater point cloud in the east-north-sky direction based on the reference value and the measured value of the central coordinate of the underwater target under the ENU system, and evaluating the consistency of the underwater point cloud data on water.
Preferably, the manufacturing requirements of the stereoscopic target device in the step S1 are as follows:
the three-dimensional target device comprises a target and a connecting piece, wherein a space polyhedron is formed by 5 or more targets which are rigidly connected, the target is in a regular shape, the center of the target can be defined as a centroid, a centroid or other manually designated positions, and the size of the target needs to consider the measurement resolution of different shipborne water-borne water-under-water integrated systems;
the connecting piece is used for supporting and fixing targets and guaranteeing rigid connection between the targets.
The spatial structure of the three-dimensional target device should ensure that the target is not or is less blocked by the connecting piece, and the target should form a plurality of planes with different orientations for consistency evaluation;
the three-dimensional target device is used for determining the spatial relative position relation of each target, defining a three-dimensional target device system, directly using parameters in machining design under the condition of low target position accuracy requirement, and calibrating the spatial position of each target ball in the three-dimensional target device by using a total station, an industrial measurement system or a three-dimensional laser scanner under the condition of high accuracy requirement;
preferably, the acquiring of the point cloud data of the stereoscopic target device in step S2 includes:
the three-dimensional target device is arranged in water, so that the upper part of the water surface is required to be provided with planes in different directions formed by at least 4 targets, and the lower part of the water surface is required to be provided with at least 1 target.
The device for simultaneously scanning the three-dimensional targets by using the above-water laser radar and the underwater multi-beam in the shipborne above-water and underwater integrated measuring system is used for ensuring that targets above the water surface are scanned by the laser radar and 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) manually or automatically, and calculating the approximate coordinates of the center of the target by a least square mode.
The spherical equation for 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 center coordinates and radius, respectively. (x) i ,y i ,z i ) Is spherical point coordinates.
The method comprises the following steps of (1.1) expanding and shifting:
note that:
wherein, (x) 1 ,y 1 ,z 1 ),(x 2 ,y 2 ,z 2 ),…,(x n ,y n ,z n ) The coordinates of n sphere points, respectively.
Solving the overdetermined equation as follows, and recording the solution as the sphere center approximation (x 0 ,y 0 ,z 0 ) And approximate radius r of target 0 。
X＝(B T B) -1 B T Y (1.3)
Preferably, step S3.1 comprises:
calculating the measurement coordinates of the target center in the device under the ENU system by using the spherical fitting algorithm based on radius constraint and the approximate coordinate values of the target center acquired in the step 4.
The following function was constructed:
for formula (1.4) in (x 0 ,y 0 ,z 0 ,r 0 ) The linearization at this point can be obtained:
spherical radius constraint equation:
r d +V r ＝r 0 +δr＝r (1.6)
in the middle of
i represents the number of the sphere point;
V d design value r for target d Is the correction of (a);
r d the design value of the radius of the target sphere is set;
the distance from the sphere point to the initial sphere center;
[δx δy δz δr] T ＝[(x-x 0 )(y-y 0 )(z-z 0 )(r-r 0 )] T ；
l=0 is considered as an observed value;
v is the correction of the observed value;
simultaneous (1.5) and (1.6) are written in matrix form:
in the method, in the process of the invention,
solving (1.7) by using an indirect adjustment method, and defining the following matrix:
wherein the weight matrix P is represented by a weight matrix I of the formula (1.5) n×n And constraint equation (1.6) weight array P c Composition =10.
The obtained parameter x 0 ,y 0 ,z 0 ,r 0 Is a modification of (a)Positive numbers δx, δy, δz, δr:
[δx δy δz δr] T ＝(B T PB) -1 B T Pl (1.8)
and (4) making the approximate coordinates of the center and the radius of the target calculated in the step (4) be iteration initial values. δr<ε r (design value r 0 Error epsilon of (2) r ) Is an abort condition for the iteration. The requirements can be met generally through 2-3 iterations.
Thus, the adjustment results are:
the measured values of n target coordinates in the geocentric earth-fixed system device are recorded as
Defining an origin Q of a northeast (ENU) geographic system (g-system) of which one target is a device, wherein the coordinates of other m targets at the ENU with the origin Q are as follows:
preferably, step S3.2 comprises:
based on the arbitrary angle space coordinate transformation model and the coordinates of the ENU system and the device system (DEV system) launching target, the transformation parameters from the device system to the ENU system are calculated, and the rotation matrix is expressed asThe coordinate system translation vector is +.>
Preferably, step S3.3 comprises:
n underwater under a device train (DEV train) and conversion parameters acquired using the S.2 stepCoordinates of the target, calculating reference values of coordinates of the underwater target in the ENU system
Preferably, step S3.4 comprises:
reference values based on n underwater target coordinates in ENU systemAnd measured valueCalculating the difference delta= [ delta ] of the underwater point cloud in the east-north-sky direction E δ N δ U ] T Sum error σ= [ σ ] E σ N σ U ] T And evaluating the consistency of the underwater point cloud data. Record->
If the stereoscopic target device is repeatedly observed m times, the difference and the middle error of the ith time in the east-north-sky direction are respectively recorded as: delta i Sum sigma i . The reproducibility of the stereoscopic target device is available from (4.2):
the invention has the following advantages: compared with the prior art, the method has the advantages that the target is used for replacing natural features, the consistency of feature selection in multiple measurement is ensured, the method for obtaining the target coordinates by using target fitting is used for replacing the traditional method for manually selecting the point cloud corner points, and the consistency of the result of evaluating the dislocation and the gap of the underwater point cloud on water is ensured; the three-dimensional target device is used for fixing the relative position relation among a plurality of targets, a measurable device system is formed, and the conversion relation between the device system and the geocentric ground fixed system can be accurately obtained through measuring the targets of the reference part, so that the difference value between the underwater target measured value and the theoretical value is obtained.
Drawings
FIG. 1 is a technical flow chart of the present invention;
FIG. 2 is a block diagram of a stereoscopic targeting device of the present invention;
the reference numerals include: 1-connector, 2-water target, 3-underwater target.
Detailed Description
The invention is described in further detail below with reference to the attached drawings and detailed description:
noun explanation of several techniques related to the invention:
and (3) point cloud data: and acquiring a set of mass points of the surface features of the target object by using a measuring instrument, wherein the point cloud data comprise information such as space three-dimensional coordinates, reflection intensity and the like.
Multi-beam point cloud data: refers to point cloud data of a sub-sea terrain surface acquired using a multi-beam sounding system.
Laser point cloud data: refer to point cloud data of the surface of the ground surface feature acquired by using a laser scanner.
Shipborne water-borne underwater integrated measurement system: the method is used for carrying out integrated measurement from submarine topography to coastal topography under the same measurement standard through the integration of equipment such as a multi-beam depth finder, a laser scanner, marine vessel positioning navigation and the like.
A multi-target three-dimensional connection-based method for evaluating consistency of point clouds on water and under water is shown in fig. 1, and comprises the following steps:
s1: manufacturing a three-dimensional target device;
s2: collecting water-borne and underwater point cloud data of a three-dimensional target device;
s3: evaluating consistency of underwater point clouds;
s3.1, calculating a measurement coordinate of a 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 arbitrary angle space coordinate conversion model and coordinates of the center of the ENU system and the launching target of the device system;
s3.3 calculating a reference value of the center coordinates of the underwater target under the ENU system based on the conversion parameters and the coordinates of the center of the underwater target under the device system
And S3.4, calculating the difference value and the middle error of the underwater point cloud in the east-north-sky direction based on the reference value and the measured value of the central coordinate of the underwater target under the ENU system, and evaluating the consistency of the underwater point cloud data on water.
The technical scheme related to the invention is divided into 3 technical links for analysis:
step 1, manufacturing a three-dimensional target device:
the three-dimensional target device comprises a target and a connecting piece 1, wherein a space polyhedron is formed by 5 or more targets which are rigidly connected, the target is in a regular shape, the center of the target can be defined as a centroid, a centroid or other manually designated positions, and the size of the target needs to consider the measurement resolution of different shipborne water-borne water-under-water integrated systems;
the connecting piece 1 is used for supporting and fixing targets and guaranteeing rigid connection between the targets.
The spatial structure of the three-dimensional target device should ensure that the target is not or is less blocked by the connecting piece 1, and the target should form a plurality of planes with different orientations for consistency evaluation;
the three-dimensional target device is used for determining the spatial position relation of each target, defining a three-dimensional target device system, directly using parameters in machining design under the condition of low target position accuracy requirement, and calibrating the spatial position of each target ball in the three-dimensional target device by using a total station, an industrial measurement system or a three-dimensional laser scanner under the condition of high accuracy requirement;
according to the requirements for manufacturing the three-dimensional target device, a reference three-dimensional target device is provided, as shown in figure 2, 6 targets of the underwater part are 1-6 numbers, 4 targets of the water part are 7-10, and the calibration results are shown in table 1.
Table 1 target coordinates (sphere center) under the stereoscopic target device system
Sequence number Type(s) 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
Step 2, collecting the water-borne and underwater point clouds of the three-dimensional target device:
the three-dimensional target device is arranged in water, so that the part above the water surface needs to be provided with planes in different directions formed by at least 3 targets, and the underwater part is not less than 1 target.
The device for simultaneously scanning the three-dimensional targets by using the water laser radar and the underwater multi-beam in the ship-borne water-on-water-under-water integrated measuring system is used for scanning targets above the water surface by the laser radar and scanning targets below the water surface by the multi-beam.
Step 3, water-borne and underwater point cloud consistency assessment:
and calculating the measurement coordinates of the target center in the device under the ENU system by using the data obtained by scanning in the step 2 based on the spherical fitting algorithm of radius constraint.
First, the approximate coordinates of the target in the geocentric earth's fixed system are calculated.
The spherical equation for 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 center coordinates and radius, respectively. (x) i ,y i ,z i ) Is spherical point coordinates.
The method comprises the following steps of (1.1) expanding and shifting:
note that:
wherein, (x) 1 ,y 1 ,z 1 ),(x 2 ,y 2 ,z 2 ),…,(x n ,y n ,z n ) The coordinates of n sphere points, respectively.
Solving the overdetermined equation as follows, and recording the solution as the sphere center approximation (x 0 ,y 0 ,z 0 ) And approximate radius r of target 0 。
X＝(B T B) -1 B T Y (1.3)
Secondly, calculating the measurement coordinates of the target center in the device under the geocentric ground system by using a spherical fitting algorithm based on radius constraint and the approximate coordinate values of the target center acquired in the previous step.
The following function was constructed:
for formula (1.4) in (x 0 ,y 0 ,z 0 ,r 0 ) The linearization at this point can be obtained:
spherical radius constraint equation:
r d +V r ＝r 0 +δr＝r (1.6)
in the middle of
i represents the number of the sphere point;
V d design value r for target d Is the correction of (a);
r d the design value of the radius of the target sphere is set;
the distance from the sphere point to the initial sphere center;
[δx δy δz δr] T ＝[(x-x 0 )(y-y 0 )(z-z 0 )(r-r 0 )] T ；
l=0 is considered as an observed value;
v is the correction of the observed value;
simultaneous (1.5) and (1.6) are written in matrix form:
in the method, in the process of the invention,
solving (1.7) by using an indirect adjustment method, and defining the following matrix:
wherein the weight matrix P is represented by a weight matrix I of the formula (1.5) n×n And constraint equation (1.6) weight array P c Composition =10.
The obtained parameter x 0 ,y 0 ,z 0 ,r 0 The correction numbers δx, δy, δz, δr:
[δx δy δz δr] T ＝(B T PB) -1 B T Pl (1.8)
and (4) making the approximate coordinates of the center and the radius of the target calculated in the step (4) be iteration initial values. δr<ε r (design value r 0 Error epsilon of (2) r ) Is an abort condition for the iteration. The requirements can be met generally through 2-3 iterations.
Thus, the adjustment results are:
the measured values of n target coordinates in the geocentric earth-fixed system device are recorded as
Finally, the target is converted from the ECEF coordinate system to the ENU coordinate system.
Defining an origin Q of a northeast (ENU) geographic system (g-system) of which one target is a device, wherein the coordinates of other m targets at the ENU with the origin Q are as follows:calculating geographical coordinates +.>With ECEF coordinatesλ is the geographical longitude, +.>For geographic latitude, the formula for solving geographic coordinates by using rectangular coordinates of the earth center is as follows:
atan2 (x, y) is a function for calculating the arctangent value of a given horizontal and vertical coordinate point, and the value range is (-pi, pi)]，R e And e represents the ellipse major-minor axis and ellipse eccentricity respectively, let the iteration initial value t 0 =0, and can reach enough numerical calculation accuracy after 5 to 6 iterations, and then t is i+1 Inverse tangentCan obtain latitude->
Defining an underwater target 3 as the origin Q, lambda of the northeast-North-day (ENU) geographical system (g-system) of the device Q For the geographic longitude of point Q,for the geographic latitude of point Q,bringing its coordinates under the geocentric fixation into (1.10) can obtain the coordinate transformation matrix of the geocentric fixation to the ENU system at the Q point position +.>The method comprises the following steps:
calculation of targets by (1.11)At the ENU coordinate with Q as origin:
based on the arbitrary angular space coordinate transformation model and the coordinates of the control points under the ENU system and the device system, transformation parameters from the device system (DEV system) to the ENU system are calculated.
The conventional boolean sand model is not applicable because of the large rotation angles that may exist between the system of devices 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 usageRepresentation of wherein3X 3 rotation matrix represented by unit quaternion +.>As formula (2.1):
for the coordinate system translation vector, the conversion parameters from the device system to the ENU system +.>The method comprises the following steps:
is provided withPoint set for device tying, +.>For the point set under ENU series (g series), the points with the same index i are +.>And->Namely, the same name points under different coordinate systems. The conversion formula from the device system to the ENU coordinate system is as formula (2.2):
now ask forIs constructed from (2.3) for +.>Is a minimum mean square error objective function of (a):
and->Centroid of device and geographic sets of points, respectively:
device system D and geographic system G dg The method comprises the following steps:
using a mutual covariance matrix Σ dg Forming an antisymmetric matrixAnd defines a column vector Δ= [ a ] 23 A 31 A 12 ] T . Defining a 4 x 4 symmetric matrix Q (Σ dg ) The method comprises the following steps:
wherein I is 3 Is a 3 x 3 identity matrix. RotatingIs Q (Σ) dg ) A feature vector corresponding to the maximum feature value of (a). Optimal estimate vector of translation->The method comprises the following steps:
three-dimensional coordinate transformation parameters from the device system to the ENU coordinate system can be solved from (2.6) and (2.7):
based on conversion parametersAnd coordinates of n underwater targets 3 in the device system (DEV system), calculating reference values +.>
Reference value based on 3 coordinates of n underwater targets in ENU systemAnd measured valueCalculating the difference delta= [ delta ] of the underwater point cloud in the east-north-sky direction E δ N δ U ] T Sum error σ= [ σ ] E σ N σ U ] T And evaluating the consistency of the underwater point cloud data. Record->
If the stereoscopic target device is repeatedly observed m times, the difference and the middle error of the ith time in the east-north-sky direction are respectively recorded as: delta i Sum sigma i . The reproducibility of the stereoscopic target device is available 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 good structural characteristics, the radius can be used for constraint, and the accuracy of calculating the coordinates of the sphere center is improved.
It should be understood that the above description is not intended to limit the invention to the particular embodiments disclosed, but to limit the invention to the particular embodiments disclosed, and that the invention is not limited to the particular embodiments disclosed, but is intended to cover modifications, adaptations, additions and alternatives falling within the spirit and scope of the invention.

Claims (1)

1. The method for evaluating the consistency of the underwater point clouds on water based on multi-target three-dimensional connection is characterized by comprising the following steps of:
s1, manufacturing a three-dimensional target device;
s2, collecting water-borne and underwater point cloud data of the three-dimensional target device;
s3, evaluating consistency of underwater point clouds on 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 a DEV system to an ENU system based on an arbitrary angle space coordinate conversion model and a target center coordinate under the ENU system and the DEV system, wherein the DEV system is a three-dimensional target device coordinate system;
s3.3, calculating a reference value of a target center coordinate under an ENU system based on the conversion parameters and the coordinate of the target center under the DEV system;
s3.4, calculating the difference value and the middle 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 water;
the three-dimensional target device in S1 specifically comprises:
the three-dimensional target device comprises a target and a connecting piece, wherein a space polyhedron is formed by 5 or more targets which are rigidly connected, the target is in a regular shape, the center of the target is defined as a centroid or a centroid, the size of the target is determined according to the measurement resolution of different shipborne water-borne water-under-water integrated systems, and the target is specifically a target ball;
the connecting piece is used for supporting and fixing targets, rigid connection between the targets is guaranteed, the space structure of the three-dimensional target device ensures that the targets are not shielded by the connecting piece, and the targets can form a plurality of planes with different orientations for consistency evaluation; the three-dimensional target device measures the spatial relative position relation of each target, directly uses the parameter during the mechanical processing design, or uses the total station, the industrial measurement system or the three-dimensional laser scanner to calibrate the spatial position of each target ball in the three-dimensional target device, and the coordinates of the targets under the coordinate system of the three-dimensional target device are expressed as follows: [ x ] d y d z d ] T ；
S2 comprises the following steps:
the three-dimensional target device is arranged in water, so that the upper part of the water surface is guaranteed to have planes in different directions formed by at least 4 targets, the lower part of the water is guaranteed to have at least 1 target, the above-water laser radar and the underwater multi-beam are used for scanning the three-dimensional target device at the same time, and 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; s3.1 comprises:
extracting targets in the point cloud from the water-borne 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 through a least square mode;
the spherical equation for 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 center of sphere coordinates and radius, respectively, (x) i ，y i ，z i ) Spherical point coordinates;
the method comprises the following steps of (1.1) expanding and shifting:
and (3) recording:
(x 1 ，y 1 ，z 1 )，(x 2 ，y 2 ，z 2 )，…，(x n ，y n ，z n ) Coordinates of n sphere points, respectively;
solving the overdetermined equation and recording the solution as the sphere center approximation (x 0 ，y 0 ，z 0 ) And approximate radius r of target 0 The method comprises the steps of carrying out a first treatment on the surface of the Step S3.1 comprises:
calculating a measurement coordinate of the target center in the three-dimensional target device under an ENU system by using a spherical fitting algorithm based on radius constraint and an approximate coordinate value of the target center;
the following function was constructed:
for formula (1.4) in (x 0 ，y 0 ，z 0 ，r 0 ) The linearization at this point can be obtained:
spherical radius constraint equation:
r d +V d ＝r 0 +δr＝r (1.6)
i represents the number of the sphere point; r is (r) d The design value of the radius of the target sphere is set; v (V) d Design value r for target sphere radius d Is the correction of (a);
the distance from the sphere point to the initial sphere center;
[δx δy δz δr] T ＝[(x-x 0 ) (y-y 0 ) (z-z 0 ) (r-r 0 )] T ；
l=0 is considered as an observed value;
v is the correction of the observed value;
simultaneous (1.5) and (1.6) are written in matrix form:
in the method, in the process of the invention, from the ith sphere point to the approximate sphere center (x 0 ，y 0 ，z 0 ) Is the correction of (a);
solving (1.7) by using an indirect adjustment method, and defining the following matrix:
obtaining the parameter x 0 ，y 0 ，z 0 ，r 0 The correction numbers δx, δy, δz, δr:
[δx δy δz δr] T ＝(B T PB) -1 B T Pl (1.8)
wherein P represents a weight matrix, and B represents a coefficient matrix;
the approximate coordinates of the sphere center and the radius of the target are iteration initial values, delta r < epsilon r For the suspension condition of iteration, the value r is designed 0 Error epsilon of (2) r The requirement is met after 2 to 3 iterations;
the adjustment results are:
the measurement values of n target coordinates in the three-dimensional target device under the geocentric geodetic coordinate system are recorded as
Defining an ENU system origin Q of which one target is a three-dimensional target device, and coordinates of other m targets in the ENU system taking Q as the origin are as follows:s3.2 comprises:
based on the arbitrary angle space coordinate conversion model and the coordinates of the ENU system and the DEV system launching target, calculating the coordinate system conversion parameters from the DEV system to the ENU system, wherein the rotation matrix of the coordinate system conversion parameters is expressed asTranslation vector of coordinate system conversion parameter is +.>S3.3 comprises:
calculating a reference value of the center coordinates of the underwater targets in the ENU system by using the conversion parameters from the DEV system to the ENU system and the center coordinates of the n underwater targets in the DEV system
In the method, in the process of the invention,is the center coordinates of the underwater target under DEV system, < ->Representation->Components of (2); s3.4 comprises:
reference value based on central coordinates of n underwater targets in ENU systemAnd measured valueCalculating the difference delta= [ delta ] of the underwater point cloud in the east-north-sky direction E δ N δ U ] T Sum error σ= [ σ ] E σ N σ U ] T Evaluating the consistency of the point cloud data on water and under water, record +.>
If the stereoscopic target device is repeatedly observed m times, the difference and the middle error of the ith time in the east-north-sky direction are respectively recorded as: delta i Sum sigma i The reproducibility of the stereoscopic target device is available from (4.2):
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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
CN111145227A (en) * 2019-12-17 2020-05-12 北京建筑大学 Iterative integral registration method for multi-view point cloud in underground tunnel space

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
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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