阅读说明：本技术 一种用于远距离线缆位置参数的测量方法 (Method for measuring position parameters of long-distance cable ) 是由 黄捷洲 吴潮伟 梁运俊 刘家昶 祖基能 毕明校 董小锋 杨先盛 于 2020-10-16 设计创作，主要内容包括：本发明公开了一种用于远距离线缆位置参数的测量方法,在车体或装置两侧分别安装有相机,两个相机的连线与线缆垂直,两个相机的距离固定,相机镜头轴线与线缆所在水平面形成一夹角,在两个相机连线中间的车体上安装有一字线激光,两个相机镜头和一字线激光安装在同一个竖直平面上；包括以下步骤：S1、控制一字线激光发射激光照射线缆；S2、控制左右两个相机同时拍摄线缆的图像画面；S3、对图像进行预处理,去除噪点；S4、对步骤S3中经过预处理的图像进行图像识别,获取线缆光斑位置；S5、将光斑坐标代入公式,计算出需要测量的数据。本发明高效、准确、安全,能大大减少人力成本。(The invention discloses a method for measuring position parameters of a remote cable, wherein cameras are respectively arranged on two sides of a vehicle body or a device, the connecting line of the two cameras is perpendicular to the cable, the distance between the two cameras is fixed, an included angle is formed between the axis of a camera lens and the horizontal plane where the cable is located, a line laser is arranged on the vehicle body between the connecting lines of the two cameras, and the two camera lenses and the line laser are arranged on the same vertical plane; the method comprises the following steps: s1, controlling a line laser to emit laser to irradiate the cable; s2, controlling the left camera and the right camera to shoot the image pictures of the cable at the same time; s3, preprocessing the image and removing noise; s4, carrying out image recognition on the image preprocessed in the step S3 to obtain the cable light spot position; and S5, substituting the spot coordinates into a formula to calculate the data to be measured. The invention is efficient, accurate and safe, and can greatly reduce the labor cost.)

1. A method for measuring a position parameter of a remote cable, comprising: cameras are respectively arranged on two sides of a vehicle body or a device, the connecting line of the two cameras is perpendicular to a cable, the distance between the two cameras is fixed, the axis of a camera lens and the horizontal plane where the cable is located form an included angle, a line laser is arranged on the vehicle body between the connecting lines of the two cameras, and the two camera lenses and the line laser are arranged on the same plane; the cable type position parameter measuring method at least comprises the following steps:

s1, controlling a line laser to emit laser to irradiate the cable;

s2, controlling the left camera and the right camera to shoot the image pictures of the cable at the same time;

s3, preprocessing the image and removing noise;

s4, carrying out image recognition on the image preprocessed in the step S3 to obtain the cable light spot position;

and S5, substituting the spot coordinates into a formula, and calculating data to be measured.

2. The method for measuring the position parameters of the remote cable according to claim 1, further comprising a step S6 of sending the data calculated in the step S5 to the upper computer of the railway inspection robot through a communication protocol.

3. The method as claimed in claim 1, wherein a vehicle-mounted light source is provided on the vehicle body, and the color temperature of the light source can be adjusted.

4. The method as claimed in claim 1, wherein the denoising process is performed on the point of small noise in step S3 by using a morphological denoising method.

5. A method for measuring a remote cable location parameter as set forth in claim 1, wherein said image recognition in step S4 comprises the steps of:

s41, performing Gaussian smoothing operation on the image, then performing binarization, segmenting the binarized image, labeling a connected domain, and determining a legal cable coordinate according to the connected domain;

and S42, comparing the cable coordinates of the current frame with the cable coordinates of the previous N frames respectively, if the gradient of the coordinate change is within a given interval range, determining the cable coordinates as normal cable coordinates, transmitting the normal cable coordinates to a solver to perform space coordinate solution, and determining the solution value as the light spot coordinates.

6. The method for measuring the position parameter of the long-distance cable according to claim 5, wherein the step S41 comprises the following steps:

s411, if the obtained connected domains are proper in number and the area of each connected domain is within a given interval, calculating the center of each connected domain to serve as a cable coordinate, if the cable coordinate is within the given interval range, comparing the areas of the connected domains of the left view and the right view, and if the area difference is less than a given threshold value, determining that the cable coordinate is legal;

s412, if the number of the obtained connected domains is too small, changing the size of a Gaussian kernel and a binarization threshold value, then performing Gaussian smoothing and binarization on the original image again, and labeling the connected domains on the binarized image; executing step S411;

s412, if the number of the connected domains obtained at the moment is too large, performing self-adaptive binarization operation on the smoothed image, performing straight line detection, calculating the slope of each line segment, discarding the line segments of which the slopes are not within a given range, eliminating outlier line segments through an isolated forest algorithm, clustering the remaining line segments to obtain a plurality of line clusters, calculating the dispersion degree of each line cluster, if the dispersion degree is within an acceptable range, using the clustering centers as the centers of the respective line clusters, otherwise discarding the line segments far away from the clustering centers, and repeating the steps until the dispersion degree is within the acceptable range; the cluster center can be regarded as the center of the cable, the cluster discrete degree is converted into the radius of the cable according to a predefined rule, the positions of the candidate connected domains and the cable are compared, if the connected domains are located in the range of the cable and the area of each connected domain is within a given interval, the connected domains are light spots formed on the cable by the laser, and step S411 is executed.

7. The method according to claim 5, wherein the coordinate solving process in step S42 comprises:

s420, parameter setting

Setting the centers of the photosensitive films of the left camera and the right camera as O1 and O2; the focal length of the camera is f; the focal points of the left camera and the right camera are C1 and C2; the optical axes of the left camera and the right camera are respectively a connecting line of O1 and C1 and a connecting line of O2 and C2; the included angle between the optical axis and the plumb line is alpha; the distance between O1O 2 is the base length L; the midpoint of O1O 2 is O0;

the point to be measured in the space is P, and the coordinate of the point to be measured P under the binocular coordinate system is (x, y); the imaging points of the point P in the left camera negative and the right camera negative are A, B respectively, the distance from the imaging point A to the optical center O1 is x1, and the distance from the imaging point B to the optical center O2 is x 2;

s421, constructing a binocular system coordinate system;

constructing a binocular system coordinate system by taking O0 as an origin, O1O 2 as an x axis, wherein a vertical line is a y axis, the upward direction is a positive direction of the y axis, and the point from O0 to O2 is the positive direction of the x axis;

s422, constructing local coordinate systems of the left camera and the right camera;

respectively constructing local coordinate systems of the left camera and the right camera by taking O1 and O2 as original points, taking respective optical axes as y axes and taking the right side of the negative film as the positive direction of the x axis;

s423, constructing a transformation matrix from the local coordinate system of each of the two cameras to the coordinate system of the binocular system、；

Calibrating the two cameras binocular respectively to obtain respective internal parameter matrixes K1 and K2 of the left camera and the right camera and an external parameter matrix M between the internal parameter matrixes, obtaining the focal length f of the cameras from the internal parameter matrixes, obtaining the included angle alpha and the base length L from the external parameter matrixes, and further obtaining a conversion matrix from a local coordinate system of the two cameras to a coordinate system of the two cameras according to the alpha and the L、；

S424, obtaining coordinates of the light spots in the left image and the right image through image matching, and setting the coordinates as the coordinates respectively、(ii) a Obtaining the coordinate P of the light spot in the negative film through conversion_a、P_bFrom which x1, x2 are derived; wherein

；

S425, passing the transformation matrix、The coordinates of A, B, C1 and C2 are converted from the respective local coordinate systems to be represented under a binocular system coordinate system; and the coordinates of P are solved by combining the linear equations of AC1 and BC 2.

8. A method as claimed in claim 5, wherein the camera is an industrial camera.

9. The method according to claim 6, wherein the transformation matrix in step S423 is synthesized by a rotation matrix and a translation matrix, i.e. M = T · R, where T: translating the matrix; r: a rotation matrix with units orthogonal.

10. The method as claimed in claim 6, wherein in step S425, the linear equations of AC1 and BC2 are respectively:

=

=。

Technical Field

The invention belongs to the field of object distance measurement, and particularly relates to a method for measuring a position parameter of a long-distance cable.

Background

In recent years, the contact networks of transmission lines and railways in China grow rapidly. A large number of power transmission lines and railway contact network facilities enter a maintenance period in succession, and line safety and monitoring face pressure to be gradually increased. At present, line inspection is mainly completed in a mode of taking manual static inspection as a main part and taking a small number of dynamic detection vehicles as auxiliary parts, namely, a mode of 'manual + rail vehicle' integration. The traditional manual inspection mode has the defects of high labor intensity, low working efficiency, scattered detection data, insufficient precision, long line occupation time, particularly 'skylight period' which needs to be reserved and the like.

Currently, the following methods are used for measuring the height and the lateral displacement:

the method comprises the following steps: and carrying out contact type measurement by utilizing an angular displacement sensor and a pressure sensor. The angle change and the pressure change are linearly converted into corresponding electric quantities by applying an electric strain principle. The angular displacement sensor is arranged on a main shaft of the contact type measuring device or a four-bar linkage connected with the main shaft, an angle measuring signal can be directly obtained along with the rotation of the main shaft, and the change of the guide height is calculated according to the change of the angle. The pressure sensor is attached to the pantograph, and the pull-out value is calculated from the pressure distribution of the pantograph.

The second method comprises the following steps: laser phase-type non-contact measurement. The laser beam is amplitude-modulated at a frequency in the radio band, the phase delay generated once by the modulated light from the optical return line is measured, and the distance represented by the phase delay is converted based on the wavelength of the modulated light. And calculating the lead-up and pull-out values by using the measured distance value and the rotation angle of the laser range finder.

The above method has the following disadvantages and shortcomings:

in the first method, the rotation and synchronous response speed of the mechanical part of the contact type measuring device and the sensor is low, so that the measuring precision is low, the error is large, and meanwhile, the mechanical rotation of the sensor is easy to damage the pantograph.

The device of the second method needs manual participation, the device needs to be fixed on the rail during measurement, the alignment mode is mostly mechanical alignment, the measurement efficiency is low, the construction period is long, the labor consumption is high, and multi-point measurement is inconvenient.

With the arrival of the trend of 'robots', the application of the robots in the field of railway transportation is more and more extensive, the inspection robots gradually appear in railway operation and maintenance and gradually grow into operation and maintenance mastery, and the inspection robots are efficient, accurate and safe, so that the labor cost is greatly reduced, the inspection quality is improved, and intelligent inspection is realized.

Disclosure of Invention

The invention aims to overcome the defects in the prior art and provide the method for measuring the cable type position parameters, which is efficient, accurate and safe, can greatly reduce the labor cost.

In order to achieve the purpose, the invention adopts the following scheme: a method for measuring a position parameter of a remote cable, comprising: cameras are respectively arranged on two sides of a vehicle body, the connecting line of the two cameras is perpendicular to a track, the distance between the two cameras is fixed, the axis of a lens of each camera forms an included angle with the plane of the track, a line laser is arranged on the vehicle body between the connecting lines of the two cameras, and two camera mirrors and the line laser are arranged on the same plane; the cable type position parameter measuring method at least comprises the following steps:

s1, controlling a line laser to emit laser to irradiate the cable;

s2, controlling the left camera and the right camera to shoot the image pictures of the cable at the same time;

s3, preprocessing the image and removing noise;

s4, carrying out image recognition on the image preprocessed in the step S3 to obtain the cable light spot position;

and S5, substituting the spot coordinates into a formula, and calculating data to be measured.

As another improvement of the cable type position parameter measuring method for the railway network inspection robot, the method further comprises the step S6 of sending the data calculated in the step S5 to the equipment terminal through a communication protocol

As another improvement of the invention for measuring the position parameters of the remote cables, a vehicle-mounted light supplementing light source is arranged on the vehicle body.

As a further improvement of the present invention for measuring the remote cable position parameters, in step S3, a morphological denoising method is used to denoise the points with small noise.

As a further improvement of the present invention for the remote cable location parameter measurement, the image recognition described in step S4 includes the following steps:

s41, performing Gaussian smoothing operation on the image, then performing binarization, segmenting the binarized image, labeling a connected domain, and determining a legal cable coordinate according to the connected domain;

and S42, comparing the cable coordinates of the current frame with the cable coordinates of the previous n frames respectively, if the gradient of the coordinate change is within a given interval range, determining the cable coordinates as normal cable coordinates, transmitting the normal cable coordinates to a solver to perform space coordinate solution, and determining the solution value as the light spot coordinates.

As a further improvement of the present invention for measuring the position parameter of the long-distance cable, the step S41 specifically includes the following steps:

s411, if the obtained connected domains are proper in number and the area of each connected domain is within a given interval, calculating the center of each connected domain to serve as a cable coordinate, if the cable coordinate is within the given interval range, comparing the areas of the connected domains of the left view and the right view, and if the area difference is less than a given threshold value, determining that the cable coordinate is legal;

s412, if the number of the obtained connected domains is too small, changing the size of a Gaussian kernel and a binarization threshold value, then performing Gaussian smoothing and binarization on the original image again, and labeling the connected domains on the binarized image; executing step S411;

s412, if the number of the connected domains obtained at the moment is too large, performing self-adaptive binarization operation on the smoothed image, performing straight line detection, calculating the slope of each line segment, discarding the line segments of which the slopes are not within a given range, eliminating outlier line segments through an isolated forest algorithm, clustering the remaining line segments to obtain a plurality of line clusters, calculating the dispersion degree of each line cluster, if the dispersion degree is within an acceptable range, using the clustering centers as the centers of the respective line clusters, otherwise discarding the line segments far away from the clustering centers, and repeating the steps until the dispersion degree is within the acceptable range; the cluster center can be regarded as the center of the cable, the cluster discrete degree is converted into the radius of the cable according to a predefined rule, the positions of the candidate connected domains and the cable are compared, if the connected domains are located in the range of the cable and the area of each connected domain is within a given interval, the connected domains are light spots formed on the cable by the laser, and step S411 is executed.

As a further improvement of the cable type position parameter measurement method for the railway network inspection robot of the present invention, the coordinate solving process in step S42 includes:

s420, parameter setting

Setting the centers of the photosensitive films of the left camera and the right camera as O1 and O2; the focal length of the camera is f; the focal points of the left camera and the right camera are C1 and C2; the optical axes of the left camera and the right camera are respectively a connecting line of O1 and C1 and a connecting line of O2 and C2; the included angle between the optical axis and the plumb line is alpha; the distance between O1O 2 is the base length L; the midpoint of O1O 2 is O0;

the point to be measured in the space is P, and the coordinate of the point to be measured P under the binocular coordinate system is (x, y); the imaging points of the point P in the left camera negative and the right camera negative are A, B respectively, the distance from the imaging point A to the optical center O1 is x1, and the distance from the imaging point B to the optical center O2 is x 2;

s421, constructing a binocular system coordinate system;

constructing a binocular system coordinate system by taking O0 as an origin, O1O 2 as an x axis, wherein a vertical line is a y axis, the upward direction is a positive direction of the y axis, and the point from O0 to O2 is the positive direction of the x axis;

s422, constructing local coordinate systems of the left camera and the right camera;

respectively constructing local coordinate systems of the left camera and the right camera by taking O1 and O2 as original points, taking respective optical axes as y axes and taking the right side of the negative film as the positive direction of the x axis;

s423, constructing a transformation matrix M from the local coordinate system of each of the two cameras to the coordinate system of the binocular system_1to0、M_2to0；

The two cameras are respectively calibrated in a binocular mode to obtain respective internal parameter matrixes K1 and K2 of the left camera and the right camera and an external parameter matrix M between the internal parameter matrixes and the external parameter matrixes, the focal length f of the cameras is obtained from the internal parameter matrixes, the included angle alpha and the base length L are obtained from the external parameter matrixes, and a conversion matrix M from a local coordinate system of the two cameras to a coordinate system of a binocular system can be further obtained according to the alpha and the L_1to0、M_2to0；

S424, obtaining coordinates of the light spots in the left image and the right image through image matching, and setting the coordinates as p_a、p_b(ii) a Obtaining the coordinate P of the light spot in the negative film through conversion_a、P_bFrom which x1, x2 are derived; wherein

S425, converting the matrix M_1to0、M_2to0The coordinates of A, B, C1 and C2 are converted from the respective local coordinate systems to be represented under a binocular system coordinate system; and the coordinates of P are solved by combining the linear equations of AC1 and BC 2.

As a further improvement of the cable type position parameter measuring method for the railway network inspection robot, the camera is an industrial camera.

As a further improvement of the cable type position parameter measuring method for the inspection robot of the railway network according to the present invention, the transformation matrix in step S423 is synthesized by a rotation matrix and a translation matrix, that is, M is T · R, where T: translating the matrix; r: a rotation matrix with units orthogonal.

As a further improvement of the cable type position parameter measuring method for the railway network inspection robot of the present invention, in step S425, the linear equations AC1 and BC2 are respectively:

in summary, compared with the prior art, the invention has the beneficial effects that: when the device is used for measurement, the word line laser is firstly turned on, light spots of the word line laser are irradiated on the cable, and the light spots on the cable are in a dot shape. The left camera and the right camera simultaneously take a picture, and the picture has light spots of cables and other light spots, such as carrier cables, guide rods, slings and the like. At this point processing is performed by an image pre-processing algorithm. The points of small noise are first denoised using morphological denoising. And then performing algorithm identification by using an image identification algorithm. Therefore, the position parameters of the cable can be measured efficiently and accurately; can greatly reduce the labor cost, and is safe and reliable.

Drawings

FIG. 1 is a schematic view of a measurement process according to the present invention.

Fig. 2 is one of the principle diagrams of the present invention.

Fig. 3 is a second schematic diagram of the present invention.

Detailed Description

The above and further features and advantages of the present invention are described in more detail below with reference to the accompanying drawings.

Preferred embodiments of the present invention are described below with reference to the accompanying drawings. It should be understood by those skilled in the art that these embodiments are only for explaining the technical principle of the present invention, and do not limit the scope of the present invention.

It should be noted that in the description of the present invention, the terms of direction or positional relationship indicated by the terms "upper", "lower", "left", "right", "inner", "outer", etc. are based on the directions or positional relationships shown in the drawings, which are only for convenience of description, and do not indicate or imply that the device or element must have a specific orientation, be constructed in a specific orientation, and be operated, and thus, should not be construed as limiting the present invention.

Furthermore, it should be noted that, in the description of the present invention, unless otherwise explicitly specified or limited, the terms "mounted," "connected," and "connected" are to be construed broadly, and may be, for example, fixedly connected, detachably connected, or integrally connected; can be mechanically or electrically connected; they may be connected directly or indirectly through intervening media, or they may be interconnected between two elements. The specific meanings of the above terms in the present invention can be understood by those skilled in the art according to specific situations.

As shown in fig. 1-2, a method for measuring a position parameter of a long-distance cable, is characterized in that: cameras are respectively arranged on two sides of a car body of the railway power network inspection robot, the connecting line of the two cameras is perpendicular to a track, the distance between the two cameras is fixed, an included angle is formed between the axis of a camera lens of each camera and the plane of the track, a line laser is arranged on the car body between the connecting lines of the two cameras, and two camera mirrors and the line laser are arranged on the same plane; the cable type position parameter measuring method at least comprises the following steps:

s1, controlling a line laser to emit laser to irradiate the cable;

s2, controlling the left camera and the right camera to shoot the image pictures of the cable at the same time;

s3, preprocessing the image and removing noise;

s4, carrying out image recognition on the image preprocessed in the step S3 to obtain the cable light spot position;

and S5, substituting the spot coordinates into a formula, and calculating data to be measured.

The method also comprises a step S6 of sending the data calculated in the step S5 to the robot upper computer through a communication protocol. The robot upper computer is communicated with the lower computer, so that the starting, the stopping and the rotating speed of a motor are controlled, the laser brightness is adjusted, and data and the like are interacted with various sensors (an obstacle avoidance radar, a GPS positioning sensor, an inclination sensor and the like); on the other hand, the upper computer stores the measurement data returned by various sensors in a chart form on a local hard disk so as to be referred by a user.

In the invention, a vehicle-mounted light supplementing light source is arranged on the vehicle body. Under the assistance of the on-line laser and the vehicle-mounted supplementary lighting, the measuring method can cover different illumination environments such as dusk, night and the like.

In the invention, in step S3, a morphological denoising method is used to perform denoising processing on the points with small noise.

The image recognition described in step S4 in the present invention includes the steps of:

s41, performing Gaussian smoothing operation on the image, then performing binarization, segmenting the binarized image, labeling a connected domain, and determining a legal cable coordinate according to the connected domain;

and S42, comparing the cable coordinates of the current frame with the cable coordinates of the previous n frames respectively, if the gradient of the coordinate change is within a given interval range, determining the cable coordinates as normal cable coordinates, transmitting the normal cable coordinates to a solver to perform space coordinate solution, and determining the solution value as the light spot coordinates.

The gradient of coordinate change in the invention is the coordinate difference value of two adjacent frames.

In the invention, Gaussian smoothing, binarization and the like are common image processing methods.

Wherein the step S41 specifically includes the following steps:

s411, if the obtained connected domains are proper in number and the area of each connected domain is within a given interval, calculating the center of each connected domain to serve as a cable coordinate, if the cable coordinate is within the given interval range, comparing the areas of the connected domains of the left view and the right view, and if the area difference is less than a given threshold value, determining that the cable coordinate is legal;

s412, if the number of the obtained connected domains is too small, changing the size of a Gaussian kernel and a binarization threshold value, then performing Gaussian smoothing and binarization on the original image again, and labeling the connected domains on the binarized image; executing step S411;

s412, if the number of the connected domains obtained at the moment is too large, performing self-adaptive binarization operation on the smoothed image, performing straight line detection, calculating the slope of each line segment, discarding the line segments of which the slopes are not within a given range, eliminating outlier line segments through an isolated forest algorithm, clustering the remaining line segments to obtain a plurality of line clusters, calculating the dispersion degree of each line cluster, if the dispersion degree is within an acceptable range, using the clustering centers as the centers of the respective line clusters, otherwise discarding the line segments far away from the clustering centers, and repeating the steps until the dispersion degree is within the acceptable range; the cluster center can be regarded as the center of the cable, the cluster discrete degree is converted into the radius of the cable according to a predefined rule, the positions of the candidate connected domains and the cable are compared, if the connected domains are located in the range of the cable and the area of each connected domain is within a given interval, the connected domains are light spots formed on the cable by the laser, and step S411 is executed.

The coordinate solving process in step S42 in the present invention includes:

s420, parameter setting

Setting the centers of the photosensitive films of the left camera and the right camera as O1 and O2; the focal length of the camera is f; the focal points of the left camera and the right camera are C1 and C2; the optical axes of the left camera and the right camera are respectively a connecting line of O1 and C1 and a connecting line of O2 and C2; the included angle between the optical axis and the plumb line is alpha; the distance between O1O 2 is the base length L; the midpoint of O1O 2 is O0;

the point to be measured in the space is P, and the coordinate of the point to be measured P under the binocular coordinate system is (x, y); the imaging points of the point P in the left camera negative and the right camera negative are A, B respectively, the distance from the imaging point A to the optical center O1 is x1, and the distance from the imaging point B to the optical center O2 is x 2;

s421, constructing a binocular system coordinate system;

constructing a binocular system coordinate system by taking O0 as an origin, O1O 2 as an x axis, wherein a vertical line is a y axis, the upward direction is a positive direction of the y axis, and the point from O0 to O2 is the positive direction of the x axis;

s422, constructing local coordinate systems of the left camera and the right camera;

respectively constructing local coordinate systems of the left camera and the right camera by taking O1 and O2 as original points, taking respective optical axes as y axes and taking the right side of the negative film as the positive direction of the x axis;

s423, constructing a transformation matrix M from the local coordinate system of each of the two cameras to the coordinate system of the binocular system_1to0、M_2to0；

The two cameras are respectively calibrated in a binocular mode to obtain respective internal parameter matrixes K1 and K2 of the left camera and the right camera and an external parameter matrix M between the internal parameter matrixes and the external parameter matrixes, the focal length f of the cameras is obtained from the internal parameter matrixes, the included angle alpha and the base length L are obtained from the external parameter matrixes, and a conversion matrix M from a local coordinate system of the two cameras to a coordinate system of a binocular system can be further obtained according to the alpha and the L_1to0、M_2to0；

S424, obtaining coordinates of the light spots in the left image and the right image through image matching, and setting the coordinates as p_a、p_b(ii) a Obtaining the coordinate P of the light spot in the negative film through conversion_a、P_bFrom which x1, x2 are derived; wherein

S425, converting the matrix M_1to0、M_2to0The coordinates of A, B, C1 and C2 are converted from the respective local coordinate systems to be represented under a binocular system coordinate system; and the coordinates of P are solved by combining the linear equations of AC1 and BC 2.

The binocular calibration in the invention can be referred to Z.Zhang. A Flexible New Technique for Camera calibration. technical Report MSRTR-98-71,1998.

The conversion matrix in the invention is synthesized by a rotation matrix and a translation matrix, namely M is T.R, wherein T: translating the matrix; r: a rotation matrix with units orthogonal. T is related to the base length L and R is related to the included angle alpha. Since the expression form and properties of the translation and rotation matrix are the basic contents of the projection geometry, the details are not repeated here.

In the invention p_a、p_bPa, Pb are both column vectors, and x1, x2 are both elements in the vector, i.e. the coordinates of the spot in the image and its corresponding coordinates on the film are both given in the form of a vector. The vector to be solved can be obtained through matrix multiplication, and naturally, each element in the vector can be obtained.

The straight line equations of AC1 and BC2 in the invention are respectively:

in the invention, the equations are solved simultaneously, and the coordinate of P can be solved.

The foregoing shows and describes the general principles and features of the present invention, together with the advantages thereof. It will be understood by those skilled in the art that the present invention is not limited to the embodiments described above, which are described in the specification and illustrated only to illustrate the principle of the present invention, but that various changes and modifications may be made therein without departing from the spirit and scope of the present invention, which fall within the scope of the invention as claimed. The scope of the invention is defined by the appended claims and equivalents thereof.