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CN-116823964-B - Physical parameter model of camera-galvanometer variable sight system and calibration method thereof

CN116823964BCN 116823964 BCN116823964 BCN 116823964BCN-116823964-B

Abstract

The invention provides a physical parameter model of a camera-galvanometer variable vision system and a calibration method thereof, wherein a complete geometric process of imaging in a camera after space points are deflected by a galvanometer is modeled, the deflection and imaging processes are parameterized, and the variable vision system parameters comprise two-dimensional scanning galvanometer parameters, camera parameters, relative installation pose parameters of the camera and the two-dimensional scanning galvanometer and pose parameters of the variable vision system under a world coordinate system, so that the specific mathematical relationship between the space points and the imaging points of the variable vision system under any deflection vision is described, and the modeling and calibration of the camera-galvanometer variable vision imaging system are completed by the calibration method. The invention enables the imaging process of the variable vision imaging system under any vision to be obtained through model parameter solving, so that the variable vision imaging system can be used in quantitative vision application, the model physical meaning is clear, the parameters are concise and clear, the calibration process is simple and convenient to operate, and the calibration result has high reliability and strong stability.

Inventors

  • ZHANG LIYAN
  • HAN ZIDONG

Assignees

  • 南京航空航天大学

Dates

Publication Date
20260505
Application Date
20230621

Claims (9)

  1. 1. A physical parameter model of a camera-galvanometer variable sight imaging system is characterized in that parameterization modeling is carried out on a complete optical process that space points are imaged in a camera after being deflected by a two-dimensional scanning galvanometer, parameters in the parameterization model are clear physical significance, the parameterization model comprises two-dimensional scanning galvanometer parameters describing light deflection and reflection of the two-dimensional scanning galvanometer, imaging parameters of a camera and a lens, relative installation pose parameters between the camera and the two-dimensional scanning galvanometer and pose parameters of the two-dimensional scanning galvanometer in a world coordinate system, the parameterization model converts the space points into the two-dimensional scanning galvanometer coordinate system through the pose parameters of the two-dimensional scanning galvanometer in the world coordinate system, three-dimensional points in the two-dimensional scanning galvanometer coordinate system obtain virtual mirror image points after two total reflections of the two-dimensional scanning galvanometer through the two-dimensional scanning galvanometer parameters, the virtual mirror image points are converted into the camera coordinate system through relative installation pose parameters between the camera and the two-dimensional scanning galvanometer, and finally pixels of imaging image forming image points are obtained through the imaging parameters of the camera and the lens, and the parameterization model is specifically that the space points are converted into two-dimensional scanning galvanometer coordinate system through deflection angles in the two axes Input control quantity with two-dimensional scanning galvanometer Parameterizing the relation between the two components to establish According to the distance e between the rotation axes of two reflecting mirrors in the galvanometer and a given galvanometer deflection control amount Corresponding deflection angle Calculating to obtain the deflection control quantity of the vibrating mirror The corresponding galvanometer deflection transformation matrix H.
  2. 2. The camera-galvanometer variable line-of-sight imaging system of claim 1, wherein the functional relationship Input control quantity of two-dimensional scanning galvanometer Polynomial approximation method for deflection angle of vibrating mirror Parameterization is performed.
  3. 3. The method for transforming a physical parameter model of a camera-galvanometer variable line-of-sight imaging system as set forth in claim 1, wherein the galvanometer deflection transformation matrix H is used for describing a transformation process of obtaining virtual mirror image points by sequentially reflecting points in a two-dimensional scanning galvanometer coordinate system through a lens-2 and a lens-1 in the two-dimensional scanning galvanometer.
  4. 4. The method for generating a physical parameter model of a camera-galvanometer variable line-of-sight imaging system as set forth in claim 1, wherein the relative mounting pose parameters between the camera and the two-dimensional scanning galvanometer establish respective Cartesian coordinate systems for the camera and the scanning galvanometer, respectively, through a rigid body transformation matrix The transformation relation between the two coordinate systems is described, the transformation of the three-dimensional point from the two-dimensional scanning galvanometer coordinate system to the camera coordinate system is represented, and the parameterization of the assembly pose between the camera and the two-dimensional scanning galvanometer is realized.
  5. 5. The method for generating a physical parameter model of a camera-galvanometer variable line-of-sight imaging system as set forth in claim 1, wherein the pose parameters of the two-dimensional scanning galvanometer in world coordinate system are transformed by a rigid body transformation matrix And establishing a transformation relation between the two-dimensional scanning galvanometer coordinate system and the world coordinate system, and representing transformation of the three-dimensional points from the world coordinate system to the two-dimensional scanning galvanometer coordinate system.
  6. 6. A method of calibrating a physical parameter model for a camera-galvanometer variable line-of-sight imaging system of claim 1, comprising the operations of: 1) The calibration of the two-dimensional scanning galvanometer parameters, the camera and the lens parameters is completed; 2) Calibrating the installation pose parameters of the camera and the galvanometer and the pose parameters of a two-dimensional scanning galvanometer coordinate system in a world coordinate system; 3) And carrying out nonlinear optimization on all parameters in a physical parameter model of the variable line-of-sight imaging system.
  7. 7. The method for calibrating a physical parameter model of a camera-galvanometer variable-line-of-sight imaging system according to claim 6, wherein in step 2), control parameters are sequentially input to the variable-line-of-sight imaging system by calibrating the mounting pose parameters of the camera and the galvanometer and the pose parameters of a two-dimensional scanning galvanometer coordinate system in a world coordinate system Calculating the deflection control amount of each given vibrating mirror Coordinate system transformation matrix from world coordinate system under corresponding imaging vision line to camera imaging coordinate system According to ; Obtaining a linear equation set formed by M equations corresponding to M sightlines, and obtaining a rigid body transformation matrix by solving the linear equation set Rigid body transformation matrix 。
  8. 8. The method for calibrating a physical parameter model of a camera-galvanometer variable line-of-sight imaging system as set forth in claim 7, wherein the variable line-of-sight imaging system is characterized by a controlled amount of galvanometer deflection Coordinate system transformation matrix from world coordinate system to camera imaging coordinate system under corresponding imaging vision According to the parameters of the camera and the lens, more than 4 three-dimensional points with known coordinates in a world coordinate system and the deflection control quantity of each three-dimensional point with known coordinates in a vibrating mirror And obtaining pixel point coordinates on an image under the imaging sight of the corresponding camera.
  9. 9. The method for calibrating a physical parameter model of a camera-galvanometer variable line-of-sight imaging system according to claim 6, wherein in the step 3), the nonlinear optimization process reprojects spatial points onto an image plane of the variable line-of-sight imaging system through the physical parameter model of the variable line-of-sight imaging system to obtain reprojected pixel coordinates, and optimizes all parameters in the physical parameter model of the variable line-of-sight imaging system by minimizing errors between the reprojected pixel coordinates and the acquired pixel coordinates to obtain final variable line-of-sight imaging system parameters.

Description

Physical parameter model of camera-galvanometer variable sight system and calibration method thereof Technical Field The invention relates to the technical field of machine vision, in particular to a physical parameter model of a camera-galvanometer variable vision imaging system and a calibration method thereof. Background The two-dimensional scanning galvanometer is a vector scanning device which drives two optical lenses to rapidly deflect around respective rotating shafts by two special swinging motors, and deflection of emergent light in the two-dimensional direction can be realized by changing the deflection angles of the two rotating shafts. Along with the continuous development of the two-dimensional scanning galvanometer manufacturing technology, the positioning precision, the repetition precision and the scanning speed of the galvanometer are greatly improved, and the two-dimensional scanning galvanometer is widely applied in a plurality of fields. For example, changing the outgoing direction of an incident laser beam by high-speed axial deflection of two optical lenses has been widely used in laser marking, laser processing, laser marking, laser medical cosmetology, and the like. In recent years, two-dimensional scanning galvanometers have also been used in conjunction with vision imaging systems to change the line of sight of the imaging system and expand the field of view of the camera. For example Liu Chenyi (Liu Chenyi. Large field of view small target visual tracking technology research [ university of major science and technology paper ]. University of chinese science and technology 2019) studied the tracking technology of a galvanometer-camera combined system in a large field of view, zhou Kai (Zhou Kai) studied the long-distance large field of view iris recognition technology based on galvanometer scanning [ university of major science and technology paper ]. University of western electronics science and technology 2019) applied galvanometer-camera systems to high resolution imaging of local small areas. In these studies, the two-dimensional scanning galvanometer is only used for changing the imaging area of the camera when shooting each time, and no quantitative relation between the three-dimensional scene and each point on the imaging plane of the camera under different galvanometer deflection angles is established. in various applications related to three-dimensional vision, the establishment of a three-dimensional imaging model of an imaging system is an indispensable premise and foundation. However, for a camera-galvanometer combined variable-line-of-sight imaging system, the two-dimensional scanning galvanometer is doped with a plurality of uncertain factors such as the position and direction of incident light, the precise deflection angle, the distance between two axes of the galvanometer and the like, so that the reflection process is difficult to model accurately, and unlike a laser-galvanometer system which only has one laser beam incident on the central rotating shaft of the first optical lens, each pixel on a two-dimensional image plane corresponds to one principal ray in the camera-galvanometer imaging system, the principal ray is converged to the optical center of the camera through a group of lenses by reflection of the two galvanometers and imaged at the corresponding pixel position of the image plane. therefore, the imaging position of the three-dimensional scene on the imaging plane is related to imaging parameters including nonlinear distortion of the three-dimensional scene and the camera, and is also related to two deflection angles of the galvanometer, and the factors are integrated together, so that the difficulty of establishing an accurate working model of the camera-galvanometer variable-line-of-sight imaging system is great. At present Han Zidong et al (a three-dimensional imaging model of a variable vision line system combining a camera and a galvanometer and a calibration method thereof, china patent, CN 202110469560.1) propose a three-dimensional imaging model facing the variable vision line imaging system and a calibration method thereof, the proposed model of the camera-galvanometer variable vision line imaging system is a neural network black box model, and the model calibration is realized by means of a data driving method, so that a large amount of data are required to be collected for calibration, the calibration difficulty is high, the model is not visual, and the parameters in the model lack definite physical significance. Zhang Liyan et al (China patent application No. 202211692983.0) propose an equivalent multiview system model of a variable line-of-sight imaging system and a calibration method thereof, wherein the model is characterized in that the line-of-sight direction of the variable line-of-sight system is discretely sampled and the sampled line of sight is respectively calibrated, and the model is simple and convenient in calibratio