A camera stereo calibration method using pentahedron

Abstract

The present invention relates to a method for stereoscopic camera calibration using a pentahedron, which is applied to a pentahedron calibration system. The pentahedron calibration system includes a pentahedron light box, a door panel is hinged at the bottom edge of the front opening of the pentahedron light box, a fixture is fixed to the inner wall of the door panel, and the other five inner walls of the pentahedron light box are all checkerboard targets, each checkerboard target is marked with dots, and the following steps are included: a camera installation step: the camera is fixedly installed inside the fixture, and then the door panel is swung to cover the front opening of the pentahedron light box; a coordinate acquisition step: the checkerboard corner point is selected as the origin, and the world coordinate values ​​and pixel coordinate values ​​of the first to nth dots are photographed in order of first shooting the front, then the left, top, right, and bottom. The technical solution of the present invention can complete the calibration of the camera by only taking one picture under different fields of view, thereby improving the efficiency of camera calibration.

Description

Technical Field

[0001] The present invention relates to the technical field of camera stereo calibration, and in particular to a camera stereo calibration method using a pentahedron. Background Art

[0002] In the image measurement process and machine vision applications, in order to determine the relationship between the three-dimensional geometric position of a point on the surface of a spatial object and its corresponding point in the image, a geometric model of camera imaging must be established. These geometric model parameters are camera parameters. Under most conditions, these parameters (intrinsic parameters, external parameters, distortion parameters) must be obtained through experiments and calculations. The process of solving the parameters is called camera calibration (or camera calibration).

[0003] Whether in image measurement or machine vision applications, camera parameter calibration is a critical step. The accuracy of the calibration results and the stability of the algorithm directly affect the accuracy of the camera's work results. However, in different field of view situations, multiple pictures need to be taken to cover the full frame of the camera for calibration, which is extremely inconvenient. Summary of the invention

[0004] The purpose of the present invention is to provide a method for stereo calibration of a camera using a pentahedron. The present invention can complete the calibration of the camera by only taking one picture under different fields of view, thereby improving the efficiency of camera calibration.

[0005] To achieve the above object, the present invention provides the following technical solutions:

[0006] A camera stereo calibration method using a pentahedron is applied to a pentahedron calibration system. The pentahedron calibration system includes a pentahedron light box. A door panel is hinged on the bottom edge of the front opening of the pentahedron light box. A fixture is fixed to the inner wall of the door panel. The other five inner walls of the pentahedron light box are all checkerboard targets. Each checkerboard target is marked with dots. The method includes the following steps:

[0007] Camera installation steps: fix the camera inside the fixture, and then swing the door panel to cover the front opening of the pentahedral light box;

[0008] Coordinate acquisition steps: select the corner point of the chessboard as the origin, shoot the front first, then the left, top, right, and bottom in sequence, and obtain the world coordinate values ​​and pixel coordinate values ​​of the first to nth dots in sequence.

[0009] The world coordinate value of the i-th point is:

[0010] The pixel coordinate value of the i-th point is:

[0011] Equation writing steps: List the transformation equations from the world coordinates of the first point to the nth point to the image coordinates as follows:

[0012]

[0013] (i=1、2、3……、n)

[0014] After deformation:

[0015]

[0016]

[0017] (i=1、2、3……、n)

[0018] Solution steps: By combining the equations corresponding to the 1st to the nth points, and using iterative approximation to find the parameter matrix The approximate values ​​of each parameter are used to obtain the intrinsic parameters of the camera.

[0019] Specifically, the pentahedron calibration system includes a computer host and a display, and the computer host and the display are both electrically connected to the camera.

[0020] Specifically, the checkerboards on the five inner walls of the pentahedral light box are black and white checkerboards.

[0021] Specifically, the five inner walls of the pentahedral light box are all rectangular.

[0022] Specifically, the camera's field of view includes five inner wall checkerboard targets of the pentahedral light box.

[0023] Compared with the prior art, the present invention has the following beneficial effects:

[0024] The camera sequentially identifies the world coordinate values ​​and pixel coordinate values ​​of each dot on the five inner wall checkerboards of the pentahedral light box, so that the camera's matrix equation that converts world coordinate values ​​into pixel coordinate values ​​can be quickly established, and then the parameter matrix (i.e., camera internal parameters) can be calculated.

[0025] The technical solution of the present invention can complete the calibration of the camera under different fields of view by only taking one picture, thereby improving the efficiency of the camera calibration and having great significance for the single-frame calibration of the camera calibration. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0027] Figure 1 Front view of the pentahedron calibration system;

[0028] Figure 2 Side view of the pentahedron calibration system;

[0029] Figure 3 It is the side view of the opening of the pentahedral light box;

[0030] Figure 4 An interior view of the pentahedral light box. DETAILED DESCRIPTION

[0031] The technical solutions in the embodiments of the present invention will be described clearly and completely below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments.

[0032] See Figures 1 to 4 A camera stereo calibration method using a pentahedron is applied to a pentahedron calibration system. The pentahedron calibration system includes a pentahedron light box. A door panel is hinged on the bottom edge of the front opening of the pentahedron light box. A fixture is fixed to the inner wall of the door panel. The other five inner walls of the pentahedron light box are all checkerboard targets. Each checkerboard target is marked with dots. The method includes the following steps:

[0033] Camera installation steps: fix the camera inside the fixture, and then swing the door panel to cover the front opening of the pentahedral light box;

[0034] Coordinate acquisition steps: select the corner point of the chessboard as the origin, shoot the front first, then the left, top, right, and bottom in sequence, and obtain the world coordinate values ​​and pixel coordinate values ​​of the 1st to nth points in sequence.

[0035] The world coordinate value of the i-th point is:

[0036] The pixel coordinate value of the i-th point is:

[0037] Equation writing steps: List the transformation equations from the world coordinates of the 1st point to the nth point to the image coordinates as follows:

[0038]

[0039] (i=1、2、3……、n)

[0040] After deformation:

[0041]

[0042]

[0043] (i=1、2、3……、n)

[0044] Solution steps: By combining the equations corresponding to the 1st to the nth points, and using iterative approximation to find the parameter matrix The approximate values ​​of each parameter are used to obtain the intrinsic parameters of the camera.

[0045] Specifically, the pentahedron calibration system includes a computer host and a display, and the computer host and the display are both electrically connected to the camera.

[0046] Specifically, the checkerboards on the five inner walls of the pentahedral light box are black and white checkerboards.

[0047] Specifically, the five inner walls of the pentahedral light box are all rectangular.

[0048] Specifically, the camera's field of view includes five inner wall checkerboard targets of the pentahedral light box.

[0049] The working principle of the camera stereo calibration method using a pentahedron in the present invention is as follows:

[0050] The camera sequentially identifies the world coordinate values ​​and pixel coordinate values ​​of each dot on the five inner wall checkerboards of the pentahedral light box, so that the camera's matrix equation that converts world coordinate values ​​into pixel coordinate values ​​can be quickly established, and then the parameter matrix (i.e., camera internal parameters) can be calculated.

[0051] The technical solution of the present invention can complete the calibration of the camera under different fields of view by only taking one picture, thereby improving the efficiency of the camera calibration and having great significance for the single-frame calibration of the camera calibration.

[0052] The above are only preferred embodiments of the present invention, and are not intended to limit the present invention in any form. Although the present invention has been disclosed as above in the form of preferred embodiments, it is not intended to limit the present invention. Any technical personnel in the field can make some changes or modify the technical contents disclosed above into equivalent embodiments without departing from the scope of the technical solution of the present invention. However, any brief modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solution of the present invention are still within the scope of the technical solution of the present invention.

Claims

1. A method for stereoscopic calibration of a camera using a pentahedron, which is applied to a pentahedron calibration system. The pentahedron calibration system includes a pentahedron light box, which is a rectangular box. The five inner walls of the pentahedron light box are all rectangular. A door panel is hinged on the bottom edge of the front opening of the pentahedron light box. A fixture is fixed to the inner wall of the door panel. The remaining five inner walls of the pentahedron light box are all checkerboard targets. Each checkerboard target is marked with dots. The checkerboards of the five inner walls of the pentahedron light box are black and white checkerboards. The pentahedron calibration system includes a computer host and a display. The computer host and the display are electrically connected to the camera. The field of view of the camera includes the five inner wall checkerboard targets of the pentahedron light box. It is characterized in that The following steps are involved: Camera installation steps: fix the camera inside the fixture, and then swing the door panel to cover the front opening of the pentahedral light box; Coordinate acquisition steps: select the corner point of the chessboard as the origin, shoot the front first, then the left, top, right, and bottom in sequence, and obtain the world coordinate values ​​and pixel coordinate values ​​of the first to nth dots in sequence. The world coordinate value of the i-th point is: The pixel coordinate value of the i-th point is: Equation writing steps: List the transformation equations from the world coordinates of the first point to the nth point to the image coordinates as follows: (i=1, 2, 3, ..., n) After deformation: (i=1, 2, 3, ..., n) Solution steps: By combining the equations corresponding to the 1st to the nth points, and using iterative approximation to find the parameter matrix The approximate values ​​of each parameter are used to obtain the intrinsic parameters of the camera.

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