Method for locating distorted center of wide-field lens

Abstract

The invention discloses a method for locating a distorted center of a wide-field lens. Firstly, imaging is carried out on a checkerboard target through a video camera, a distorted checkerboard target image is shot and obtained, feature points in the checkerboard target image are obtained, and usable feature points in the feature points are extracted. For each usable feature point, a quadrangle is built based on four feature points which are nearest to the usable feature point, and a geometric center of the quadrangle and a coordinate offset of the usable feature point are calculated. Then, coordinate offsets of all the usable feature points are adopted to construct a sample curved surface, and the position of a minimum value point of the sample curved surface is solved, namely, the position is a coordinate valve of the distorted center. According to the method, forms of targets can be diversified, operation is easy, an algorithm is simple, and the method can provide the effective distorted center for distortion correction.

Description

technical field [0001] The invention relates to the technical field of computer image processing, in particular to a distortion center positioning method of a wide field of view lens. Background technique [0002] With the development of computing science, computer vision is no longer limited to theoretical research, but has gradually entered into engineering applications, which need to deal with basic issues such as optical imaging, image quality, environmental lighting, and circuit noise. The actual lens does not satisfy the ideal pinhole imaging. During the projection process from the object space to the image plane, nonlinear distortion often exists, especially for wide field of view lenses, the distortion is even more serious. Therefore, distortion correction must be performed on the wide-field lens, and the most important step is to accurately locate the distortion center of the lens. [0003] There are two ways to express distortion, radial distortion and tangential ...

AI Technical Summary

Problems solved by technology

[0004] (1) Target calibration method, mainly by taking multiple target images at different spatial positions, extracting the pixel coordinates of the feature points on the image on the target, and then combining the real physical position relationship of the feature points on the target, using optimization iteration The internal parameter matrix and external parameter matrix of the camera are calculated by means of the method. The internal parameter matrix mainly includes the physical parameters of the camera, such as the distortion center and focal length, etc., and the external parameter matrix records the spatial position relationship between the target and the camera. This method is suitable for measuring In the case of distortion correction, its flexibility is limited by the equipment, and the calibration accuracy has a great relationship with the quality of the equipment

[0005] (2) Projection transformation method, mainly based on the principle that the projection of a straight line in space is still a straight line in the projection transformation theory, design the target so that the feature points are located on multiple straight lines, extract the target feature points on the distorted image, and use the projection constrained by the line Mathematical model, optimize and calculate the parameters of the distortion correction model. The distortion center is one of the optimization parameters. This method does not calculate all the internal and external parameters of the camera, so it can only be applied to non-measurement distortion correction. Its operation is simple but the calculation complexity is high , people have also proposed a variety of fast optimization methods

Images