A Research On Zoom Binocular Ranging Algorithms Based On Focal-Length Correction

Binocular disparity ranging is one of the important branches of computer vision.At present,many frontier computer technologies,such as VR,AR,AI and so on,are inseparable from the support of binocular ranging technology.However,the current traditional binocular disparity ranging technology requires that the focal length of two cameras should be consistent or approximately identical.To control the focal length of two cameras accurately,fixed-focus cameras must be used as ranging equipment.Zoom cameras can not meet the requirements,which brings great inconvenience to the application and promotion of binocular disparity ranging.Aiming at the limitation of binocular disparity ranging on focal length,starting from its basic principle,this paper deeply explores the role of focal length in binocular disparity ranging,analyses the causes of the consistency limitation of left and right camera focal length in binocular disparity ranging,conceives the idea of improving it,and puts forward Focal-Length Correction zoom ranging algorithm,the Chinese name is zoom based on focal length correction.Ranging algorithm,referred to as FLC ranging algorithm.According to the principle of three-dimensional space transformation,the FLC ranging algorithm corrects the focal length by selecting three groups of corresponding points on the left and right images,deducing the space transformation matrix of the left and right images,extracting the zoom factor between the left and right images,and then using the zoom factor as the benchmark,enlarging and clipping the left and right images to reduce the difference of the focal length between the left and right images.Of course,because of operational errors and other factors,if FLC ranging algorithm is only operated once,its effect is not ideal.Therefore,FLC ranging algorithm is designed to improve the effect of focal length correction and obtain new left and right images with similar focal length after repeated iterative focal length correction.After many iterations correction by FLC algorithm,the focal length of left and right images can be approximately the same,which meets the requirements of binocular disparity ranging.Using FLC ranging algorithm,binocular parallax ranging can be implemented by two cameras with arbitrary focal length.Whether fixed-focus or zoom cameras,it is not necessary to pay attention to whether the focal length is consistent or approximately identical.This paper expounds the influence of focal length on camera imaging from the principle of camera imaging,expounds the rationality of using zoom factor of three-dimensional space transformation to perform focal length correction,introduces in detail the methods and steps of obtaining spatial zoom factor,and demonstrates the influence of focal length correction effect on ranging error by way of formula deduction.In this paper,the FLC ranging algorithm is implemented systematically,and the original image is corrected by the system.After several iterations of focal length correction,the new image with a focus difference of less than 1% is obtained successfully.At the same time,the error between the camera calibration baseline distance and the actual baseline distance is less than 0.028 mm,which proves the effectiveness of the FLC algorithm.Moreover,this study proves by mathematical formulas that the percentage difference between the results of the left and right focal lengths and the results of the left and right focal lengths is less than that of the left and right focal lengths when the baseline of the left and right cameras is fixed.That is to say,when the difference between the left and right focal lengths is less than 1% after many iterations,the results of the distance measurement are the same as those of the left and right focal lengths.The difference must be less than 1%,which proves the validity and feasibility of FLC ranging algorithm in zoom camera ranging.