Research On 3D Reconstruction Of The Main Screw Hole In Nuclear Reactor Pressure Vessel Based On Binocular Vision

As a branch of machine vision technology,binocular vision has become a research hotspot and been widely used in various fields because of its low cost,simplicity and convenience,strong practicability,etc.In addition,due to the continuous refinement of the detection of the main screw hole in the pressure vesselof nuclear reactor,it can be further studied to realize the 3D scanning and defect judgment of the main screw hole.On the basis of binocular stereo vision technology,this paper has been studied the 3D reconstruction technology of the inner surface of the main screw hole in the pressure vessel of nuclear reactor,and compelets its 3D reconstruction.The main research contents and work are as follows:(1)Studying on the principle of binocular stereo vision.According to the environment and size of the reconstruction target,the selection of the camera and the design of the image acquisition device are completed.On this basis,the hardware platform is built to complete the image acquisition of the reconstruction target.(2)Removing noise by image preprocessing and obtaining high-quality images.Several denoising algorithms are introduced to smooth the image,and then sharpen it to offset the blurring effect.(3)Studying on the camera calibration technology.By using Zhang Zhengyou plane template calibration method,the calibration of the binocular camera is completed,and the internal parameters,external parameters and distortion coefficient of the camera are calculated,which is well ready for the subsequent processing.(4)In the aspect of image stereo matching,region-based and feature-based matching methods are studied.On the basis of the region-based matching method,the comparison experiment of the three algorithms of SSD,SAD,NCC is carried out,and the disparity map is obtained.This paper focuses on the SIFT algorithm,and using SIFT features for matching,using random sampling consistency algorithm for eliminating mismatches.And the feasibility of the algorithm is verified by the experiment.(5)In the aspect of 3D reconstruction.The 3D coordinate calculation of characteristic points for parallel binocular system is calculated,and the 3D point cloud map is formed.Then the texture mapping technique is used to get the reconstruction results.Finally,the experiment is designed to complete the 3D reconstruction of the inner surface of the main screw hole in the pressure vessel of nuclear reactor.