Research On 3D Scanning Measurement Method Based On Double Projection System

Since the 21 st century,with the development of research on machine vision and image processing,3D scanning technology has made great progress.The structured light projection measurement technology,as a core component of 3D scanning,has been extensively used in advanced and intelligent manufacturing fields due to its advantages such as non-contact,high efficiency and precision,and rich point cloud information.However,this technology cannot be applied on some occasions,for example,precision measurement of large objects and extraction of complicated 3D geometric characteristic parameters.Based on the traditional monocular vision measurement system,this paper established a new dual-projection structured light system by extending the imaging range with the secondary light source to provide an effective solution for issues such as shadow and occlusion faced by the traditional structured light system.The research content is as follows:1.System calibration.This paper studied the key technologies affecting the 3D measurement of structured light and analyzed the imaging model of the camera and the phase-height mapping model of the measurement system in detail.It adopted the Zhang Zhengyou calibration method to calibrate the camera and obtained parameters related to the system height matrix by solving the linear equation.2.Image processing.For the processing of raster projection stripes,especially the separation of phase shift raster signal of the overlapping part in dual projection system,this paper put forward a new solution based on the traditional four-step phase shift method.Using gray level compensation between phase shift and raster,it calculated the phase by making reasonable timing arrangement to eliminate the interference signal in the overlapping part.For phase unwrapping,this paper compared the existing unwrapping algorithms from the aspect of time airspace and finally completed the phase unwrapping with the multi-frequency heterodyne method according to the actual situation.3.System design.In order to illustrate the advantages of the dual projection structure in solving the shadow and occlusion problems,this paper designed and built a dual projection system for structured light 3D measurement,wrote the matching measurement software based on the MFC framework in the Visual Studio integrated development environment to measure the 3D shape,and finally compared its result with that of the traditional single projection system.