Technology And Application Of 3D Contour Reconstruction Based On Raster Projection

The grating projection is a kind of three-dimensional topography reconstruction technology,which has the characteristics of fast measurement speed,large measurement range,high measurement precision and high data acquisition.In industrial inspection,quality control,welding robot vision,reverse engineering,virtual reality,Digitalization of cultural relics and face recognition and many other fields have a wide range of applications.Based on the basic principle of three-dimensional contour reconstruction of grating stripes based on phase shift method,this paper studies the techniques of grating solution,phase unwrapping and system calibration,and applies the technology to the LinuxCNC system.Contour welding simulation.The main contents and work of the thesis include the following aspects:(1)The main research contents of the three-dimensional measurement technology and the subject are summarized.The mathematical model of the three-dimensional measurement system of the grating projection is analyzed,and the phase shift method is applied to the stripe image.Then,the phase unwrapping algorithm based on discrete cosine transform is studied,and the time phase unwrapping algorithm based on multi-frequency heterodyne principle and fitting negative exponent is realized,and the real object is verified experimentally.(2)In the aspect of camera calibration,the camera model is established.The plane calibration method between traditional calibration and self-calibration is realized according to the camera parameters.The camera calibration based on Zhang zhen you's principle,and the intermal parameters and distortion parameters of the camera are solved quickly and effectively.In the projector calibration,a projector model was established,and the projector was calibrated using the plane calibration method and the image-based coherence matrix method.Visual Studio 2013 as the development tool,through the Microsoft basic class library MFC interface development,combined with OpenCV image processing library to complete the system calibration software design,and finally through the calibration experiment to get the camera and projector internal and external parameters.(3)Completed the entire system of experimental environment structures.The three-dimensional contour reconstruction system of grating projection is developed by using Matlab GUI interface.It mainly includes grating striping generation module,camera acquisition module,image preprocessing module,phase main value solving module,phase expansion module,system calibration module,3D point cloud Processing module and other functions.through the combination of hardware and software,to achieve the real object of the three-dimensional surface reconstruction.Finally,the accuracy of the system is analyzed according to the plane measurement results.(4)It is proposed to apply grating projection technology to workpiece arc welding.The contour information of the workpiece is extracted,the edge contour coordinate information is obtained,the coordinate information is combined with the height information in the three-dimensional reconstruction,the G code program is generated according to the coordinate information of the two,and then the G code data is imported into the LinuxCNC system,And finally in the system to achieve the automatic contour welding simulation of the workpiece.