Research And Application Of Phase Unwrapping Algorithm Based On The System Of Grating Projection 3D Measurement

With the continuous development and improvement of modern industry,optics,computer graphics and people's living standard,two-dimensional graphic design and traditional measurement methods can not meet the actual needs.3D profile measurement has become a hot topic that people are highly concerned about.As the most important part of the 3D profilometry system,the phase unwrapping algorithm is also one of the topics that people have paid much attention to at present.However,due to the image quality is low,the noise,the shadow area and the fringe breaks and other factors will occur in the actual measurement,resulting in phase unwrapping algorithm accuracy is not high,so the accuracy is not up to the requirements of the measurement system,the traditional phase unwrapping algorithm fails to meet real-time requirements in efficiency.Therefore,in order to achieve the two requirements of the measurement system for the accuracy and real-time of the phase unwrapping's results,this dissertation will focuses on the phase unwrapping algorithm and the CUDA(Computer Unified Device Architecture).First of all,according to the actual needs,several typical phase unwrapping algorithms are studied and analyzed in depth.For the problem that the quality of the phase unwrapping's results is not high and the error accumulating and propagating,this dissertation improves and optimizes the accuracy of the phase unwrapping algorithm from three aspects,such as image preprocessing,how to select the appropriate starting point of phase unwrapping,and marking and repairing the residual points.The image preprocessing includes the Gauss filter and the Otsu threshold segmentation,selecting the phase points of the center line of the light stripe as the appropriate starting point of the phase,and then using the residual point marker and the repair method to improve the accuracy and effectiveness of the phase unwrapping's results.Secondly,in order to improve the efficiency of the algorithm,this paper study the CUDA(Computer Unified Device Architecture)parallel computing method and combine it with the rhomboid phase unwrapping algorithm.A high quality parallel phase unwrapping algorithm is proposed to achieve the real-time measurement of the system.Finally,the accuracy and real-time performance of the proposed algorithm in this paper is verified by experiments of comparison and analysis with the existing phase unwrapping algorithm.Experimental results show that the improved high quality parallel phase unwrapping algorithm improves the computation efficiency and the phase quality,and achieves the requirements of real-time and high accuracy of the 3D measurement system.