A Three-dimensional Imaging Method And System Based On Spatiotemporal Correlation

Three-dimensional(3D)imaging of active stereo vision based on specular structure illumination is a non-contact,and fast optical 3D imaging and measurement method,which can be divided into two types of spatial correlation and temporal correlation,according to the principle of speckle correlation.The spatial correlation method only needs to project a speckle pattern,and the corresponding point matching is realized by the correlation of the gray change of the matching region.The method is suitable for the 3D imaging of dynamic scene,but it is easy to be affected by the measurement factors such as the surface curvature and the illumination change,leading to a low accuracy of 3D reconstruction.The temporal correlation methods need to project a series of temporal-varying speckle patterns,so as to establish a temporal series of gray distribution for each pixel,then use the temporal gray correlation is utilized to complete the corresponding point matching for high-precision 3D reconstruction,but the method does not apply to dynamic 3D imaging.This dissertation focus on 3D imaging based on speckle spatial correlation and temporal correlation.The main contents are as follows:1 ? The 3D reconstruction methods based on speckle spatial correlation and temporal correlation are achieved respectively.Some constraints of epipolar,parallax and grayscale are employed to achieve a fast integer-pixel corresponding point searching.Based on the integer-pixel corresponding point,the optimize algorithm of N-R iteration is employed by the spatial correlation method,and the curve fitting approach is used to by the temporal correlation method,to respectively obtain subpixel corresponding points to realize the 3D reconstruction with speckle correlation.2?This dissertation studies two kinds of speckle correlation based 3D imaging.One method uses the temporal correlation to determine the integer-pixel corresponding point of the whole speckle image sequence,and then uses the spatial correlation to determine the sub-pixel corresponding points of each frame speckle image.The series Sub-pixel corresponding points is averaged to get the accurate corresponding points.The other method derives a space-time correlation formula from the spatial and temporal correlation,which is regarded as the N-R function to be optimized to obtain the sub-pixel corresponding point.Two experimental system of 3D imaging with speckle space-time correlation were set up,which realized the high-precision threedimensional measurement of static objects and the high-speed 3D imaging of dynamic fan respectively.