Research On Handheld 3D Scanning Technology Without Marked Point Based On Digital Fringe Projection

Three-dimensional scanning technology is a technology that relates to optical, mechanical, electrical, computer science and other aspects of knowledge. It can realize the fast digital 3D modeling of objects, and it is widely used in many respects such as reverse engineering, digital manufacturing, virtual reality, product testing, heritage conservation and so on. Among them, the 3D scanning technology of grating projection is getting more and more attention because of its advantages of accuracy and speed. At present, the products of North America and Europe have high market share, but these three dimensional scanning equipment is expensive for small and medium enterprises. Therefore, we try to develop a 3D scanning equipment that is low-cost, fast, compact and easy to use, based on the phase calculation, multi-frequency heterodyne principle of phase package calculation, phase error correction, the camera parameter calibration, phase- height calibration and scale space key point detection technique. The research content of the whole paper is as follows:The camera calibration technique based on planar ring array target was studied. Due to the gray mutation at corners of Zhang zhengyou black-and-white checkerboard target, the checkerboard cannot be used for the phase-height calibration, so we designed a circular array of target by the four large circle and 51 small circles composed. Proposed the ellipse recognition algorithms that effectively remove background noise and extract the target region, and verified camera calibration by experiments. In the end, the camera calibration and phase- height calibration can be linked up with a group of photos.Research on the projector phase- height calibration algorithms and phase correction algorithm. Combination camera parameters, using the bilinear interpolation algorithm to extract the landmark phase value, and used for projector phase- height calibration experiment, which laid a foundation for solving three dimensional point cloud. Based on the three step phase shift method and the dual-frequency heterodyne principle, the projector phase calculation algorithm was designed. And analyzed the projection phase error, presented a global phase correction algorithm that dramatically improved the precision of the phase of the projector which had a short projection distance and wide-angle.Research on the theory of solving monolithic point cloud and the method of the key points of the object in the scale space that including the feature information about the object itself was studied. Based on the camera and projector calibration results, calculated the 3d point cloud. The key point of the scale space is applied to the single 3D point cloud mosaic, and the artificial marking points are omitted. The effect of different solution for point cloud mosaic is compared. And final results showed the feasibility of scale-space key point for point cloud stitching.The hardware experiment platform based on the principle of system calibration and the principle of point cloud solution and stitching is studied. Studied With the minimum system of 89C52 microcontroller as the lower computer, the coordination between CCD camera and DLP projector is controlled by the communication between the upper computer and the host computer. The software of PC based on VC++6.0 software development platform was designed for man-machine interaction and setting some important parameters. Design of the system calibration toolbox, not only for rapid system calibration and solving three-dimensional point cloud, but also has some simple image processing functions.