Research On 3D Surface Splicing Method Based On Three Control Points

Due to large object and revolved body surfaces are often beyond camera view scope, the measurement precision requirements, or partial view is blocked by other parts, the measurement process of these surfaces are often separated into several pieces or times. The joint of separated surface data is necessary in order to make surfaces spliced. Therefore three dimensional surface splicing is one of the core technologies of three-dimensional measurement, and it's also one of the important research fields of computer vision and graphics image processing. It is widely used in reverse engineering, virtual reality, cultural relic protection and medical imaging.A structured light 3D detecting approach based on symbolic M-arrays, which aimed at dynamic 3D scene reconstruction using binary coded light pattern, was proposed by our group. The method is suitable for large targets with large curvature radius. Because there have no remarkable characteristics on the surfaces, therefore they can hardly be spliced by free splicing approaches. Based on three control points on the target surface, an alternated splicing method was proposed in this paper. Simulation experiments were carried out, and the result shown that the proposed splicing method had a certain splicing precision both with robust. The main context of this paper can be summarized as follows:(1) The control points recognition and location .Pre-set control points on the surface of the object, using image smoothing and image segmentation to preprocess the image of the control points. Recognize the control points by using edge detection and edge tracking algorithm, then locate the center of control points by Ellipse Fitting Method and calculate the 3D world coordinates of the control points by analyzing the coordinate of the key points. At the same time, 3D surface was generated by Matlab in experiments.(2) Surface splicing method based on three control points. this paper divides the process of finding a solution to transformation matrix by Surface splicing method based on three control points, using matrix transform to unify the different world coordinate systems to the same coordinate system; Also introduces some commonly used methods of splicing control points, such as using transitional coordinate system to get transformed matrix; Propose the standard how to judge the image after surfaces splicing and provide methods of surface smooth processing .(3) Optimized selection of control points in multipoint control system. This paper analyze the impact on the accuracy by using different control points chosen methods during splicing two surface with many control points, list out the advantages and disadvantages about ICP, proposed a method choosing the best three of all the points as the splicing control points. This paper also defined the principle of optimizing selection about the control points, and verified the reliability of the principle by a series of experiments.