Measurement Techniques Based On The Visual Coordinates Of The Laser Grid Mark

After systematic researches on the newest computer vision coordinate measuring technology and the image acquiring and processing technology, this paper brought forward a vision coordinate measuring technology based on the rectangular grid laser mark, and put it into use in a real vision coordinate measuring system. This technology filled up the blank of related fields in our country. It overcome the shortcomings of being unstable and low efficiency that other measuring means have.This technology works as the following:1. A sheet of rectangular grid laser mark should be cast on the surface of the measured object. The rectangular grid nodes will be treated as measurement marks.2. The images of the rectangular grid mark should be processed into the objective pattern.3.The rectangular grid nodes should be extracted from the images.4. The rectangular grid nodes in each images should be matched one by one.5. Through the three dimensional computation, the coordinates of every grid nodes can be worked out.This vision measuring system employs four CCD cameras as the image acquisition source. This paper designed and realized some of the algorithms mentioned above. The research production can be described as the following:1. The production of the rectangular grid laser mark. In order to produce the proper grid laser marks, the laser mark producer should be designed with proper focal length, the proper intensity and the proper combining means. After the experiments through and through, this paper find a proper laser mark producer at last. And some of the important parameters were described exactly.2. The collocation and the processing of the marking images. In order to extract the rectangular grid mark from the images, this paper presented proper image collecting plans. And in the process of the image collection, there exists some interfere elements, such as the lubricity , the color , the texture and the reflection of the measured object's surface. And there also exists some electronic interfere in the camera itself. This paper uses some proper measures to eliminate the interferes, and an effect image collecting plan was worked out. In order to process the collected digital images into "the patterns that can be distinguished easily and quickly, this paper used some proper image processing measures. The operation of the subtraction of the images was used to extract the rectangular grid marks. And some of interferes produced in the process of image collection was effectively solved. Some of the useful information might be damaged unavoidable, so some so called image serial equilibration and optimal threshold select problems was presented. At the same time some effective plans were brought forward to solve the problems of burr and rupture emerged during the process of the thinning.3. The extraction and the matching of the rectangular grid nodes. The matching measures this paper presented sufficiently took advantages of the initiative markingmeasures. The rectangular grid nodes were not produced by direct means but by the combination of two mark images. In this case, this paper flexibly arranged the order of the image processing and the producing of the grid nodes and in this way the match of the nodes is transferred into the match of the lines, and reduced the complicity of matching problems.Qingbo Yin (Computer software & theory)Directed by Yi Fang...