Chinese Journal of Tissue Engineering Research ›› 2012, Vol. 16 ›› Issue (17): 3156-3159.doi: 10.3969/j.issn.1673-8225.2012.17.027

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Automatic removal for pseudo markers in optical positioning system 

Liu Su-juan, Yang Rong-qian, Wu Xiao-ming   

  1. Department of Biomedical Engineering, South China University of Technology, Guangzhou  510006, Guangdong Province, China
  • Received:2011-10-20 Revised:2011-11-30 Online:2012-04-22 Published:2012-04-22
  • Contact: Corresponding author: Yang Rong-qian, Doctor, Lecturer, Department of Biomedical Engineering, South China University of Technology, Guangzhou 510006, Guangdong Province, China bmeyrq@gmail.com Corresponding author: Wu Xiao-ming, Professor, Doctoral supervisor, Department of Biomedical Engineering, South China University of Technology, Guangzhou 510006, Guangdong Province, China bmxmwus@scut.edu.cn
  • About author:Liu Su-juan★, Studying for master’s degree, Department of Biomedical Engineering, South China University of Technology, Guangzhou 510006, Guangdong Province, China scut_bme2011@163.com
  • Supported by:

    Central University Special Funds for Basic Research Operating Expenses of South China University of Technology, No. 2009ZM0235*

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Abstract:

BACKGROUND: The spatial markers can be captured by optical positioning system to form images, in which the feature points are similar and the texture information is difficult to be obtained. There is an ambiguity in stereo matching, which produce pseudo markers. OBJECTIVE: To analyze the process of stereo matching and propose an effective and automatic method for removing the pseudo markers.
METHODS: Because all rays emitted from the same marker lie in the same epipolar plane, the searching for matching feature points could be determined in specific region to reduce the searching area. Pseudo markers existing in stereo matching were removed according to the abrupt change of spatial coordinates of pseudo markers. So the correct markers were obtained.
RESULTS AND CONCLUSION: A simulation operation tool with three markers was tracked in the experiments. 40 groups of images were obtained and δ=0.002 5 was as the initial matching threshold for testing the algorithm. The reconstruction of the movement showed that this method could effectively isolate the pseudo markers. Compared with the real distances, the error of the computed distances of real markers at the same time was 0.284 4 mm, the relative error was 0.48%, which demonstrated the effectiveness and feasibility of the proposed algorithm.

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