Acta Geodaetica et Cartographica Sinica ›› 2017, Vol. 46 ›› Issue (2): 218-227.doi: 10.11947/j.AGCS.2017.20160303

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A Line Extraction Method for Chain Code Tracking with Phase Verification

DAI Jiguang1,2, ZHANG Li2, LI Jinwei1, FANG Xinxin1   

  1. 1. School of Geomatics, Liaoning Technical University, Fuxin 123000, China;
    2. Chinese Academy of Surveying and Mapping, Beijing 100039, China
  • Received:2016-06-20 Revised:2016-12-02 Online:2017-02-20 Published:2017-03-07
  • Contact: 张力 E-mail:zhangl@casm.ac.cn
  • Supported by:
    The National Natural Science Foundation of China (Nos. 41271374,61540056,41401535),Key Laboratory of Mapping from Space, National Administration of Surveying, Mapping and Geoinformation (No. K201402),State Key Laboratory of Resources and Environmental Information System

Abstract: A line extraction method for chain code tracking with phase verification was proposed in this study. Firstly, a complete refinement algorithm targeting the Canny edge map was presented. Secondly, an improved chain code tracking method was proposed, and the key algorithm steps were described as follows:detecting the start points of chain code; setting up dynamic main directions to determine the tracking directions of chain code; tracking edge points inside the eight neighborhoods was preferred, and then edge points outside the eight neighborhoods if no edge points existed inside the eight neighborhoods, meanwhile linear analysis was employed to perform dynamic constraints on the chain code. Finally, linear fitting and phase marshalling validation were processed upon the chain code tracking, where straight lines were output when condition were satisfied, otherwise the start points of chain code should be reset to extract straight lines. The experimental results from a variety of different optical image data showed that the proposed algorithm could not only achieve precise fit straight edge information, but also solve the linear fracture problems induced by white noise and phase grouping.

Key words: line extraction, thinning method, chain code tracking, phase verification

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