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Mathematical Problems in Engineering
Volume 2016, Article ID 3089690, 14 pages
http://dx.doi.org/10.1155/2016/3089690
Research Article

Identification of Contour Lines from Average-Quality Scanned Topographic Maps

1School of Earth Sciences and Resources, China University of Geosciences (Beijing), Beijing 100083, China
2Beijing Key Laboratory of Development and Research for Land Resources Information, Beijing 100083, China

Received 1 September 2015; Revised 11 December 2015; Accepted 24 December 2015

Academic Editor: Andrzej Swierniak

Copyright © 2016 Bin Xu et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

Contour line is the main linear feature on topographic maps. Extraction of contour lines is tedious and time-consuming process, but is still an interesting problem. This paper presents a novel method for extracting contour lines from average-quality scanned topographic maps. First, it uses spatial fuzzy -means algorithm (sFCM) to solve color aliasing and false color problems by taking into consideration both color and spatial information of topographic maps during color segmentation. In order to improve the categorizing rate, upper and lower cut-sets are introduced into sFCM. Second, to deal with the problem of thick lines, node segments are removed before gaps are repaired. Third, different methods are used to repair contour lines gaps according to the causes, which improves the break points matching accuracy. The performance of the method is tested on several topographic maps comparing with other methods, and the results show that the method can avoid misleading results caused by distortion and wrong branches at intersecting regions when using thinning algorithms and have more accurate and higher quality extraction results.