基于断点分类和方向差异的等高线分级补断方法

Iteration approach for contour lines reconstruction based on breakpoint classification and orientation difference

扫描地图等高线的自动识别是当前GIS领域的研究热点,但图像分割后提取的等高线上往往存在着各种断点.现有的等高线断点连接方法不能有效连接断裂过大的等高线,并且容易造成近似平行的等高线处断点的错连.针对以上两个问题,本文提出了一种高效的补断策略:首先根据等高线断点的特征将其分成三类,然后再针对每类断点采用不同的匹配方法.其中,对于最常见的中间断点,引入了改进的方向差异计算方法,以解决平行等高线间的错连问题;结合分级补断的思想,能有效地对等高线断裂过大处进行连接.实验结果表明,相比于常规最小点对法,该算法在时间效率和连接准确率方面具有较大的优势.

The automatic recognition of contour lines research topic in GIS. But after image segmentation, from scanned digital topographic maps is a popular there often are various gaps between the extracted contour lines. Most of the past methods for broken point connection cannot process the big gaps and easi- ly cause false connection among the parallel lines. In this paper, an efficient approach to solve this prob- lem is proposed. Firstly these broken points are divided into three types according to their features, and then different connection strategies for each type breakpoint are respectively implemented. For the type of intermediate breakpoint, an improved calculation method of orientation difference is introduced to solve the false connection among the parallel lines. And the connection process is carried out iteratively many times, so that the big gaps of contour lines can be effectively connected. The comparative experi- mental results show that breakpoint connection performance and accuracy have been improved by the proposed approach.