从规则高程格网中提取等高线的优化算法研究

从规则高程格网中提取等高线的算法是机助制图和GIS中非常重要的组成部分。本文针对当前高程格网数据的海量性,以提高效率为目的,对该算法进行了优化。将等高线提取算法分为起点确定和内插穿行两个阶段,对于第一个阶段的处理,提出基于区间树和顺序索引查找等高线起始点的算法,较大地改善了整体效率;同时,在顾及数字环境下等高线表达特性的基础上,设计的相关策略能够保证提取的等高线具有一致的方向信息。

The Improved Algorithm for the Extraction of Contour Lines from Grid DEM

The extraction of contour lines from Grid DEM is a primary function in computer-aided cartography and GIS. The Grid DEM is being the main data source of elevation data due to the fast development of data acquiring technology. This paper designs a new efficient algorithm to extract contour lines based on index. The algorithm partitions this procedure into two phases: determination of heading point and threading. We design three structures which include interval tree, ordinary sorting and bucket sorting to facilitate the procedure to determine of heading points, which has not been recognized carefully in existing research. The result is very encouraging on efficiency issue. Another new result is that the contour lines extracted by our algorithm are in the same direction which provides more information for further terrain analysis based on contour.