The isoline extracted from DEM is one of the basic functions of computer mapping and geographic information system.This paper proposes an isoline extraction method based on interval tree from DEM. This paper references the algorithm of inserting elements in balance binary sort tree to create interval tree's nodes; when searching the grids the contour line passed, it just sorts those grids which are belonged to the nodes the search path passed, avoids sort all grids in the interval tree, and reduces the search time. Experimental results show that the algorithm has an advantage in time than the older algorithm.%从DEM中提取等值线是计算机制图和地理信息系统的基本功能之一.本文提出一种基于区间树索引的等值线提取算法.借鉴在平衡二叉排序树中插入元素的算法来建立区间树结点;在查找等值线经过的网格时,仅对搜索路径上区间树结点的网格队列排序,避免对区间树全部结点的网格队列排序.实验表明,此算法较以往算法在时间上具有优势.
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