一种高质量的数字高程模型（DEM）建立方法 ——ANUDEM法

建立高质量的数字高程模型（DEM）是正确计算坡度、坡向、提取流域地形特征、进行水文分析的前提，因而在研究土壤侵蚀、植被建设和土地利用规划与评价中都具有重要意义。ANUDEM采用迭代有限微分内插技术和地形强化算法，自动去除伪下陷点和生成输入数据错误文件，便于查错改善DEM质量，并减少了去除伪下陷点的编辑或DEM的后处理过程。本文以黄土高原丘陵沟壑区典型小流域为例，利用大比例尺（1:10000）数字化地形图，利用ANUDEM建立DEM，从DEM光照模拟图、回放等高线、提取水系、坡度等方面对建立的DEM的质量进行了评价。研究表明，ANUDEM建立的DEM表面光滑；回放等高线与原等高线符合度高，能更准确地表现地形起伏；由其提取的坡度准确；水系连续完整与地形图上河流一致，适宜水文分析，是一种建立高质量DEM的优良方法。

A Method to Build High Quality DEMs-ANUDEM Method

The regular grid digital elevation models (DEMs) with high quality are the premise of calculating slope gradient, aspect, and modeling hydrology accurately. With the input data commonly available and the known characteristics of elevation surfaces, ANUDEM utilizes an iterative finite differential interpolation technique and the drainage enforcement algorithm to remove all sink points in the output DEM that have not been identified as sinks in the input sink coverage and ensure connected drainage structure and sensible representation of ridges and streams. In addition, the output diagnostic files are useful to identify large elevation errors and locations where elevation data and streamline data and then improve the quality of the output DEM. Example of a typical catchments in the Loess Hilly and Gully area, the quality of the DEM, which was produced based on the digital map (1:10000) by ANUDEM, was evaluated in terms of the shade map of the DEM, the derived contours map, streamlines and slope form the DEM. The study shows that the surface of DEM is smooth, the contours and the streamlines form the DEM are matching well to the originals and the slope is correct, so such high quality DEM can represent the shape and drainage structure of the real landform accurately. Therefore, ANUDEM is a good method to produce DEMs with high quality.