基于信息论的不同比例尺DEM地形信息比较分析

运用信息论与数理统计及对比分析的方法，以1：1万DEM为基准，探讨在黄土丘陵沟壑区1：5万DEM所建立的数字高程模型信息特征和对地形描述的精度特征。样区为陕北绥德县韭园沟流域，基本技术平台为ARC／VIEW地理信息系统软件。研究结果表明，在该地区内，利用1：5万DEM手提取的地面坡度、剖面曲率2种地形因子及其熵值都不同程度地存在着差异，熵值变化率分别为6．275％和0．182％，并且提出了信息损失量的计算公式和因子特征的纠正公式，同时从信息论的角度分析了这种差异的本质特征是微观每个栅格地形因子取值的不确定性变化。

A Comparison of Topographic Information from Different Scales DEM s Based on Information Theory

Applying information theory, mathematical statistics and comparative laws as a basic research methodology and 1:10,000 DEM as a criterion, the information characters and accuracy of topographic variables derived from DEMs of 1:50,000 map scale were made to investigate by means of a careful comparison with 1:10,000 scaled DEMs. Taking Jiuyuan area, in Suide county,Shannxi Province,P.R.China, as a test area and ARC/VIEW as a main working platform, the results of research proved that, in the testing area, different errors can be found in the topographic factor such as slope gradient and profile curvature, loss of uncertainty magnitude:6.275%, 0.182%. And then, the calculating formula of information loss and revising formula of factors characters were proved. At the same time, essential characters of these errors were analyzed based on information theory. It is the uncertain variance of topographic factors derived from every microscopical grid that causes the above mentioned errors.