Processing system of degital elevation data for geomorphological research

为了使地理勘测院编制的"数字国土信息"中的数字高程模型在地貌研究中发挥作用，讨论了以下步骤和算法。利用微机和外围设备建立了DEM数据处理系统，对全国DEM数据进行采集、编辑，对缺失数据的格网和无高程数据的内陆水面进行高程估算。4)网格孔径变化; 5）局部地貌特征计算; 6）小四边形统计参数计算; 7）baove第5项和第6项参数的面统计计算。8)DEM等值线绘制; 9）水系组成及流域面积计算。10)DEM的显示和输出，以下程序也作为附加功能处理：A）转换成带阴影的栅格地图，B）栅格等值线绘制，C）不规则间隔数据的等值线绘制，D）DEM的Affin变换叠加到卫星影像上，E）立体像对变换，F）卫星影像显示。但BASIC也用于图形学中的便利性。

In order for Digital Eleveation Model in "Digital National Land Information" prepared by Geographical Survey Institute, to be useful in geomorphological study, following procedures and algorithms were discussed. And a processing system of DEM was built using a personal computer and peripherals.1) data acquisition from the national DEM, 2) editing for DEM, 3) elevation estimation for data failure grids and inland water surace without elevation data. 4) change of grid aperture, 5) calculation of local geomorphological characteristics, 6) calculation of statistic parameters in small quadrangle, 7) calculation of areal statistics of parameters of baove items 5 and 6. 8) contouring of DEM, 9) composition of drainage system and calculation of drainage area. 10) display and output of DEM.Following procedures ate also treated as additional functions.A) transformation to shaded raster map, B) raster contouring, C) contouring of irregularly spaced data, D) Affin transformation of DEM for overlay to satellite image, E) transformation of stereo pair, F) display of satelite image.The programs of the system are coded mainly in C by reason of rapid I/O of the large files of DEM, but BASIC is also used for coveniences in graphics.