论DEM地形分析中的尺度问题

DEM及其地形分析具有强烈的尺度依赖特征。本文以黄高原地区的研究为例,结合地学建模和地学模拟的需求,重点讨论DEM地形分析中的尺度问题。文中从DEM建立与应用出发,首先建立了DEM地形分析中的尺度概念体系,剖析了各类尺度之间的关系,其次讨论了尺度所引起的各种地形分析效应问题,最后探讨了DEM地形分析中的尺度转换类型和方法。

Scale issues in digital terrain analysis and terrain modeling

Digital elevation model(DEM) and terrain analysis based on DEM is scale-dependant.With the view of geoscience analysis and modeling,the paper mainly discusses scale and scale effect of terrain analysis based on grid DEM.! Firstly,the paper outlines five common uses of the term "scale" within DEM and terrain analysis which are geographical scale,sampling scale,DEM structure scale,analysis scale and cartographic scale.The geographical scale means the spatial extent of the DEM or the area of coverage;the sampling scale refers to sampling intervals in DEM data collection;the DEM structure scale refers to the resolution of DEM which includes DEM horizontal resolution and vertical resolution;the analysis scale refers to the analysis extent of local windows including window size and threshold value;and the cartographic scale which is used for map reflects the ration between the measurements on a map and the actual measurement on the ground. Secondly,the paper's focus is put on the scale effect of terrain analysis based on DEM.In this section,the uncertainty of DEM and terrain analysis caused by the above scales is classified into single scale effect,cross scale effect and boundary effect.One area of terrain analysis that has been largely ignored is the effect of variability of terrain within the bounds of single grid cell that is referred to the heterogeneity effect of DEM grid size in the paper.We pointed out those and discussed the effect on terrain analysis.At the end of this section,the scale threshold which can be used to indicate the effective extend of terrain attributes is discussed. It is known that the existing DEM with fixed resolution does not always meet the requirement of application.This means that one can deduct more scale terrain models from a fixed resolution DEM.In fact,scaling model can realize the terrain information allocation and aggregation in terrain analysis based on DEM.In this paper,three scaling models including scale deduce model,scale inversion model and multi-scale terrain analysis model are discussed.