【作者】 王叶飞；

【导师】 刘学军；

【作者基本信息】 长沙理工大学 ， 道路与铁道工程， 2005， 硕士

【摘要】 数字地形分析(Digital Terrain Analysis,DTA)是在DEM上计算地形属性、提取地形特征的地形信息处理技术,其结果是地学建模的基本参数。地形属性的计算精度直接影响地学及其相关学科模型的精度和实际应用的准确性。基于DEM的地形信息提取受到DEM数据结构、DEM分辨率、格网方向、数据误差等结构特征、算法、分析方法等多种因素的影响。深入分析各种地形属性计算的误差问题,提高数字地形分析的精度,为基于GIS(Geographical Information System,GIS)的地学建模和应用提供高质量、高精度的基础数据,是一项十分迫切的任务。 地形曲率(Terrain Curvatures)是表达地形曲面结构的主要参数之一,也是地表过程模拟、土壤侵蚀模型、土地利用分类等环境模型的基本变量。目前国外对曲率的研究虽然很多,但和坡度坡向相比,仍存在很大不足,本文在分析前人研究的基础上,采用“数据独立的误差分析方法”,对规则格网DEM上九种曲率(平面曲率、剖面曲率、切曲率等)的计算精度问题进行了分析研究。本研究主要包括三方面内容: 1)基于DEM的曲率计算模型分析与评价。主要对目前常用的三种曲率计算模型(Evans模型、Shary模型、Zevenbergen模型)的计算精度进行对比评价,实验在模拟DEM上分不同的误差环境进行,并对实验结果在实际DEM上给予验证。 2)曲率计算模型与DEM结构的关系。侧重研究格网DEM本身的结构特征(格网分辨率、格网方向、数据误差)对曲率计算的影响。研究中模拟DEM有无数据误差两种情况进行。 3)曲率误差的空间分布研究。探讨曲率计算的误差的空间分布特征。 通过本文的研究得出以下结论: ①高次曲面虽然能够较为准确的刻画复杂的局部地形曲面特征,但对DEM误差比较敏感,并不适合作为DEM地形参数提取的曲面模型;而低阶曲面对DEM数据误差有一定的平滑作用,比较适合地形参数的提取和分析; ②在各种曲率模型中,当DEM数据精度十分高时,可采用基于四次曲面的Zevenbergen模型进行曲率计算,而当DEM误差较大时,以基于二次曲面的Evans模型为佳。考虑到目前各种精度级别的DEM误差,一般都在分米级到数米之间,因此在实用中推荐使用E模型来计算各种地形曲率; ③平面曲率和流水路径曲率对DEM误差比较敏感,不但与局部曲面模型有更多还原

【Abstract】 Digital Terrain Analysis (DTA) is a topographical information analysis technology that calculates and extracts terrain surface parameters and morphological features on Digital Elevation Model (DEM). Many factors, such as, DEM data structure、 DEM grid resolution、 DEM grid direction、 data accuracy、 algorithm、 analysis methods, etc. can affect the accuracy of the extracting and calculating of terrain surface parameters and morphological features on DEM. The accuracy of DTA affects the applications of GIS models. So, it’s a necessary and urgent task to go deep to study the problems of DTA accuracy if the results of DTA are to be applied in the real world cases.Terrain curvatures is one of the primary terrain surface parameters, and they are primary variables in the earth’s surface process modeling、 soil erode modeling、 classifying of soil utilizing. Though there are many people study terrain curvatures, there’s a great shortage in this field comparing with slop and aspect. In this article, we summarize the former studies in terrain curvature and find the shortage of this field. Here we use the method of data-independent assessment of errors (put forward by xuejun liu, 2002) to study the accuracy of terrain curvatures calculation on DEM. We select nine terrain curvatures studied in this article. And the study include three main contents.1) Accuracy of Algorithms for calculation of terrain curvature based on grid DEM. In this section, we appraise three in common use algorithms for calculation of terrain curvature (shary model、 evans model、 zevenbergen model) in artificial surface and test the conclusion in real surface.. The experiments are carried out in different error condition.2) The relation of terrain curvatures calculation and DEM structures. In this section, we study how the DEM structures (DEM grid resolution、 DEM grid direction、 data accuracy) affect the curvatures calculation.3) The study of spatial distributing of curvatures error. In this section, we study how the error of curvatures calculation distributes in space.In this study, we have conclusion as follows:1) The higher-order local surface (partial quartic surface- Zevenbergen model) can describe the terrain surface accurately. But it is sensitive to data errors. So it is not fit for calculating terrain parameters, lower-order local surface (quadraticsurface-Shary model or Evans model) which is not so sensitive to error can derive more accurate results.2) Zevenbergen model is best if the DEM data is very accurate, otherwise, Evans model is better. There are data errors in DEM presently, so we recommend Evans model to calculate terrain curvatures in actual applications.3) Contour Curvature and flowpath Curvature are sensitive to DEM data errors, they are affected by not only local surface but also slop. Calculating slop accurately is the precondition of enhance the accuracy of this two curvatures calculation. We recommend Evans model to calculate fx and fy in curvature definition.4) Only in the condition that the DEM data is very accurate, accurate resolution DEM can calculate curvatures more accurately. But there are unavoidable and considerable data errors in real DEM, so, the accuracy of curvature enhance by the decrease of DEM resolution.5) DEM direction have a little affect to contour curvature and flowpath curvature. But it count for little. Due to the effect of data error in real DEM, the effect of DEM direction to other seven curvatures is very little.6) There are a reverse relation between true curvature and true error. If the true curvature has a big value in some place, the true error is small in the same place. The inverse is correct too.更多还原