黄土丘陵沟壑第三副区水文地貌关系正确DEM的建立与评价

本文以黄土丘陵沟壑第三副区的藉河流域为研究区,利用ANUDEM软件和1:5万地形图研究了水文地貌关系正确DEM的建立方法,从派生等高线与原始数字化等高线对比等方面对建立的DEM进行了质量评价。并且与传统TIN方法建立的不同水平分辨率的DEM做了比较。结果表明:由等高线、高程点、河流和陡崖线在ANUDEM5.1中生成的DEM质量优于由等高线、高程点和地形特征点用TIN方法生成的DEM。ANUDEM建立的DEM更能精确地反映水文地貌特征。在此基础上,研究了确定集水面积阈值的方法,通过在Arc/Info环境下运行AML程序自动提取了基于水文地貌关系正确DEM的流域特征。     

用ANUDEM建立水文地貌关系正确DEM的方法研究

针对区域尺度的径流、水土流失定量评价和植被适宜性评价等研究工作需要,利用1∶25万数字地形图和ANUDEM软件,对黄土丘陵区中等分辨率水文地貌关系正确DEM建立方法进行了研究。结果表明该方法所建立的DEM,可以正确反映地貌梁、沟结构及其与流水线网络的关系,对地形描述的能力优于TIN方法建立的DEM;利用ANUDEM和1∶25万地形图插值建立黄土丘陵区DEM的三个主要参数分别为分辨率50或100,计算迭代次数40,第二糙率系数0.8。     

Improving a digital elevation model by reducing source data errors and optimising interpolation algorithm parameters: An example in the Loess Plateau,China

A hydrologically correct digital elevation model (DEM) forms a basis for realistic environmental modelling, especially in complex terrain. We have performed a study in the Coarse Sandy Hilly Catchments (CSHC) of the Loess Plateau, China, which demonstrates pragmatic, yet effective methods for improving the quality of the DEM by: (1) identifying and correcting source topographic data errors and (2) optimising ANUDEM algorithm parameters. Improvement in the DEM based on fixing over 1100 errors in the input topographic data, and optimising key ANUDEM parameters was assessed using higher accuracy independent validation of 32 contributing areas and 1474 spot heights, and by semi-quantitative analysis of DEM derivatives produced from ANUDEM and Triangular Irregular Network (TIN) algorithms. Improvement in the ANUDEM DEM over the original TIN DEM was shown where the percentage of the total absolute difference in contributing areas reduced from 10.43 to 3.51%, and the bias between the spot heights and DEM elevations reduced from 45 to 32 m. Large improvement in DEM quality was gained by using ANUDEM instead of TIN, with smaller improvement gained by fixing source data errors, and optimising ANUDEM parameters.     

基于Hutchinson的DEM建立及质量评价

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。国外应用最广的是基于Hutchinson方法的DEM插值方法和应用该算法的软件ANUDEM,该软件采用有限微分内插技术和地形强化算法,自动去除伪下陷带点和生成输入数据错误文件。研究表明,通过等高线回放、DEM中误差、坡度、河流、光照模拟等方面的对比,ANUDEM生成的DEM表面光滑,比常规用TIN方法构建的TIN-DEM更能准确地表现地形起伏,其提取的坡度、光照图更准确,适宜进行水文分析。     

散乱数据内插平原地区DEM的方法

以我国东部平原地区钱营孜煤矿矿区为案例,根据实测的散乱数据,使用交叉统计检验和视觉特征分析了ANUDEM方法和与地理信息系统领域中常用传统插值方法的空间插值结果。分析表明,在平原地区,TIN方法生成的DEM具有较高的精度,ANUDEM方法生成的DEM能够准确反映水文地貌。     

基于ANUDEM与山脊抬升的DEM简化

为在DEM简化过程中充分保留地形骨架信息,提出一种基于ANUDEM与山脊抬升的DEM简化方法。利用ANUDEM插值法获得顾及水文要素的DEM简化表面,并对简化DEM实施山脊抬升,从而得到顾及地形骨架的简化表面。实验表明,在简化DEM中实施山脊抬升能够更大程度地增强简化表面山体结构的保留程度,且随着地形简化程度的降低,山脊抬升法的作用也逐渐增大。     

An improved ANUDEM method combining topographic correction and DEM interpolation

Void filling and anomaly replacement in conjunction with auxiliary sources of data have been widely used to improve the quality of existing problematic high-resolution digital elevation models. However, the traditional interpolation methods used for this purpose have always failed to eliminate the discrepancies between different data-sets. In this paper, an improved ANUDEM method is presented for DEM interpolation, which incorporates the idea of topographic correction using high correlation of topological structure between contour lines (CLs) from multi-scale digital elevation models (DEM). Firstly, the terrain topological structure is extracted from the CLs of a low-resolution DEM. The topographic surface correction is then undertaken based on the extracted structure, which recovers the topographic information of the sharp depressions and eminences to fit the high-resolution representation. Finally, the breaklines of the terrain surface are distilled and integrated into the denser DEM generation. The experiments undertaken confirmed the superiority of the proposed method over the other DEM interpolation methods. It is shown that the proposed method can provide results with a higher accuracy, as well as a better visual quality.     

地形平坦地区DEM生成算法的比较研究

数字高程模型(DEM)是GIS的基础数据之一,是许多涉及高程信息的空间分析的重要基础。DEM插值精度的好坏直接影响基于DEM的各种地学分析及应用,因此研究高精度的DEM插值算法具有重要意义。介绍了基于水文强化算法的DEM插值算法——ANUDEM,并与传统的TIN建立DEM的算法进行了比较。认为在地形复杂地区由于等高线密集,高程信息丰富,两种插值算法效果都比较好;而在地形平坦地区ANUDEM算法精度优于TINDEM,并且,ANUDEM得到的DEM很好地避免了平山顶、阶梯状地形,其派生的等高线和水系与原始数据更加吻合。相对于TINDEM算法,ANUDEM算法更适合地形平坦地区的DEM建立。