共查询到18条相似文献，搜索用时 140 毫秒
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局部曲面正切曲率与流线曲率的水流路径算法 总被引：1，自引：0，他引：1
在局部特殊地形如细窄的沟渠等地带,水流方向可能是惟一的,即当前点的水应全部流入下游惟一的格网点,此时若采用多流向算法不仅会导致水流方向产生较大误差,而且可能影响区域汇水面积的精确计算。为解决此问题,本文提出了一种水流路径算法,该算法通过以各格网点为中心建立3×3窗口范围内的局部趋势面,利用该点在局部趋势面中的正切曲率和流线曲率选取合适的单流向或多流向算法来确定并计算该点的水流流向及流量分配比例。最后通过实例证明了该方法在水流累积量计算中的良好效果,并在一定程度上为格网DEM沟谷段和分水线段的提取奠定了基础。 相似文献
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在局部特殊地形如细窄的沟渠等地带,水流方向可能是惟一的,即当前点的水应全部流入下游惟一的格网点,此时若采用多流向算法不仅会导致水流方向产生较大误差,而且可能影响区域汇水面积的精确计算。为解决此问题,本文提出了一种水流路径算法,该算法通过以各格网点为中心建立3×3窗口范围内的局部趋势面,利用该点在局部趋势面中的正切曲率和流线曲率选取合适的单流向或多流向算法来确定并计算该点的水流流向及流量分配比例。最后通过实例证明了该方法在水流累积量计算中的良好效果,并在一定程度上为格网DEM沟谷段和分水线段的提取奠定了基础。 相似文献
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流域栅格河网提取是数字地形分析的一个重要应用。为减少数字高程模型(DEM)预处理而产生的伪河道及平行河道,提出基于并行化多流向策略的栅格河网提取算法。通过水流传输矩阵模拟水量的自然流动过程,可直接应用于原始DEM。从河网空间形态和算法运行效率两方面与串行MFD算法、R&N算法及D8算法进行对比,结果表明,多流向策略得到的河网与实际地形形态更加吻合,使用并行策略后,算法的效率比也较其他算法有明显提升。 相似文献
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提出一种基于汇水区合并的结构化DEM综合方法。使用汇水区作为联系谷地实体与DEM数据网格点的纽带,在次要谷地删除的基础上进行谷地汇水区的合并,以合并后的汇水区边界线(汇水区边界包含山脊线、山顶和鞍部三种地形骨架)和谷底线为约束条件进行DEM内插,从而实现结构化DEM综合。实验表明,该方法在删除次要地形特征的同时,能较好地保持主要地形结构特征。 相似文献
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小比例尺DEM制作的晕渲图地形破碎,含有大量的干扰细节,不利于从宏观上把握地形的骨架。为了增强数字地貌晕渲图中的地形特征,本文利用滤波和平面曲率相组合的DEM化简方法来描述山谷和山脊区域。分别针对盆地、平原和山地三种地貌类型,采用90 m、100 m和110 m三种分辨率的DEM数据进行实验,研究发现,这三种地貌类型最佳的山脊夸张系数都为1.3,相应的山谷深化系数分别为0.4、0.6和0.8;而三种分辨率情况下山地的最佳山谷深化系数都为0.8,且山脊的夸张系数都为1.3。 相似文献
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胡应剑 《测绘与空间地理信息》2018,(1):167-171
随着GIS技术的不断发展和DEM的广泛应用,基于DEM的流域水文特征分析研究受到越来越多的关注。目前,基于格网DEM的水流方向算法,会因为地形的局限,无法准确地进行模拟分流,水流方向也不符合实际流向。本文分析了几种基于DEM的水流方向算法,以格网点为中心建立3×3窗口的局部趋势面,计算出研究区内的曲率,分析区域内的水流聚合度和发散性随着曲率的变化情况,最后根据水流方向算法提取河网。 相似文献
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DEM数据辅助的山脊线和山谷线提取方法的研究 总被引：13，自引：2，他引：13
从数字化地形资料中自动提取山脊线和山谷线的技术在测绘、工程设计等方面有着重要的意义。本文对现有的山脊线和山谷线自动提取的方法进行深入研究后 ,指出充分利用数据中所含有的地形信息是正确提取山脊线和山谷线的有效途径 ,那种试图仅依靠二维等高线形态分析的方法很难得到理想的结果。依照该思想本文设计出了一种基于DEM数据辅助的山脊线和山谷线提取方法。该方法先利用等高线数据建立区域地形概略DEM ,然后借助三维地形分析的技术辅助进行山脊线和山谷线的提取。文后通过实验验证了该方法的有效性 ,它所提取的山脊线和山谷线与实际地形相符合。 相似文献
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Igor V. Florinsky 《Transactions in GIS》2017,21(6):1115-1129
Digital elevation models (DEMs) are commonly constructed using two main types of regular grids: plane square grids and spheroidal equal angular grids. Methods and algorithms intended for plane square‐gridded DEMs should not be directly applied to spheroidal equal angular DEMs. This is because these grids have fundamentally different geometry. However, some researchers continue to apply square‐grid algorithms to spheroidal equal angular DEMs. It seems appropriate to consider once again the specifity of morphometric treatment of spheroidal equal angular DEMs. This article, first, demonstrates possibilities of direct calculation of local, nonlocal, and combined morphometric variables from spheroidal equal angular DEMs exemplified by slope gradient, catchment area, and topographic index. Second, the article shows computational errors when algorithms for plane square‐gridded DEMs are unreasonably applied to spheroidal equal angular DEMs. The study is exemplified by two DEMs. A medium‐resolution DEM of a relatively small, high‐mountainous area (Mount Elbrus) was extracted from the SRTM1 DEM. A low‐resolution DEM of a vast region with the diverse topography (the central and western regions of Kenya) was extracted from the SRTM30_PLUS DEM. The results show that application of square‐grid methods to spheroidal equal angular DEMs leads to substantial computational errors in models of morphometric variables. 相似文献
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《制图学和地理信息科学》2013,40(3):215-230
This research investigated the dependence of computing downslope flow from digital elevation models (DEMs) on two basic elements of the flow calculation: the spatial resolution of the DEM and the algorithm used to compute the downslope flow, specifically how it defines topographic slope and aspect. Six algorithms for downslope flow and downslope accumulation were implemented in MATLAB using different assumptions about components of the computation from the terrain analysis literature. We analyzed the results of downslope flow statistically, thresholded the values to yield streams, and compared the different results with the actual surface streams in the National Hydrographic Database. We repeated the computations using DEMs of 3-m, 30-m, and 90-m resolutions, covering a test area near Santa Barbara, California. We conclude that downslope flow computations are overestimates, and that they are fraught with critical algorithmic assumptions and scale effects. They should be approached with great caution in GIS-based analyses. 相似文献
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A Comparison Between Contour Elevation Data Sources for DEM Creation and Soil Carbon Prediction, Coshocton, Ohio 总被引：1，自引：0，他引：1
A raster and vector GIS was created for the North Appalachian Experimental Watershed (NAEW) from legacy (1960) 1:2,400‐scale contour maps. The intent of the study was to use terrain data for the spatial modeling of soil organic carbon. It was hypothesized that DEMs derived from these data would be more accurate and therefore more useful for terrain‐based soil modeling than those from USGS 1:24,000‐scale contour data. Central tasks for this study were to digitally capture the 1:2,400‐scale maps, convert digital contour data sources to raster DEMs at multiple resolutions, and derive terrain attributes. A flexible approach was adopted, using software outside of mainstream GIS sources where scientifically or practically advantageous. Elevation contours and streamlines were converted to raster DEMs using ANUDEM. DEMs ranging in resolution from 0.5–30 m were tested for accuracy against precision carrier‐phase GPS data. The residual standard deviation was 1.68 meters for the USGS DEM and 0.36 meters for the NAEW DEM. The optimal horizontal resolution for the NAEW DEM was 5 m and for the USGS 10 m. Five and 10 m resolution DEMs from both data sources were tested for carbon prediction. Multiple terrain parameters were derived as proxies for surficial processes. Soil samples (n = 184) were collected on four zero‐order watersheds (conventional tillage, no‐till, hay and pasture). Multiple least squares regressions (m.l.s.) were used to predict mass C (kg m?2, 30 cm depth) from topographic information. Model residuals were not spatially autocorrelated. Statistically significant topographic parameters were attained most consistently from the 5 m NAEW DEM. However, topography was not a strong predictor of carbon for these watersheds, with r2 ranging from 0.23 to 0.58. 相似文献
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Traditionally, stream and sub‐watershed characterization in GIS has been accom‐ plished using a DEM‐based terrain analysis approach; however, there is a large amount of existing vector hydrographic data difficult to accurately reproduce using DEMs. WaterNet is a GIS/hydrologic application for the integration and analysis of stream and sub‐watershed networks in vector format. Even with vector data, hydrologic inconsistencies between streams and sub‐watersheds do exist, and are revealed in the form of streams crossing drainage divides and sub‐watersheds with more than one outlet. WaterNet rectifies these inconsistencies and couples the two datasets. Most algorithms involving traces of dendritic networks employ a form of tree traversal which requires topologic information to be organized into specialized data structures. On the contrary, WaterNet develops topologic relationships from GIS attribute tables, which, in combination with sorting and querying algorithms, make the calculation process efficient and easy to implement. With the topologic relationships of the streams and sub‐watersheds, WaterNet can perform traces to calculate cumulative network parameters, such as flow lengths and drainage areas. WaterNet was applied to the catchment of the Texas Gulf coast for a total of 100 cataloging units (411,603 km2) and 60,145 stream lines (183,228 km). 相似文献
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Effect of Contour Intervals and Grid Cell Size on the Accuracy of DEMs and Slope Derivatives 总被引：5，自引：0，他引：5
Feras M Ziadat 《Transactions in GIS》2007,11(1):67-81
Digital Elevation Models (DEMs) are indispensable tools in many environmental and natural resource applications. DEMs are frequently derived from contour lines. The accuracy of such DEMs depends on different factors. This research investigates the effect of sampling density used to derive contours, vertical interval between contours (spacing), grid cell size of the DEM (resolution), terrain complexity, and spatial filtering on the accuracy of the DEM and the slope derivative. The study indicated different alternatives to achieve an acceptable accuracy depending on the contour interval, the DEM resolution and the complexity of the terrain. The effect of these factors on the accuracy of the DEM and the slope derivative was quantified using models that determine the level of accuracy (RMSE). The implementation of the models will guide users to select the best combination to improve the results in areas with similar topography. For areas with variable terrain complexity, the suggestion is to generate DEMs and slope at a suitable resolution for each terrain separately and then to merge the results to produce one final layer for the whole area. This will provide accurate estimates of elevation and slope, and subsequently improve the analyses that rely on these digital derivatives. 相似文献