共查询到19条相似文献，搜索用时 171 毫秒
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栅格DEM的水平分辨率对地形信息的影响分析 总被引：4，自引：0，他引：4
数字高程模型（DEM）是当前用于地形分析的主要数据源,可以从DEM提取不同的地形因子得到地形信息为各种地学分析提供基础服务。对三峡库区应用6种不同网格分辨率进行地形因子数据的提取和分析。研究表明,DEM的水平分辨率对地形信息的精确性有影响,网格的增大增加了DEM对地形信息的概括．应根据不同的需要选择不同分辨率的DEM。 相似文献
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利用分形随机算法建立平地、丘陵和山地3种精细地形仿真场景,将DEM逐级重采样为不同网格间距,分析不同DEM网格间距对3种地形的重力近区地形改正误差影响。发现随着DEM网格间距的增加,近区地形改正误差随之增大。对于平地,使用1∶10 000的DEM,网格间距为5m仍能够满足规范要求;对于丘陵地,使用1∶5 000的DEM,网格间距为2.5m能够满足规范要求;对于山地,使用1∶1 000的DEM,网格间距1m能够满足规范要求。通过消费级无人机获取丘陵地精细地形,验证地形仿真的结论,同时说明消费级无人机能够应用于重力近区地形改正。 相似文献
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在基于LRIS-3D系统建立高分辨率DEM基础上,以黄土高原丘陵沟壑区桥沟小流域为对象,利用GIS工具,以三维激光扫描系统扫描数据为基础数据,研究基于DEM的数字地形特征和水文特征的提取与分析方法。研究结果表明：与普通DEM相比,高分辨率DEM提取研究区平均坡度变小、坡度标准差变大,总体地形向平坦转化,坡面曲率增大,沟壑密度增大,更详细地描述了地表特征。对流域水文过程分析、特别是对流域汇流的参数确定及汇流模型的建立有积极作用。 相似文献
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在OpenGL、Java3D等传统的三维建模语言中有多种三维坐标提取的算法,但应用到三维地形时这些算法的速度太慢,不能满足人机交互的需求。本文研究了点取射线与DEM模型的空间特性,提出并实现了一种基于Java3D的规则网格DEM鼠标提取坐标算法,该算法在利用了规则网格DEM模型特征的基础上,利用点取射线与DEM网格在水平面投影上的相交性进行点取网格搜索,实现了三维坐标的点取。通过实验表明,该算法与三维场景中通常所用的空间点取算法相比,在不降低点取精度的基础上对点取速度有了明显的改进,从而满足了在DEM场景中进行三维交互的需要。 相似文献
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不同空间尺度DEM地形信息容量综合对比研究 总被引：1，自引：0，他引：1
DEM包含了大量地形信息,是进行地形分析的基本数据。由于DEM数据的多尺度因素,加之地形、地貌特征具有宏观性与区域分异性的特点,不同尺度下的DEM地形信息容量具有较大的差异。本研究选取黄土高原地区的绥德、佳县、富县和宜君县四个实验样区,以Arc view/GIS软件为技术平台,提取了基于DEM数据的地形因子,并运用比较分析与数理统计的方法,对地形因子的提取结果进行了分析,获取了单一值因子的量化表达模型,确定了DEM地形信息容量与分辨率、地域及比例尺之间的量化相关关系,并在此基础上分析了DEM地形信息容量在不同空间尺度上的分异规律。 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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基于栅格DEM（digital elevation model）计算局域地形属性时,所采用的分析窗口将直接影响数字地形分析结果,因此在实际应用中应选择适宜分析窗口。由于地形条件是随空间变化的,因此随空间变化的适宜分析窗口应比通常所用的全局固定的3×3窗口更为合理。目前通过定量计算获得随空间变化适宜分析窗口的方法是多窗口局部地表形态刻画法。选用3个具有不同地形特征的研究区,在不同分辨率下分别将坡度、剖面曲率用于该方法来确定适宜分析窗口,对实验结果进行分析评价。结果表明,当利用不同地形信息时,所得的适宜分析窗口情况明显不同。进一步的实验分析发现,与传统所用的全局固定3×3窗口相比,该方法所识别出的随空间变化的适宜分析窗口结果对于实际应用结果没有明显差别。因此该方法有效性存疑,尚不能作为确定适宜分析窗口的有效方法,还需进一步开展方法研究,以设计出合理有效的方法来识别随空间变化的适宜分析窗口。 相似文献
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数字高程模型DEM精度研究 总被引：2，自引：0，他引：2
用不同地貌类型地区的实验数据对数字高程模型(规则格网DEM)的格网间距与中误差(RMSE)、平均高程、剖面曲率的关系进行研究,采用比较分析的方法,得到格网间距与中误差的数学模型,可以用通式:Y=A BX CX2表示,并且把地形因子(平均高程、剖面曲率)作为自变量,进一步分析通式中3个系数与地形因子的关系,发现两个地形因子与系数函数关系比较相似,并得到Y=A BX CX2 DX3的数学模型。由验证结果表明,所得模型效果良好。 相似文献
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The Effect of DEM Raster Resolution on First Order, Second Order and Compound Terrain Derivatives 总被引：8，自引：0，他引：8
Stefan Kienzle 《Transactions in GIS》2004,8(1):83-111
It is well known that the grid cell size of a raster digital elevation model has significant effects on derived terrain variables such as slope, aspect, plan and profile curvature or the wetness index. In this paper the quality of DEMs derived from the interpolation of photogrammetrically derived elevation points in Alberta, Canada, is tested. DEMs with grid cell sizes ranging from 100 to 5 m were interpolated from 100 m regularly spaced elevation points and numerous surface‐specific point elevations using the ANUDEM interpolation method. In order to identify the grid resolution that matches the information content of the source data, three approaches were applied: density analysis of point elevations, an analysis of cumulative frequency distributions using the Kolmogorov‐Smirnov test and the root mean square slope measure. Results reveal that the optimum grid cell size is between 5 and 20 m, depending on terrain com‐plexity and terrain derivative. Terrain variables based on 100 m regularly sampled elevation points are compared to an independent high‐resolution DEM used as a benchmark. Subsequent correlation analysis reveals that only elevation and local slope have a strong positive relationship while all other terrain derivatives are not represented realistically when derived from a coarse DEM. Calculations of root mean square errors and relative root mean square errors further quantify the quality of terrain derivatives. 相似文献
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In this study, landslide susceptibility assessments were achieved using logistic regression, in a 523 km2 area around the Eastern Mediterranean region of Southern Turkey. In reliable landslide susceptibility modeling, among others, an appropriate landslide sampling technique is always essential. In susceptibility assessments, two different random selection methods, ranging 78–83% for the train and 17–22% validation set in landslide affected areas, were applied. For the first, the landslides were selected based on their identity numbers considering the whole polygon while in the second, random grid cells of equal size of the former one was selected in any part of the landslides. Three random selections for the landslide free grid cells of equal proportion were also applied for each of the landslide affected data set. Among the landslide preparatory factors; geology, landform classification, land use, elevation, slope, plan curvature, profile curvature, slope length factor, solar radiation, stream power index, slope second derivate, topographic wetness index, heat load index, mean slope, slope position, roughness, dissection, surface relief ratio, linear aspect, slope/aspect ratio have been considered. The results showed that the susceptibility maps produced using the random selections considering the entire landslide polygons have higher performances by means of success and prediction rates. 相似文献
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Stability investigations of a discrete downward continuation problem for geoid determination in the Canadian Rocky Mountains 总被引：6，自引：0，他引：6
Z. Martinec 《Journal of Geodesy》1996,70(11):805-828
We investigate the stability of a discrete downward continuation problem for geoid determination when the surface gravity observations are harmonically continued from the Earth's surface to the geoid. The discrete form of Poisson's integral is used to set up the system of linear algebraic equations describing the problem. The posedness of the downward continuation problem is then expressed by means of the conditionality of the matrix of a system of linear equations. The eigenvalue analysis of this matrix for a particularly rugged region of the Canadian Rocky Mountains shows that the discrete downward continuation problem is stable once the topographical heights are discretized with a grid step of size 5 arcmin or larger. We derive two simplified criteria for analysing the conditionality of the discrete downward continuation problem. A comparison with the proper eigenvalue analysis shows that these criteria provide a fairly reliable view into the conditionality of the problem.The compensation of topographical masses is a possible way how to stabilize the problem as the spectral contents of the gravity anomalies of compensated topographical masses may significantly differ from those of the original free-air gravity anomalies. Using surface gravity data from the Canadian Rocky Mountains, we investigate the efficiency of highly idealized compensation models, namely the Airy-Heiskanen model, the Pratt-Hayford model, and Helmert's 2nd condensation technique, to dampen high-frequency oscillations of the free-air gravity anomalies. We show that the Airy-Heiskanen model reduces high-frequencies of the data in the most efficient way, whereas Helmert's 2nd condensation technique in the least efficient way. We have found areas where a high-frequency part of the surface gravity data has been completely removed by adopting the Airy-Heiskanen model which is in contrast to the nearly negligible dampening effect of Helmert's 2nd condensation technique. Hence, for computation of the geoid over the Canadian Rocky Mountains, we recommend the use of the Airy-Heiskanen compensation model to reduce the gravitational effect of topographical masses.In addition, we propose to solve the discrete downward continuation problem by means of a simple Jacobi's iterative scheme which finds the solution without determining and storing the matrix of a system of equations. By computing the spectral norm of the matrix of a system of equations for the topographical 5 × 5 heights from a region of the Canadian Rocky Mountains, we rigorously show that Jacobi's iterations converge to the solution; that the problem was well posed then ensures that the solution is not contaminated by large roundoff errors. On the other hand, we demonstrate that for a rugged mountainous region of the Rocky Mountains the discrete downward continuation problem becomes ill-conditioned once the grid step size of both the surface observations and the solution is smaller than 1 arcmin. In this case, Jacobi's iterations converge very slowly which prevents their use for searching the solution due to accumulating roundoff errors. 相似文献
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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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NASA World Wind海量离散地形显示技术研究 总被引：1，自引：0，他引：1
虚拟数字地球需要解决大范围海量地形快速显示问题。本文在对World Wind海量地形显示机理和地形数据LOD分层组织深入研究基础上,提出了基于ArcMap的离散地形分层切割流程,开发了与World Wind三维地形显示数据模型匹配的分层切割软件,对海量离散地形按不同分块大小和层次切割后的显示效率和效果进行了分析,结果表明World Wind能实现不同尺度地形数据的快速三维可视化。 相似文献
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利用流域边界和坡向差自动提取山脊线 总被引：4，自引：0，他引：4
目前山脊线的提取方法以地表曲率分析为主,其成果山脊线连续性差,实用性较难保证。其他基于流水模拟的方法也有提取成果与山脊线定义不相符等缺点。本文介绍了一种整合地表曲率分析和流水模拟2种方法各自优势来提取山脊线的方法。该方法以地表流水模拟提取的流域边界为基础,并以边界两侧地形坡向差值为地表曲率代用指标,对流域边界进行筛选来提取山脊线。本文方法具有成果山脊线连续性好、地形代表性高的特点;并能够正确提取绝大多数的地形山脊线,具有较高的几何精度。 相似文献
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基于自然间断点分级法的土地利用数据网格化分析 总被引：4，自引：0，他引：4
土地利用在自然资源统一管理中扮演着重要角色，面对不同区域和年份的数据，统一分析比对口径尤为重要，同时也应反映出相互之间的差异。本文以宜兴市2009年和2017年土地利用现状数据为数据源，首先使用统一的分类标准提取用地类型中的3大类，通过不同大小的单元划分尝试和结果分析，发现适用于该数据的网格尺度大小；然后基于自然间断点分级法进行分级范围划定，对宜兴市三类用地类型的分布和变化趋势进行综合分析，较为真实地反映了宜兴市用地情况；最后通过选用合适的空间尺度和分级范围划定方法，进而构建一个兼具操作性和科学性的土地利用数据网格化方法，为自然资源部门统筹管理和综合治理提供依据。 相似文献