共查询到20条相似文献，搜索用时 15 毫秒
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全面评价数字高程模型（digital elevation model，DEM）升尺度转换方法的精度，有助于合理选择DEM升尺度转换方法，掌握DEM尺度转换规律及构建新的DEM升尺度转换模型。然而目前关于DEM精度评价的研究成果还难以达到实际应用的要求，从全新的视角寻找客观、高效的DEM升尺度转换结果的精度评价方法仍有待研究。基于地球表面接收太阳辐射的分布特性，提出基于能量因子的DEM精度评价方法，应用于不同DEM升尺度转换方法的精度评价中。基于现有的精度评定与质量评价方法，构建定性与定量分析相结合的综合评价方法，以验证基于能量因子的精度评价方法的合理性和有效性。实验结果表明，基于能量因子的精度评价方法原理简单、操作方便，能够反映升尺度转换后DEM地形空间遮蔽关系的变化情况。该方法为DEM升尺度转换结果的精度评价提供了新的思路和方向，对DEM在定量遥感建模与山区地表生态参量反演等方面的应用具有一定的借鉴意义。 相似文献
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Assessment of Dem Quality for Characterizing Surface Roughness Using Close Range Digital Photogrammetry 总被引：2，自引：0，他引：2
This paper presents a procedure for assessing the quality of a digital elevation model (DEM) which has been applied to the output of a normalized cross correlation based stereomatching algorithm. Using semimetric photography of natural gravel river bed surfaces acquired in the field, digital photogrammetry was used to extract DEMs automatically for use in characterizing surface roughness properties. The procedure for assessing DEM quality involves examination of (i) ortho-images, to provide a qualitative check on stereomatching performance; (ii) DEM collection statistics which quantify the percentage of correctly matched pixels as a function of those interpolated; and (iii) height differences between check points, measured using independent field survey, and corresponding DEM points. The concepts of precision, accuracy and reliability are defined in the context of DEM quality assessment and methods are outlined which can be used to assess these variables. The assessment is conducted for two adjacent stereopairs with similar characteristics, considering the effects of both DEM collection parameters and different lens models upon DEM quality. Results show that digital photogrammetry, in conjunction with independent field survey, can be used successfully for extracting high resolution, small scale DEMs from natural gravel surfaces. Components (i) and (ii) of the quality assessment suggest the need to optimize DEM collection parameters, although the effects of not using a properly specified lens model were minimal at this scale. Method (iii) showed that increasing stereomatching success does not necessarily lead to more accurately estimated DEM points. However, the use of method (iii) remained difficult because of the scale of the photogrammetric application being used; check point positioning within the photogrammetric co-ordinate system was only possible to ±10 mm which, for a gravel bed surface, was associated with elevation variance of a similar, sometimes greater, magnitude. The next stage of this research will require the use of higher quality check data, possibly from laser profiling. 相似文献
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利用星载重复轨道合成孔径雷达干涉测量InSAR技术获取数字高程模型(DEM),无法避免大气延迟效应的影响。InSAR大气校正的方法很多,但在DEM获取方面的大气校正研究却非常少见。本文研究星载重轨InSAR生产DEM时利用大气数值模式WRF(Weather Research and Forecasting model)得到的水汽结果进行大气校正的问题,重点讨论大气校正的策略,包括WRF模式设置和大气校正时机的选择,简要介绍了基于WRF运算结果的大气校正方法。利用Terra SAR-X数据进行实验,检验了所提出方法的有效性,证明了在干涉相位解缠前进行大气校正,比在相位解缠后进行的效果更好。将所提出方法应用于多基线、多波段InSAR干涉结果融合中,实验结果表明大气校正能够有效降低误差,对于相干性较高的地区效果更好。 相似文献
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This paper compares the accuracy of Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) Global Digital Elevation Model (GDEM), Shuttle Radar Topography Mission (SRTM) C-band and German Aerospace Centre (DLR)-SRTM X-band digital elevation models (DEMs) with the Ziyuan 3 (ZY-3) stereoscopic DEM and ground control points (GCPs). To date, the horizontal error of these DEMs has received little attention in accuracy assessments. Using the ZY-3 DEM as reference, this study examines (1) the horizontal offset between the three DEMs and the reference DEM using the normalised cross-correlation method, (2) the vertical accuracy of those DEMs using kinematic GPS data and (3) the relationship between the three DEMs and the reference ZY-3 DEM. The results show that the SRTM and DLR-SRTM have greater vertical accuracy after applying horizontal offset correction, whereas the vertical accuracy of the ASTER GDEM is less than the other two DEMs. These methods and results can be useful for researchers who use DEMs for various applications. 相似文献
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为了降低误差母体分布的非正态性和较少采样数对DEM误差方差置信区间估计精度的影响,发展了改进的非参数估计法（M-NPM）。以机载激光扫描仪获取的6个不同区域的DEM数据为研究对象,基于交叉验证法分别获取了三组近似正态分布和三组非正态分布的DEM误差数据,并将其作为试验母体。从母体中随机采样,基于M-NPM获取方差置信度为95%的置信区间,借助母体进行精度验证,并与NPM结果比较。结果分析表明,当采样数小于40时,两种方法的模拟结果精度均受误差母体分布的影响,但M-NPM受影响的程度小于NPM;相比误差母体正态分布,当误差母体非正态分布时,M-NPM的估计精度明显优于NPM;无论误差母体服从何种分布,采样总量为多少,M-NPM的精度始终高于NPM,但M-NPM较高的精度是以较宽的置信区间为代价的。 相似文献
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Evaluation of Information Loss in Digital Elevation Models With Digital Photogrammetric Systems 总被引：3，自引：0，他引：3
Y. D. Huang 《The Photogrammetric Record》2000,16(95):781-791
Information loss is caused when a surface is sampled with a finite interval, such as in the production of a digital elevation model (DEM). This information loss can become the dominant part of the error in a DEM. The ability to quantify information loss enables guidance to be provided for an appropriate choice of grid interval and better accuracy assessment for the DEM. With the use of digital photogrammetric systems, evaluation of information loss has become much easier. This paper describes three methods of evaluating information loss. An example is given of the method which is most appropriate for use with a digital photogrammetric system, based on rock cliff surface data and the VirtuoZo system. 相似文献
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研究山区地表水体信息OLI遥感数据去阴影自动提取方法,设计基于数字高程模型与指数提取的决策树分类方法,提高水体自动识别的精度。该方法选取改进的归一化水体指数、归一化植被指数、比值植被指数、主成分分析前3个分量以及波段之间的组合运算,并结合DEM构建决策树分类规则。综合采用单波段阈值、谱间关系、植被指数和水体指数阈值完成山体水体的去阴影识别研究,与计算机自动识别分类方法比较,其精度明显提高。结果表明,决策树分类方法在精度上明显高于常用的计算机自动分类方法,可以很好地被利用于OLI遥感数据水体信息的海量、大范围提取。 相似文献
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Loudi Yap Ludovic Houetchak Kandé Robert Nouayou Nasser Abdou Ngouh Marie Brigitte Makuate 《International Journal of Digital Earth》2019,12(5):500-524
Digital Elevation Models (DEMs) contain topographic relief data that are vital for many geoscience applications. This study relies on the vertical accuracy of publicly available latest high-resolution (30?m) global DEMs over Cameroon. These models are (1) the ALOS World 3D-30?m (AW3D30), (2) the Shuttle Radar Topography Mission 1 Arc-Second C-Band Global DEM (SRTM 1) and (3) the Advanced Spaceborne Thermal Emission and Reflection Global DEM Version 2 (ASTER GDEM 2). After matching their coordinate systems and datums, the horizontal positional accuracy evaluation was carried out and it shows that geolocation errors significantly influence the vertical accuracy of global DEMs. After this, the three models are compared among them, in order to access random and systematic effects in the elevation data each of them contains. Further, heights from 555 GPS/leveling points distributed all over Cameroon are compared to each DEM, for their vertical accuracy determination. Traditional and robust statistical measures, normality test, outlier detection and removal were used to describe the vertical quality of the DEMs. The test of the normality rejected the hypothesis of normal distribution for all tested global DEMs. Overall vertical accuracies obtained for the three models after georeferencing and gross error removal in terms of Root Mean Square (RMS) and Normalized Median Absolute Deviation (NMAD) are: AW3D30 (13.06?m and 7.75?m), SRTM 1 (13.25?m and 7.41?m) and ASTER GDEM 2 (18.87?m and 13.30?m). Other accuracy measures (MED, 68.3% quantile, 95% quantile) supply some evidence of the good quality of AW3D30 over Cameroon. Further, the effect of land cover and slope on DEM vertical accuracy was also analyzed. All models have proved to be worse in the areas dominated by forests and shrubs areas. SRTM 1 and AW3D30 are more resilient to the effects of the scattering objects respectively in forests and cultivated areas. The dependency of DEMs accuracy on the terrain roughness is evident. In all slope intervals, AW3D30 is performing better than SRTM 1 and ASTER GDEM 2 over Cameroon. AW3D30 is more representative of the external topography over Cameroon in comparison with two others datasets and SRTM 1 can be a serious alternative to AW3D30 for a range of DEM applications in Cameroon. 相似文献
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Xiaoping Du Huadong Guo Xiangtao Fan Junjie Zhu Zhenzhen Yan Qin Zhan 《International Journal of Digital Earth》2016,9(3):252-271
The frequency of coastal flood damages is expected to increase significantly during the twenty-first century as sea level rises in the coastal floodplain. Coastal digital elevation model (DEM) data describing coastal topography are essential for assessing future flood-related damages and understanding the impacts of sea-level rise. The Shuttle Radar Topography Mission (SRTM) and Advanced Spaceborne Thermal Emission and Reflection Radiometer Global Digital Elevation Model (ASTER GDEM) are currently the most accurate and freely available DEM data. However, an accuracy assessment specifically targeted at DEMs over low elevation coastal plains is lacking. The present study focuses on these areas to assess the vertical accuracy of SRTM and ASTER GDEM using Ice, Cloud, and land Elevation Satellite, Geoscience Laser Altimeter System (ICESat/GLAS) and Real Time Kinematic (RTK) Global Positioning System (GPS) field survey data. The findings show that DEM accuracy is much better than the mission specifications over coastal plains. In addition, optical remote sensing image analysis further reveals the relationship between DEM vertical accuracy and land cover in these areas. This study provides a systematic approach to assess the accuracy of DEMs in coastal zones, and the results highlight the limitations and potential of these DEMs in coastal applications. 相似文献
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《地理信息系统科学与遥感》2013,50(3):412-424
One of the problems in detecting occlusions when generating true ortho photos is false occlusion and false visibility caused by rolling terrain, and the resolution difference between the digital surface model (DSM) and the images. Published methods are plagued by unstable computation and have considerable noise. The paper presents a vector-based backward projection (VBP) method for detecting occlusions. First, the method projects vector polygons representing the surface of buildings to image space. Next, it derives their true coverage by judging the occupancy priority for the overlap. It then determines the visibility of building and digital elevation model (DEM) grids. Finally, it generates a true ortho image by differential rectification. In addition, this paper develops methods to keep all steps robust, such as dubious region growing methods for rasterization and judgment formulas for boundary noise elimination, which makes VBP practical. Experiments using the Z-Buffer method, the projection-ray-angle-based method and VBP with a typical image and DSM prove VBP has 100% detection accuracy, and is robust and efficient. 相似文献
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栅格DEM微地形分类是数字地形精细化应用的基础，基于规则化知识的栅格DEM微地形分类方法存在自动化程度低、分类残缺等问题。本文利用BP神经网络的优势构建了栅格DEM微地形分类的人工智能方法与实现途径。以山体部位分类为微地形分类典型样例进行试验验证与分析，试验结果表明，栅格DEM微地形分类的BP神经网络法较已有的地形因子叠加分析方法存在明显优势，不仅在流程上可避免烦琐的数据叠加分析过程，而且分类结果的完整性和错分率都得到有效改善；在山体部位分出的6种微地形中，冲积地对该方法适应性最强，准确率为100%，背坡的适应性最弱准确率为89.23%。 相似文献
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Accuracy assessment of lidar-derived digital elevation models 总被引：2，自引：0，他引：2
Despite the relatively high cost of airborne lidar-derived digital elevation models (DEMs), such products are usually presented without a satisfactory associated estimate of accuracy. For the most part, DEM accuracy estimates are typically provided by comparing lidar heights against a finite sample of check point coordinates from an independent source of higher accuracy, supposing a normal distribution of the derived height differences or errors. This paper proposes a new methodology to assess the vertical accuracy of lidar DEMs using confidence intervals constructed from a finite sample of errors computed at check points. A non-parametric approach has been tested where no particular error distribution is assumed, making the proposed methodology especially applicable to non-normal error distributions of the type usually found in DEMs derived from lidar. The performance of the proposed model was experimentally validated using Monte Carlo simulation on 18 vertical error data-sets. Fifteen of these data-sets were computed from original lidar data provided by the International Society for Photogrammetry and Remote Sensing Working Group III/3, using their respective filtered reference data as ground truth. The three remaining data-sets were provided by the Natural Environment Research Council's Airborne Research and Survey Facility lidar system, together with check points acquired using high precision kinematic GPS. The results proved promising, the proposed models reproducing the statistical behaviour of vertical errors of lidar using a favourable number of check points, even in the cases of data-sets with non-normally distributed residuals. This research can therefore be considered as a potentially important step towards improving the quality control of lidar-derived DEMs. 相似文献
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刘二永 《测绘与空间地理信息》2013,(12):1-3,7
基于柯西-施瓦茨不等式,本文提出了一种新的误差3维可视化方法,用于描述DEM双线性插值的误差传播。该模型给DEM用户提供了围绕量测DEM的一个置信空间,真实的DEM将以大于预定的置信水平包含在这个置信空间里。该模型可以使DEM用户直观地了解DEM双线性插值的误差传播情况,从而使对DEM适用性的决策更为准确。 相似文献
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Digital elevation models (DEMs) are essential to various applications in topography, geomorphology, hydrology, and ecology. The Shuttle Radar Topographic Mission (SRTM) DEM data set is one of the most complete and most widely used DEM data sets; it provides accurate information on elevations over bare land areas. However, the accuracy of SRTM data over vegetated mountain areas is relatively low as a result of the high relief and the penetration limitation of the C-band used for obtaining global DEM products. The objective of this study is to assess the performance of SRTM DEMs and correct them over vegetated mountain areas with small-footprint airborne Light Detection and Ranging (Lidar) data, which can develop elevation products and vegetation products [e.g., vegetation height, Leaf Area Index (LAI)] of high accuracy. The assessing results show that SRTM elevations are systematically higher than those of the actual land surfaces over vegetated mountain areas. The mean difference between SRTM DEM and Lidar DEM increases with vegetation height, whereas the standard deviation of the difference increases with slope. To improve the accuracy of SRTM DEM over vegetated mountain areas, a regression model between the SRTM elevation bias and vegetation height, LAI, and slope was developed based on one control site. Without changing any coefficients, this model was proved to be applicable in all the nine study sites, which have various topography and vegetation conditions. The mean bias of the corrected SRTM DEM at the nine study sites using this model (absolute value) is 89% smaller than that of the original SRTM DEM, and the standard deviation of the corrected SRTM elevation bias is 11% smaller. 相似文献
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以福建九龙江口海岸带DEM数据构建为实例,介绍了基于ArcGIS软件综合陆域、海域以及海陆交界处干出滩数据,构建海岸带DEM并进行精度评估的方法。精度评估结果显示所构建的数字高程模型是满足国家DEM构建相关标准精度要求,从而为GIS在海岸带资源信息化综合管理中应用提供了技术支撑。 相似文献
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高精度曲面建模的三维地形可视化研究 总被引：3，自引：1，他引：2
根据高精度曲面建模理论(HASM)中曲面单元算法的特点,提出基于视点的多分辨率LOD实时生成算法。该方法通过对规则格网的DEM数据进行划分,以单元分片为基本单位对DEM数据进行组织。根据各曲面单元与视点的相对关系,以不同间距对曲面单元进行内插,实时重建视景内的三维地形。在实时显示过程中,对硬盘中的数据进行实时读取,采用多线程技术对图像渲染操作进行处理,实现了对DEM数据的实时计算、动态显示。该方法无需对规则格网DEM数据建立空间层次组织结构,在对虚拟地形进行实时漫游过程中,存储空间占用少,不受数据规模的影响。 相似文献
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机载激光雷达技术(LiDAR)作为一项先进的遥感技术,是植被覆盖区DEM获取的重要手段之一,而不同地形坡度条件及点云密度对DEM产品质量有重要影响。本文以辽宁省某市的机载LiDAR数据为基础,选取5种不同地形坡度的点云数据,通过随机、等间距及基于曲率3种不同的点云抽稀方法,按照点云保留率为80%、60%、40%、20%和10%共5个不同梯度的抽稀倍数对原始点云进行抽稀简化处理,生成与之对应的DEM并对其进行精度评价,以此研究地形坡度、点云抽稀方法、抽稀倍数对DEM精度的影响。结果表明,DEM精度与地形坡度呈负相关关系,即RMSE随地形坡度升高不断增加;基于曲率的抽稀方法在地形坡度＞30°时,相较于其他两种方法RMSE较小,具有明显优势;40%的点云保留率是平衡DEM精度与数据存储效率的一个节点,当点云保留率<40%时,DEM的高程RMSE会迅速增大。该研究对于利用机载LiDAR进行大范围DEM生产具有一定的指导和借鉴意义。 相似文献