三维GIS技术在断面测量中的应用     

许懿娜  闵世平  缪志修  王玮 《测绘科学》2013,38(4)

本文针对常规基于二维矢量数据和高分辨率影像的断面采集方式在直观性、数据源等方面的不足,引入三维GIS技术,利用相关基础地理数据构建三维地理环境,设计了一套三维地理环境下的断面数据采集技术流程,并在此基础上研制了一个软件平台.实际工程应用显示,该平台不仅可以满足铁路勘测设计应用,还具有可视化、批量化断面采集和检查能力,能够提高断面采集工作效率,减轻内业工作强度.  相似文献   

Terrain radiometric calibration of airborne UAVSAR for forested area     

Xiaoguang CHENG  Naiara PINTO  Jianya GONG 《地球空间信息科学学报》2013,16(4):229-240

In the field of biomass estimation, terrain radiometric calibration of airborne polarimetric SAR data for forested areas is an urgent problem. Illuminated area correction of σ -naught could not completely remove terrain features. Inspired by Small and Shimada, this paper tested gamma-naught on one mountainous forested area using airborne Uninhabited Aerial Vehicle Synthetic Aperture Radar data and found it could remove most terrain features. However, a systematic increasing trend from far range to near range is found in airborne SAR cases. This paper made an attempt to use the relationship between distance to SAR sensor and γ-naught to calibrate γ -naught. Two quantitative evaluation methods are proposed. Experimental results demonstrate that variation of γ -naught can be constrained to a limited extent from near range to far range. Since this method is based on ground range images, it avoids complicated orthorectification.  相似文献   

Evaluation of modified four-component scattering power decomposition method over highly rugged glaciated terrain     

Gulab Singh  Y. Yamaguchi  S.-E. Park  Ram Avtar 《国际地球制图》2013,28(2):139-151

In recent years, there has been increased utilization of fully polarimetric synthetic aperture radar (POLSAR) data to study glaciated terrain features for glaciological and climate change modelling. This article is concerned with more accurate results and appropriate analysis of POLSAR data over a highly rugged glaciated area in Himalayan region. For this purpose, the modified Yamaguchi four-component scattering power decomposition (4-CSPD) method with a rotation concept of 3 × 3 coherency matrix [T] about line of sight is evaluated. It has been found that the modified Yamaguchi 4-CSPD method significantly improved the decomposition results as compared with the original 4-CSPD by minimizing the cross-polarized Horizontal-Vertical (HV) components. This modified 4-CSPD leads to enhancement in the double bounce scattering and surface scattering components and also avoids the overestimation problem in the volume scattering component as compared with the original 4-CSPD from the sloped terrain. The significant reductions of the negative power occurrence in the surface scattering (3.9%) and the double bounce scattering (19.7%) components have also been noticed as compared with the original 4-CSPD method over the glaciated area in this part of the Indian Himalaya.  相似文献   

Semantic calibration of digital terrain analysis scale     

Bradley A. Miller 《制图学和地理信息科学》2013,40(2):166-176

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INTERANNUAL TO INTERDECADAL VARIATIONS OF THE REGIONALIZED SURFACE CLIMATE OF THE UNITED STATES AND RELATIONSHIPS TO GENERALIZED FLOW PARAMETERS     

Anthony J. Vega  Chung-Hsiung Sui  Ka-Ming Lau 《自然地理学》2013,34(4):271-291

This analysis attempts to discern primary causes of interannual and interdecadal climate variations for precipitation and temperature regions of the conterminous United States. Varimax rotated principal components analysis of annual climate division data is used in the derivation of nine precipitation and five temperature regions. Each region's time series is examined for underlying linear trends, representing long-term climate change, and tests for variance changes, to determine regional climate variability shifts. The first six precipitation components, representing the entire eastern half of the country and the Northwest, displayed significant temporal increases. Of these, four displayed significant increases in interannual variability through time. For temperature, only the Southwestern region showed a significant change (increase) through time. However, significant reductions in temperature variability were confirmed for three regions. To determine the causes of the derived climate shifts, correlation analysis was performed with various atmospheric teleconnection indices. Precipitation trends are most strongly associated with variations in the Southern Oscillation Index (SOI) at the interannual time scale while interdecadal variations are associated more with variations in the Pacific/North American (PNA) teleconnection. Both interannual and interdecadal variations of regional temperature are most strongly related to the PNA, except for the Southwest, which showed a significant correlation to the SOI. This suggests that El Niño/Southern Oscillation (ENSO) events are the source for much of the precipitation change evident in the eastern and Northwestern United States and temperature change in the Southwest. [Key words: climate change, precipitation, temperature, El Niño, Southern Oscillation, United States climate.]  相似文献   

Morphometric Comparisons Between Rogen Terrain and Hummocky Terrain     

《自然地理学》2013,34(4):319-336

Visual interpretation of aerial photography suggests that certain geomorphological similarities exist between the hummocky terrain of central Alberta, Canada, and the Rogen terrain of Nunavut, Canada. This study statistically compares the two landform types based on measures of depression shapes and ridge orientations. Comparison of depression shapes indicates that two of three sample areas chosen from the hummocky terrain study area are statistically similar to those of the Rogen terrain study area. Analysis of ridge orientations indicates the ridge crests from two of three hummocky terrain sample areas, and ridge crests from within the Rogen terrain study site all exhibit a preferred trend. Variability in the process of formation may explain why only particular areas throughout the hummocky terrain exhibit patterns similar to the Rogen terrain and others do not. Statistical similarities in two-dimensional form between the hummocky terrain of central Alberta and the Rogen terrain of the Northwest Territories however, suggest that these landforms may have a common or similar origin.  相似文献   

汶川地震诱发山地斜坡震动的地形放大效应     

罗永红  王运生 《山地学报》2013,31(2)

汶川地震诱发大量山地斜坡次生灾害具有明显的地形分布特征,对其地形放大效应研究具有重要的理论及实际意义.斜坡震害调查表明,宏观地貌单元对次生地质灾害的发育类型具有控制作用,中高山区以大中型滑坡、崩塌为主,低山及丘陵区以山体震裂、小型崩塌为主;峡谷形态对次生地质灾害的发育密度具有明显影响,其中“V”型峡谷发育密度高于“U”型峡谷;单薄山脊、条形山体、坡型转折部位、凸出地形等微地貌地形放大效应明显.监测显示,不同方向水平分量地震波峰值(PHA)相差可达10余倍,研究表明:地形尺寸与地震波波长的耦合作用使得地震动水平分量放大显著.  相似文献   

Terrain complexity and uncertainties in grid‐based digital terrain analysis     

Qiming Zhou  Xuejun Liu  Yizhong Sun 《International journal of geographical information science》2013,27(10):1137-1147

The objective of this research is to study the relationship between terrain complexity and terrain analysis results from grid‐based digital elevation models (DEMs). The impact of terrain complexity represented by terrain steepness and orientation on derived parameters such as slope and aspect has been analysed. Experiments have been conducted to quantify the uncertainties created by digital terrain analysis algorithms. The test results show that (a) the RMSE of derived slope and aspect is negatively correlated with slope steepness; (b) the RMSE of derived aspect is more sensitive to terrain complexity than that of derived slope; and (c) the uncertainties in derived slope and aspect tend to be found in flatter areas, and decrease with increasing terrain complexity. The study shows that although primary surface parameters can be well defined mathematically, the implementation of those mathematical models in a GIS environment may generate considerable uncertainties related to terrain complexity. In general, when terrain is rugged with steep slopes, the uncertainty of derived parameters is quite minimal. While in flatter areas, the DEM‐based derivatives, particularly the aspect, may contain a great amount of uncertainty, causing significant limitation in applying the analytical results.  相似文献   

Computation of the third‐order partial derivatives from a digital elevation model     

Igor V. Florinsky 《International journal of geographical information science》2013,27(2):213-231

Loci of extreme curvature of the topographic surface may be defined by the derivation function (T) depending on the first‐, second‐, and third‐order partial derivatives of elevation. The loci may partially describe ridge and thalweg lines. The first‐ and second‐order partial derivatives are commonly calculated from a digital elevation model (DEM) by fitting the second‐order polynomial to a 3×3 window. This approach cannot be used to compute the third‐order partial derivatives and T. We deduced formulae to estimate the first‐, second‐, and third‐order partial derivatives from a DEM fitting the third‐order polynomial to a 5×5 window. The polynomial is approximated to elevation values of the window. This leads to a local denoising that may enhance calculations. Under the same grid size of a DEM and root mean square error (RMSE) of elevation, calculation of the second‐order partial derivatives by the method developed results in significantly lower RMSE of the derivatives than that using the second‐order polynomial and the 3×3 window. An RMSE expression for the derivation function is deduced. The method proposed can be applied to derive any local topographic variable, such as slope gradient, aspect, curvatures, and T. Treatment of a DEM by the method developed demonstrated that T mapping may not substitute regional logistic algorithms to detect ridge/thalweg networks. However, the third‐order partial derivatives of elevation can be used in digital terrain analysis, particularly, in landform classifications.  相似文献   

Simultaneous computation of total viewshed on large high resolution grids     

S. Tabik  E.L Zapata  L.F Romero 《International journal of geographical information science》2013,27(4):804-814

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