覆盖近乎全球的30 m ASTER DEM已经对公众开放,为研究全球尺度问题提供了较好的数据基础,但其数据精度和质量在我国区域内存在较多不确定性。研究了利用全国1∶50000高程数据对ASTER DEM数据异常进行修补的技术路线,从而为实现利用多源...覆盖近乎全球的30 m ASTER DEM已经对公众开放,为研究全球尺度问题提供了较好的数据基础,但其数据精度和质量在我国区域内存在较多不确定性。研究了利用全国1∶50000高程数据对ASTER DEM数据异常进行修补的技术路线,从而为实现利用多源DEM数据更新现有数据提供质量与可靠性保证,也为我国构建全球基础DEM数据库提供了一种有效的参考。展开更多
Singhbhum Shear Zone (SSZ) is a geologically rich belt with structures like faults and folds being the distinctive features. Due to these characteristics this area has been an important centre of studies since past fe...Singhbhum Shear Zone (SSZ) is a geologically rich belt with structures like faults and folds being the distinctive features. Due to these characteristics this area has been an important centre of studies since past few decades. With the advent of Remote Sensing and GIS, it has been possible to study and interprete geological setting of any area in the laboratory itself without even visiting the field again and again. The present study aims to investigate the geology of the SSZ from ASTER DEM by observing the elevation, as-pect, texture, pattern etc of shaded relief images. This can prove to be an excellent supplementary information database for interpretations along with other data.展开更多
介绍了ASTER Global DEM数据和Google Earth影像特点,以及阐述通过定制与检查DEM数据、卫星影像下载与纠正、数据基准转换与投影变换、等高线生成与影像叠加四个环节来制作遥感影像地图的方法。结合工程实践经验,说明该方法适合于难以...介绍了ASTER Global DEM数据和Google Earth影像特点,以及阐述通过定制与检查DEM数据、卫星影像下载与纠正、数据基准转换与投影变换、等高线生成与影像叠加四个环节来制作遥感影像地图的方法。结合工程实践经验,说明该方法适合于难以获取基础地理信息的区域,能辅助电力工程的选址选线。展开更多
The topographical suitability assessment of human settlements(SAHS) creates a solid foundation for regional population distribution and socio-economic development. Local elevation range(LER) is an important factor tha...The topographical suitability assessment of human settlements(SAHS) creates a solid foundation for regional population distribution and socio-economic development. Local elevation range(LER) is an important factor that can be used to assess the suitability of different terrains for sustaining human settlements. However, current digital elevation model(DEM)-based LER products suffer from some challenges typically because of their subjectively selected neighborhood scales and coarser spatial resolution. In this study, we initially determined the optimal statistical window and then calculated the appropriate LER with the finer resolution data of the Advanced Spaceborne Thermal Emission and Reflection Radiometer Global DEM(ASTER GDEM) products for China. Then, the appropriate LER was used to evaluate the topographical SAHS and its correlations with the national gridded population distribution(1 km × 1 km) in 2010. The results show that the optimal statistical window for calculating a 1 arc-second(about 30 m) resolution GDEM LER for China can be determined using a 51 × 51 grid unit(width × height) within a rectangular neighborhood, corresponding to an area of about 2.34 km^2. Secondly, the LER values in the southern and western China were greater than those of the north and east, showing a trend which consistently reflects the general spatial features of landforms. Finally, the relationship between GDEM LER and population density was highly correlated with the R^2 value of 0.81. It showed that 85.22% of the Chinese population was located in areas where the LER is lower than 500 m. The topographically suitable area within China decreased from the southeastern coastal zone towards the northwestern inland areas due to transition from plains and basins to plateaus and mountains. The total area of moderate to high suitable level was 423.84 × 10~4 km^2, or 44.15% of the total land area, with 88.17% of the national population. Our study demonstrates the usefulness of appropriate LER in evaluating the topographical SAHS as well as its significant impact on population distribution.展开更多
Digital Elevation Models (DEMs) depict the configuration of the earth surface and are being applied in many areas in earth and environmental sciences. In this study, the accuracy of the Advanced Land Observing Satelli...Digital Elevation Models (DEMs) depict the configuration of the earth surface and are being applied in many areas in earth and environmental sciences. In this study, the accuracy of the Advanced Land Observing Satellite World 3D Digital Surface Model version 2.1 (ALOS W3D30), the Shuttle Radar Topography Mission Digital Elevation Model version 3.0 (SRTM30) and the Advanced Space borne Thermal Emission and Reflection Radiometer Global DEM version 2.0 (ASTER GDEM2) was statistically assessed using high accuracy GPS survey data. Root-Mean-Square errors of ~5.40 m, ~7.47 m and ~20.03 m were obtained for ALOS W3D30, SRTM30 and ASTER GDEM2 respectively. In further analyses, we discovered that ALOS W3D30 and SRTM30 were much more accurate in regions where the height intervals were within 201 m - 400 m and >801 m. ALOS W3D30 proved to be the most accurate DEM that best represents the topography of the earth’s surface and could be used for some earth and environmental applications in Nigeria. We recommend that this study should serve as a guide in the use of any of these DEMs for earth and environmental applications in Nigeria.展开更多
Digital Elevation Models (DEMs) provide one of the most useful digital datasets for a wide range of users. Both the Shuttle Radar Topographic Mission (STRM V.4.1) topography and the Advanced Spaceborne Thermal Emissio...Digital Elevation Models (DEMs) provide one of the most useful digital datasets for a wide range of users. Both the Shuttle Radar Topographic Mission (STRM V.4.1) topography and the Advanced Spaceborne Thermal Emission and Reflection Radiometer Global Digital Elevation Model (ASTER-GDEM V.2) have been widely used in geomorphology, hydrology, tectonic, and others since they were made access to the public. The magnitude of vertical errors of two near-global DEMs—SRTM and ASTER-GDEM is compared and validated against a reference DEM which has a relatively high precision of 1:25,000 scale constructed from topographical map. Moreover, the reference DEM, ASTER-GDEM and SRTM were used as basic topographic data to extract some Morphometric index. The parameters like slope and shaded reflectance maps, were derived from the elevation distribution to provide a more sensitive indication of DEM quality. A square area in the North East of Tunisia was selected as a case study to test and evaluate the elevation accuracy of ASTER-GDEM and SRTM. The relative accuracy approach and absolute accuracy were adopted to evaluate global DEMs. The comparisons show that SRTM overestimates and ASTER-GDEM underestimates elevations, both DEMs can be used to extract the elevations of required geometric data,?i.e.?sub watershed boundaries, drainage information and cross sections. However, small errors still exist in. The lower root mean square errors values indicate that SRTM is comparatively more accurate than ASTER-GDEM.展开更多
文摘覆盖近乎全球的30 m ASTER DEM已经对公众开放,为研究全球尺度问题提供了较好的数据基础,但其数据精度和质量在我国区域内存在较多不确定性。研究了利用全国1∶50000高程数据对ASTER DEM数据异常进行修补的技术路线,从而为实现利用多源DEM数据更新现有数据提供质量与可靠性保证,也为我国构建全球基础DEM数据库提供了一种有效的参考。
文摘Singhbhum Shear Zone (SSZ) is a geologically rich belt with structures like faults and folds being the distinctive features. Due to these characteristics this area has been an important centre of studies since past few decades. With the advent of Remote Sensing and GIS, it has been possible to study and interprete geological setting of any area in the laboratory itself without even visiting the field again and again. The present study aims to investigate the geology of the SSZ from ASTER DEM by observing the elevation, as-pect, texture, pattern etc of shaded relief images. This can prove to be an excellent supplementary information database for interpretations along with other data.
文摘介绍了ASTER Global DEM数据和Google Earth影像特点,以及阐述通过定制与检查DEM数据、卫星影像下载与纠正、数据基准转换与投影变换、等高线生成与影像叠加四个环节来制作遥感影像地图的方法。结合工程实践经验,说明该方法适合于难以获取基础地理信息的区域,能辅助电力工程的选址选线。
基金supported by the National Key Research and Development Program (Grand No. 2016YFC0503506)the National Natural Science Foundation of China (Grand No. 41430861)
文摘The topographical suitability assessment of human settlements(SAHS) creates a solid foundation for regional population distribution and socio-economic development. Local elevation range(LER) is an important factor that can be used to assess the suitability of different terrains for sustaining human settlements. However, current digital elevation model(DEM)-based LER products suffer from some challenges typically because of their subjectively selected neighborhood scales and coarser spatial resolution. In this study, we initially determined the optimal statistical window and then calculated the appropriate LER with the finer resolution data of the Advanced Spaceborne Thermal Emission and Reflection Radiometer Global DEM(ASTER GDEM) products for China. Then, the appropriate LER was used to evaluate the topographical SAHS and its correlations with the national gridded population distribution(1 km × 1 km) in 2010. The results show that the optimal statistical window for calculating a 1 arc-second(about 30 m) resolution GDEM LER for China can be determined using a 51 × 51 grid unit(width × height) within a rectangular neighborhood, corresponding to an area of about 2.34 km^2. Secondly, the LER values in the southern and western China were greater than those of the north and east, showing a trend which consistently reflects the general spatial features of landforms. Finally, the relationship between GDEM LER and population density was highly correlated with the R^2 value of 0.81. It showed that 85.22% of the Chinese population was located in areas where the LER is lower than 500 m. The topographically suitable area within China decreased from the southeastern coastal zone towards the northwestern inland areas due to transition from plains and basins to plateaus and mountains. The total area of moderate to high suitable level was 423.84 × 10~4 km^2, or 44.15% of the total land area, with 88.17% of the national population. Our study demonstrates the usefulness of appropriate LER in evaluating the topographical SAHS as well as its significant impact on population distribution.
文摘Digital Elevation Models (DEMs) depict the configuration of the earth surface and are being applied in many areas in earth and environmental sciences. In this study, the accuracy of the Advanced Land Observing Satellite World 3D Digital Surface Model version 2.1 (ALOS W3D30), the Shuttle Radar Topography Mission Digital Elevation Model version 3.0 (SRTM30) and the Advanced Space borne Thermal Emission and Reflection Radiometer Global DEM version 2.0 (ASTER GDEM2) was statistically assessed using high accuracy GPS survey data. Root-Mean-Square errors of ~5.40 m, ~7.47 m and ~20.03 m were obtained for ALOS W3D30, SRTM30 and ASTER GDEM2 respectively. In further analyses, we discovered that ALOS W3D30 and SRTM30 were much more accurate in regions where the height intervals were within 201 m - 400 m and >801 m. ALOS W3D30 proved to be the most accurate DEM that best represents the topography of the earth’s surface and could be used for some earth and environmental applications in Nigeria. We recommend that this study should serve as a guide in the use of any of these DEMs for earth and environmental applications in Nigeria.
文摘Digital Elevation Models (DEMs) provide one of the most useful digital datasets for a wide range of users. Both the Shuttle Radar Topographic Mission (STRM V.4.1) topography and the Advanced Spaceborne Thermal Emission and Reflection Radiometer Global Digital Elevation Model (ASTER-GDEM V.2) have been widely used in geomorphology, hydrology, tectonic, and others since they were made access to the public. The magnitude of vertical errors of two near-global DEMs—SRTM and ASTER-GDEM is compared and validated against a reference DEM which has a relatively high precision of 1:25,000 scale constructed from topographical map. Moreover, the reference DEM, ASTER-GDEM and SRTM were used as basic topographic data to extract some Morphometric index. The parameters like slope and shaded reflectance maps, were derived from the elevation distribution to provide a more sensitive indication of DEM quality. A square area in the North East of Tunisia was selected as a case study to test and evaluate the elevation accuracy of ASTER-GDEM and SRTM. The relative accuracy approach and absolute accuracy were adopted to evaluate global DEMs. The comparisons show that SRTM overestimates and ASTER-GDEM underestimates elevations, both DEMs can be used to extract the elevations of required geometric data,?i.e.?sub watershed boundaries, drainage information and cross sections. However, small errors still exist in. The lower root mean square errors values indicate that SRTM is comparatively more accurate than ASTER-GDEM.
