基于RTK的高程数据对比分析

以内蒙古扎赉特旗吉日根林场为研究区,通过采集区内高精度的RTK高程数据作为参考,比较区域内的Google Earth、SRTM-1和ASTER GDEM V2高程数据的垂直精度。研究结果表明,Google Earth和ASTER GDEM V2数据在地形起伏度小的区域有明显抖动。坡度与地貌不同时,SRTM-1数据的绝对均值误差、标准差和均方根误差均较小。相较而言,SRTM-1表达地形更为准确,和采集的RTK实验点基本相同。     

Estimation of winter wheat biomass based on remote sensing data at various spatial and spectral resolutions

Biomass can indicate plant growth status, so it is an important index for plant growth monitoring. This paper focused on the methodology of estimating the winter wheat biomass based on hyperspectral field data, including the LANDSAT TM and EOS MODIS images. In order to develop the method of retrieving the wheat biomass from remote sensed data, routine field measurements were initiated during periods when the LANDSAT satellite passed over the study region. In the course of the experiment, five LANDSAT TM images were acquired respectively at early erecting stage, jointing stage, earring stage, flowering stage and grain-filling stage of the winter wheat, and the wheat biomass was measured at each stage. Based on the TM and MODIS images, spectral indices such as NDVI, RDVI, EVI, MSAVI, SIPI and NDWI were calculated. At the same time, the hyperspectral field data was used to compute the normalized difference in spectral indices, red-edge parameters, spectral absorption, and reflection feature parameters. Then the correlation coefficients between the wheat biomass and spectral parameters of the experiment sites were computed. According to the correlation coefficients, the optimal spectral parameters for estimating the wheat biomass were determined. The bestfitting method was employed to build the relationship models between the wheat biomass and the optimal spectral parameters. Finally, the models were used to estimate the wheat biomass based on the TM and MODIS data. The maximum RMSE of estimated biomass was 66.403 g/m².     

Fortran IV program for grey-level mapping of spatial data

Afortran iv computer program for grey-level mapping of spatial data using a CDC 6600 is described. The program produces maps for irregularly distributed data in as many as 10 intensity levels which are displayed in grey tones by a lineprinter. Unlimited map size and unrestricted data input provide for as many as 5000 data points per 13-in.-wide strip of map. The program is easily modified for other installations. Examples are given of geochemical analyses of stream sediments in Northern Ireland.     

Accounting for exhaustive secondary data into the mapping of water table elevation

This paper presents the incorporation of a digital elevation model into the spatial prediction of water table elevation in Mazandaran province (Iran) using a range of interpolation techniques. The multivariate methods used are: linear regression (LR), cokriging (COK), kriging with an external drift (KED) and regression kriging (RK). The analysis is performed on 3 years (1987, 1997 and 2007) of water table elevation data from about 260 monitoring wells. Prediction performances of the different algorithms are compared with two univariate techniques, i.e. inverse distance weighting and ordinary kriging (OK), through cross validation and examination of the consistency of the generated maps with the natural phenomena. Significantly smaller prediction errors are obtained for four multivariate algorithms but, in particular, KED and RK outperform LR and COK for 3 years. The results show the potential for using elevation for a more precise mapping of water table elevation.     

Estimating spatial correlation structures based on CPT data

Spatial correlation structures are usually used while modelling inherent uncertainty associated with soil properties. To retrieve this information a sufficient number of measurements and equal intervals between measurements or samples are always required. However, in practice, it is not usual to conduct site investigation in that way subject to a limited budget. Therefore, it is of interest to understand the possible bias created by using samples with unequal intervals. This research focuses on estimating the vertical spatial correlation structures of cone penetration tests (CPT) data conducted at a liquefaction site in Taiwan. The appropriate fitting range used in calibrating the correlation model is also discussed. The results show that cone tip resistance has larger correlation distances than that of sleeve friction. The estimated correlation distances of the CPT profiles are similar while using an equal sampling interval within a certain fitting range (denoted as the critical interval of measurements in this research). The results indicate that the effect of using different curve-fitting ranges is relatively insignificant for correlation distances of sleeve friction, whereas the correlation distances of cone tip resistance are more sensitive to different curve-fitting ranges. Moreover, the mean values of correlation distances are more constant for the equal sampling interval cases than for the unequal interval cases.     

基于GIS空间数据的滑坡SPH粒子模型研究

针对光滑粒子流体动力学方法（SPH）在滑坡模拟中建立粒子模型的难题,提出了基于地理信息系统（GIS）栅格数据的粒子排列与插入方法。根据该方法,建立了滑坡SPH粒子模型及相关粒子生成程序,进一步以结合摩尔-库仑破坏准则的SPH宾汉流体模型为核心,实现了运用SPH方法模拟滑坡破坏后三维运动的过程。该SPH模型在对唐家山滑坡的模拟中得到了验证,并预测了金坪子滑坡破坏后的影响范围。结果表明：基于GIS空间数据的滑坡SPH粒子模型具有可行性与良好的适用性。以GIS数据库为基础,开展滑坡灾害的模拟研究,将大大提高对滑坡等地质灾害的仿真分析,为滑坡灾害的预测与防治提供参考。     

基于Global Mapper的测绘图形数据转换

Global Mapper支持多种格式的光栅、高程、矢量数据的读取与输出,并内置多种坐标投影方式。尝试挖掘其支持多种数据格式、多种投影模式的功能,快速实现测绘图形数据的转换。通过设置当前工作空间的坐标投影模式,然后打开任何其支持的、含有坐标投影信息的数据,所有数据均自动转换成当前的投影模式,最后将文件输出（另存为）为所需的格式,即可快速完成数据转换。转换的内容主要包括不同格式的DTM(Digital Terrain Model,数字地面模型)数据转换、相同格式但不同坐标投影之间的相互转换,以及卫星影像配准等     

基于ICESat数据的南极冰盖DEM插值方法比较及精度分析

南极数字高程模型(DEM)是从事南极地学和环境变化研究的基础. 内插是建立数字高程模型的重要技术点, 插值方法有多种, 根据不同的适用情况, 不同的插值方法各有优劣. 利用克里格、 距离反权、 三角网剖分、 最小曲率以及移动平均5种插值方法分别建立南极冰盖小范围区域的DEM, 通过抽取部分观测数据作为验证值对各插值方法进行了比较. 结果表明: 克里格插值方法的可靠性最好, 稳定性最高. 然后, 利用克里格插值方法, 基于ICESat测高卫星的GLA12数据建立了南极冰盖的DEM. 由于南极大陆实测数据有限, 缺乏对DEM的检核. 为了分析所建DEM的可靠性, 利用中国南极内陆冰盖考察所采集的GPS实测数据, 对所建立的DEM进行了验证分析. 结果显示, DEM在坡度较缓的南极内陆冰盖区域精度较高, 符合度在3 m以内; 距离卫星轨道越近的区域精度越高, 可达到1 m 以内. 在坡度较大, 高程变化较为显著的区域如沿海地区, 精度较低, 差距最大的点超过40 m.     

Google Earth高程数据精度分析及在地震勘探中的应用

地震勘探勘查区往往位于偏远地区,已知地形资料较少。 Google Earth（简称GE）采用的数字高程模型数据为SRTM,精度较高。笔者在批量提取GE高程数据的基础上,分别对山区和平原地区的GE高程数据的精度进行了分析。结果表明,无论是在山区还是平原地区,GE高程数据均与地表实际高程基本一致;在平原地区的精度高于山区;GE高程数据可以满足等高线生成和观测系统参数分析的需要。     

利用ERS-1/2数据生成西藏羊八井地区数字高程模型及其精度评价

干涉合成孔径雷达(InSAR)数据已被证明能生成精确的数字高程模型。本文利用欧空局2颗卫星ERS-1/2对西藏羊八井地区成像所获取的相隔仅1天2幅SAR复数影像作了干涉处理和分析,生成了DEM,并与1∶5万DEM比较,对干涉DEM的精度作了评价,并分析了其潜在的制约因素。试验证明,在西藏地区的研究中,InSAR是一种非常有效的手段,不仅可用于地图制图,而且在地球动力学、地貌环境变化等领域也有巨大的潜力。     

Accounting for spatial patterns of multiple geological data sets in geological thematic mapping using GIS-based spatial analysis

This paper presents a Geographic Information System (GIS)-based spatial analysis scheme to account for spatial patterns and association in geological thematic mapping with multiple geological data sets. The multi-buffer zone analysis, the main part of the present study, was addressed to reveal the spatial pattern around geological source primitives and statistical analysis based on a contingency table was performed to extract information for the assessment of an integrated layer. Mineral potential mapping using multiple geological data sets from Ogdong in Korea was carried out to illustrate application of this methodology. The results obtained from the case study indicated that some geochemical elements and residual magnetic anomaly dominantly affected spatial patterns of the mineral potential map in the study area and the dominant classes of input data layers were also extracted. This information on spatial patterns of multiple geological data sets around mines could be used as effective evidences for the interpretation of the integrated layer within GIS.     

Evaluating the sensitivity of DRASTIC using different data sources,interpretations and mapping approaches

When used in a comprehensive risk assessment framework, aquifer vulnerability maps are a tool to identify the relative susceptibility of the groundwater from sources of contamination at the land surface. The DRASTIC method was designed for use over large areas with a wide variety of geological and hydrogeologic settings as a screening tool in groundwater protection and management. In this study, a series of vulnerability maps were made for the Greater Oliver area, in south central Okanagan, British Columbia, Canada, to test the sensitivity of the methodology to changes in input data type, interpretation, and mapping approaches. The study also illustrates how DRASTIC can be modified for use in areas of limited geological variability, where it may be important for smaller-scale changes in vulnerability to be recognized. Maps were produced using the original DRASTIC rating tables, a set of expanded tables using the original properties but modified ranges to accommodate the variability of data in the valley bottom region, and alternate tables, with modified properties and ranges. Differences in vulnerability rating for the maps using selected combinations and data interpretations are compared to the map using original DRASTIC rating tables using visual and statistical methods. One map was generated using expert hydrological knowledge. The modified tables allowed a greater amount of variability to be expressed in the valley bottom area compared to using the original tables and methods, and could provide a reasonable approach for assessing local scale variability for source water protection planning.     

基于3D WebGIS月球地质空间数据管理系统

随着空间信息技术、地学信息技术和GIS等技术的飞速发展,利用QT结合OpenGEL技术建立基于3D WebGIS月球地质空间数据管理系统。该系统包含二维成果管理系统、发布系统与三维月球研究3个子系统,实现改善月球资料信息使用效率、信息化程度与多源空间数据共享。将中国探月计划所获取的月球地形地貌、岩层、土壤、资源、环境及各种相关数据资料与研究成果,以及国外包含数据、文献、报告等月球探测的研究最新成果集成在一起,建立了中国第一个月球地质空间数据管理系统。该信息系统既包含管理和服务功能,又提供面向科研、决策的信息服务与科学的分类管理、快速检索和联机查询的功能。地质空间数据管理系统具备强大的数据综合分析能力、综合管理月球地质资料与集成数据资料成果的汇总能力,将为中国探月工程提供有力的支撑。     

US billion-dollar weather and climate disasters: data sources, trends, accuracy and biases

This paper focuses on the US Billion-dollar Weather/Climate Disaster report by the National Oceanic and Atmospheric Administration’s National Climatic Data Center. The current methodology for the production of this loss dataset is described, highlighting its strengths and limitations including sources of uncertainty and bias. The Insurance Services Office/Property Claims Service, the US Federal Emergency Management Agency’s National Flood Insurance Program and the US Department of Agriculture’s crop insurance program are key sources of quantified disaster loss data, among others. The methodology uses a factor approach to convert from insured losses to total direct losses, one potential limitation. An increasing trend in annual aggregate losses is shown to be primarily attributable to a statistically significant increasing trend of about 5 % per year in the frequency of billion-dollar disasters. So the question arises of how such trend estimates are affected by uncertainties and biases in the billion-dollar disaster data. The net effect of all biases appears to be an underestimation of average loss. In particular, it is shown that the factor approach can result in a considerable underestimation of average loss of roughly 10–15 %. Because this bias is systematic, any trends in losses from tropical cyclones appear to be robust to variations in insurance participation rates. Any attribution of the marked increasing trends in crop losses is complicated by a major expansion of the federally subsidized crop insurance program, as a consequence encompassing more marginal land. Recommendations concerning how the current methodology can be improved to increase the quality of the billion-dollar disaster dataset include refining the factor approach to more realistically take into account spatial and temporal variations in insurance participation rates.     

大数据环境下数字填图数据集成服务技术

应用数字填图技术形成了大量地质填图图幅数据,这些数据空间结构化和非结构化特征并存,如何在网络环境下提供高效的数据服务是急需解决的一个难题。大数据技术的发展为数字填图、数据集成服务提供了一种新的途径。通过对数字填图数据特征的分析,在研究地质调查信息网格大数据处理框架的基础上,提出了结构化和非结构化数据相结合的有序化组织管理、发布与服务方法,并对关键技术进行了研究与试验,取得了良好的效果。     

Hazard mapping based on macroseismic data considering the influence of geological conditions

The object of this study is to consider directly the influence of regional geological conditions on the assessment of seismic hazard. It is assumed that macroseismic data at individual locations contain, in an average way, the influence of geological conditions.A Data Base referring to 199 historical (5) and instrumental (194, in the 1947–1993 period) events with macroseismic information in 1195 locations of Portugal was built. For any given seismic event, whenever macroseismic information was available at a location (town, village, etc.), an EMS-92 intensity value was estimated. To each one of those locations a geological unit, representing the most common type of soil, was assigned, based on the Geological Portuguese Map at a scale 1:500 000; the geological units were grouped into three categories: soft, intermediate and hard soils.The Data Base was used to determine the attenuation laws in terms of macroseismic intensity for the three different geological site conditions, using multiple linear regression analysis. The reasonability of the laws was tested by (i) checking residual distributions and (ii) comparing the map of isoseismals of important earthquakes with the isoseismals generated by the attenuation curves derived for each one of the three different soil classes, taking into consideration the soil class of each site. The main results of attenuation modeling are: high dispersion on macroseismic intensity data; all the models predict intensity values, for short hypocentral distances, lower than the ones observed; and for some important analyzed earthquakes and for the observed range of distances, the models confirm the expectancy that macroseismic intensity increases from hard to soft soil.The approach to obtain the hazard assessment at each location consisted in the use of the attenuation law specifically derived for the class of soil of that particular location. This method, which considers the influence of the regional geology, was illustrated with the mapping of hazard for the country for several return periods. Comparison with previous maps not taking into consideration the regional geological conditions emphasizes the importance of this new parameter. It can be concluded that (i) soil segmentation is clearly the cause for hazard increase in the region to the north of Lisbon, especially at sites with soft and intermediate soils as the ones in lower Tagus valley; the maximum increase on hazard is, in any case, less than one degree; (ii) when geological conditions are disregarded in the attenuation regression analysis, hazard pattern is similar to the one obtained for the case of hard soil everywhere.     

大数据环境下数字填图数据集成服务技术

应用数字填图技术形成了大量地质填图图幅数据,这些数据空间结构化和非结构化特征并存,如何在网络环境下提供高效的数据服务是急需解决的一个难题。大数据技术的发展为数字填图、数据集成服务提供了一种新的途径。通过对数字填图数据特征的分析,在研究地质调查信息网格大数据处理框架的基础上,提出了结构化和非结构化数据相结合的有序化组织管理、发布与服务方法,并对关键技术进行了研究与试验,取得了良好的效果。     

基于GIS的空间数据和空间数据库浅谈

在数字城市、数字省区等数字工程建设和各个部门信息化建设迅速开展的时候，大量甚至海量空间数据的存储和管理成为地理信息系统建设工作者们面临的重要问题，研究空间数据和空间数据库变得非常迫切。简要介绍了空间数据的概念、特征和空间数据结构模型，并对空间数据库的设计做了简单阐述。