Volunteered Geographic Information: A Bicycling Enthusiast Perspective

Mapping technologies have made considerable strides in recent decades. Global positioning systems (GPS), remote sensing satellites, Web-based mapping services, and geographic information systems (GIS) have facilitated the collection, distribution, analysis, and ultimately interaction with geospatial information. In particular, portable GPS have altered how individuals participate in mapping. Individuals can use GPS to collect tracings of their personal interactions with the environment. These interactions can then be uploaded to one of many available Web-based mapping services. Once uploaded, the geospatial data can be mapped and shared among the broader community of users. Such volunteered geographic information (VGI) exemplifies the conceptualization of an individual collecting, mapping, and sharing personal geographic information. This paper focuses on challenges surrounding VGI. To help place these challenges in a broader context, specialized Web services and GPS technologies developed for the bicycling community will serve as examples of the current status and future prospects of VGI.     

纸质地图与地理信息一体化生产技术研究

纸质地图制作和地理信息生产构成数字地图制图中两大相对独立的研究领域,在分析两者异同的基础上,设计了纸质地图与地理信息一体化生产流程,阐述了实现一体化生产必须解决一体化数据结构设计、多源数据综合利用、地图符号化机制建立、基于地理属性管理的地图编辑、地图数据质量检查、一体化地图输出等关键技术。纸质地图与地理信息一体化生产标志着数字地图制图发展进入了新阶段。     

基于VB + MapObjects的土地利用动态变化更新与实现

在土地利用动态监测中,地理信息系统是实现空间数据动态更新和分析的主要技术手段。本文分析了土地利用动态变化更新模式、土地利用图中图斑的特点以及图斑对象的更新模型,结合土地利用动态变化更新中的GIS空间分析方法,给出了土地利用动态变更中的图斑模型,采用VB+MapObjects进行了组件式GIS二次开发实现。经过实际数据的检验,证明了程序具有很好的稳定性、可靠性和较高的效率。     

Choosing Geographic Units for Choropleth Rate Maps,with an Emphasis on Public Health Applications

Choropleth maps are the most widely used map type for mapping rates, such as those involving disease, crime, and socioeconomic indicators. The essential step of choosing a geographic unit to map is often made in an ad hoc manner. Among the desirable characteristics of choropleth mapping units are high degree of resolution, homogeneity of population size, homogeneity of land area, observation of minimum population thresholds and land area thresholds, temporal stability and currency, compactness of shape, audience familiarity, data availability, and the functional relevance of the unit to the phenomena mapped. Because of the uneven distribution of human populations, no single geographic unit can meet all of these characteristics in practice, and a well designed choropleth map necessarily involves some compromise. We present guidelines for choosing geographic units that take into account the above criteria, considering 12 geographic units ranging from census blocks to states. Even allowing for differences in scale and purpose, some units confer clear advantages over others.     

Synergetic use of remote sensing and geophysical data for exploration of porphyry copper deposits, using GIS

Darrehzar porphyry copper deposit is situated in the Urumieh-Dokhtar magmatic assemblage of central Iran. In this paper, the integration of multiple geodata sets has been carried out using geographic information system for mapping lithology or hydrothermally altered rocks and also in selecting the best discriminating data elements for exploration of porphyry copper deposits located in areas with similar geological setting and climatic conditions. Principal component analysis is found useful for reducing large data sets into a few principal components. The integration of various geophysical data with SPOT image data through GIS has shown that the hydrothermal alteration and lithology can be mapped with more efficiency.     

基于多种相似度特征的道路实体融合方法

随着城市建设步伐的加快和基础地理信息应用领域的扩展,国家经济建设和人民群众生活对基础地理信息的需求越来越大,对基础地理信息的现势性和更新频率也提出了更高的要求。因此,对不同精度、不同来源的地理信息数据融合技术进行研究具有十分重要的意义。道路实体是重要的基础地理信息,尤其是铁路、高速、国省道、城市主干道。本文重点围绕道路实体研究数据间的差异性,建立了自动匹配评价指标;并基于FME平台搭建同名匹配、变化检测和增量更新模型,实现了道路实体自动更新和融合,缩短了道路实体更新周期。“十三五”第2轮基础测绘更新项目利用该技术完成了重要道路实体的融合,证明了该技术的可行性和准确性,为新型基础测绘体系的建设提供了技术支撑。     

Landscape drainage modelling to enhance Landsat classification accuracies

Studies integrating digital elevation models (DEMs) with multispectral digital satellite data have typically concentrated on geographic areas characterized by moderate to high topographic relief. Variables such as elevation, slope gradient and aspect contribute most significantly to the zonation of vegetation in these environments. In areas where relief is low, vegetation zonation is based not on individual form elements but rather on physical processes. The purpose of this research was to investigate the potential of integrating multispectral and ancillary process data in such a low relief environment. For this a study area was chosen in the Boreal forest of west central Alberta where the zonation of vegetation is based, to a large extent, on landscape drainage. An initial classification of forest cover based on Landsat multispectral data yielded overall classification accuracies of 58%. A DEM was developed from a digitized 1:50,000 topographic map sheet. The differential geometry of the DEM was mapped as a series of coverages: slope, aspect, and directional curvatures (down ‐ and across slope). Two additional coverages, relief and flow paths, were also developed and mapped. A data set was extracted from the DEM through which landscape drainage could be evaluated. A univariate analysis of drainage using the form variables resulted in a 45% to 47% explanation of the observed variation. Multivariate analysis combining slope gradient, across and down slope curvatures, relief, and flow paths increased the explanation to 68%. The MSS data were reinterpreted integrating the DEM ‐ based landscape drainage model. The resulting classification accuracy was increased to 73%.     

Influence of clock jump on the velocity and acceleration estimation with a single GPS receiver based on carrier-phase-derived Doppler

Since the Selective Availability was turned off, the velocity and acceleration can be determined accurately with a single GPS receiver using raw Doppler measurements. The carrier-phase-derived Doppler measurements are normally used to determine velocity and acceleration when there is no direct output of the raw Doppler observations in GPS receivers. Due to GPS receiver clock drifts, however, a GPS receiver clock jump occurs when the GPS receiver clock resets itself (typically with 1 ms increment/decrement) to synchronize with the GPS time. The clock jump affects the corresponding relationship between measurements and their time tags, which results in non-equidistant measurement sampling in time or incorrect time tags. This in turn affects velocity and acceleration determined for a GPS receiver by the conventional method which needs equidistant carrier phases to construct the derived Doppler measurements. To overcome this problem, an improved method that takes into account, GPS receiver clock jumps are devised to generate non-equidistant-derived Doppler observations based on non-equidistant carrier phases. Test results for static and kinematic receivers, which are obtained by using the conventional method without reconstructing the equidistant continuous carrier phases, show that receiver velocity and acceleration suffered significantly from clock jumps. An airborne kinematic experiment shows that the greatest impact on velocity and acceleration reaches up to 0.2 m/s, 0.1 m/s² for the horizontal component and 0.5 m/s, 0.25 m/s² for the vertical component. Therefore, it can be demonstrated that velocity and acceleration measurements by using a standalone GPS receiver can be immune to the influence of GPS receiver clock jumps with the proposed method.     

地学分析在遥感专题制图中的应用

为了提高数字图像制图的质量和精度, 许多研究人员部在从不同途径探索各种有效方法。本文从地学角度出发, 以地学知识和理论为基础, 结合遥感专题制图, 对成图信息源和数字图像识别的区域参数, 作了综合分析研究。本文重点讨论数字图像冬小麦的识别制图, 用地学、生物学知识和理论, 分析冬小麦等农作物的物候规律, 研究其分类识别的最佳时相图像; 另外, 结合盐碱土等地物的模式识别制图进行了区域参数的分析、确定和量化研究。     

WebGL在线动态地图服务框架设计

针对在线动态地图的交互性强、制图过程灵活、数据复杂多样、受众面广等特点及优势,本文基于WebGL技术设计了一种在线动态地图服务架构。该架构通过设计面向海量矢量数据的在线地图数据模型,定义在线地图切片的存储结构,并充分利用计算机硬件加速能力,实现了海量矢量切片数据的快速可视化和动态更新。为检验方法的可行性,利用该框架研发了某县的"多规合一"地理信息服务平台,结果表明,该框架提升了在线动态地图平台的实用性和操作性,为在线动态地图服务提供了可靠的理论和技术支撑。     

An Evaluation of Internet Versus Paper‐based Methods for Public Participation Geographic Information Systems (PPGIS)

Public participation geographic information systems (PPGIS) are an increasingly important tool for collecting spatial information about the social attributes of place. The availability of Internet‐based options for implementing PPGIS presents new opportunities for increased efficiency and new modes of access. Here we used a mixed‐mode approach to evaluate paper versus Internet mapping methods for the same PPGIS survey in Wyoming. We compared participant characteristics, mapping participation, and the spatial distribution of mapped attributes between participants who responded to the paper versus Internet option. The response rate for those who completed the paper version of the survey was nearly 2.5 times the response rate of the Internet version. Paper participants also mapped significantly more places than did Internet participants (43 vs. 18). Internet participants tended to be younger, more likely to have a college degree, and had lived in the region for less time than paper participants. For all but one attribute there was no difference in the spatial distribution of places mapped between Internet and paper methods. Using a paper‐based PPGIS survey resulted in a higher response rate, reduced participant bias, and greater mapping participation. However, survey mode did not influence the spatial distribution of the PPGIS data.     

省级地理信息动态更新技术体系研究

目前,测绘地理信息生产方式还是以传统的大规模、周期性、全要素生产为主,缺少覆盖更新数据采集、处理入库、提取分发、配图切片、发布全过程的数据标准、生产协调机制、工艺流程和支撑软件系统。本文从重要地理信息要素标准、地理信息变化发现、更新生产调度、外业要素采集、数据库更新与发布等地理信息更新全流程进行研究,提出了1∶1万基础地理信息数据及天地图数据动态更新工艺流程和生产组织模式,形成省级地理信息动态更新技术体系。     

BDS与GIS融合数据采集技术应用研究

针对地理信息综合数据采集与应用需求,基于北斗导航系统和开源MapWinGIS技术,研制了基于北斗导航系统的数据采集应用平台,解决了多源技术融合数据采集、坐标系自适应转换与快速匹配等关键技术问题。经过不同方案应用测试,结果表明,平台定位与底图匹配精度高,能够满足一般性的综合地理信息数据采集与底图调绘需求,可广泛应用于地理国情普查与监测、野外数码调绘及其他行业外业数据采集应用。     

基于盘锦地理国情普查成果滩涂监测数据的提取研究

根据测绘地理信息行业"十三五"规划,如何利用国情普查数据进行地理国情监测监测,成为未来几年测绘技术的一个重要课题。本文的实施以地理国情普查数据利用高分辨率航空影像确定和采集滩涂地表空间数据为范围,对为滩涂变化监测提供基础数据源进行了研究。     

Building population mapping with aerial imagery and GIS data

Geospatial distribution of population at a scale of individual buildings is needed for analysis of people's interaction with their local socio-economic and physical environments. High resolution aerial images are capable of capturing urban complexities and considered as a potential source for mapping urban features at this fine scale. This paper studies population mapping for individual buildings by using aerial imagery and other geographic data. Building footprints and heights are first determined from aerial images, digital terrain and surface models. City zoning maps allow the classification of the buildings as residential and non-residential. The use of additional ancillary geographic data further filters residential utility buildings out of the residential area and identifies houses and apartments. In the final step, census block population, which is publicly available from the U.S. Census, is disaggregated and mapped to individual residential buildings. This paper proposes a modified building population mapping model that takes into account the effects of different types of residential buildings. Detailed steps are described that lead to the identification of residential buildings from imagery and other GIS data layers. Estimated building populations are evaluated per census block with reference to the known census records. This paper presents and evaluates the results of building population mapping in areas of West Lafayette, Lafayette, and Wea Township, all in the state of Indiana, USA.     

VB环境下交互式GMT地学绘图软件的设计及实现

本文设计基于VB环境下的交互式GMT绘图软件。详细阐述VB环境下交互式GMT绘图软件总体结构,介绍GMT概述、站点分布图绘制、速度场图绘制、梯度色阶热力图绘制、时间序列图绘制、等高线图绘制和地震频率图绘制等七大模块功能,并对软件实现中相关技术问题给出处理办法。软件运行结果表明:该软件功能强、可靠性高、兼容性强,为地球科学领域各种类型的数据分析和可视化表达提供有力的工具。     

Monitoring the source of trans-national dust storms in north east Asia

Abstract

The vast expanse of the Gobi desert across the Mongolian plateau experiences frequent dust storms. In this isolated region remote sensing techniques can provide an effective measurement of dust storms. Brightness temperature channels 4, 5 of AVHRR/NOAA satellite data, emissive bands of MODIS/TERRA satellite data and meteorological station measurement data were used and tested for dust and sandstorm mapping in the desert area of Mongolia and northern China. The differences between thermal bands in combination with geographic information system (GIS) layers were used for mapping in this study. The results show that dust and sand storm maps can be achieved from emissive bands for monitoring of dust and sandstorms. Most active dust storm sources can occur in truly remote areas where there is little or no human activity, although many sources are associated with areas where human impacts are well documented. Thus, on a regional scale dust mobilisation appears to be dominated by natural sources.     

Differentiation for High-Precision GPS Velocity and Acceleration Determination

Accurate estimates of the velocity and acceleration of a platform are often needed in high dynamic positioning, airborne gravimetry, and geophysics. In turn, differentiation of GPS signals is a crucial process for obtaining these estimates. It is important in the measurement domain where, for example, the phase measurements are used along with their instantaneous derivative (Doppler) to estimate position and velocity. It is also important in postprocessing, where acceleration is usually estimated by differentiating estimates of position and velocity. Various methods of differentiating a signal can have very different effects on the resulting derivative, and their suitability varies from situation to situation. These comments set the stage for the investigations in this article. The objective is twofold: (1) to carry out a comprehensive study of possible differentiation methods, characterizing each in the frequency domain; and (2) to use real data to demonstrate each of these methods in both of the measurement and position domains, in conditions of variable, high, or unknown dynamics. Examples are given using real GPS data in both the measurement domain and in the position and velocity domain. The appropriate differentiator is used in several cases of varying dynamics to derive a Doppler signal from carrier phase measurements (rather than using the raw Doppler generated by the receiver). In the statistic case, it is seen that the accuracy of velocity estimates can be improved from 4.0 mm/s to 0.7 mm/s by using the correct filter. In conditions of medium dynamics experienced in an airborne gravity survey, it is demonstrated that accelerations as the 2–4 mGal level (1 mGal = 0.00001 m/s²) can be obtained at the required filtering periods. Finally, a precision motion table is used to show that when using the correct filter, velocity estimates under high dynamics can be improved by an order of magnitude to 27.0 mm/s. ? 1999 John Wiley & Sons, Inc.     

Mapping of wastelands of Kolar district using false colour composites of thematic mapper (TM) data

This study deals with the technique of remote sensing for identifying and deliniating wastelands in Kolar district of Karnataka. False colour composites of thematic mapper (TM) data supplemented by aerial photographs and toposheets wrere utiliesd for mapping wastelands. A map showing the geographic distribution of the wastelands in the districts was prepared on 1∶250,000 scales by compiling the individual wasteland sheets of 1∶50,000 scale. The seven different catagories of wastelands identified and mapped cover about 11.7% of the area in the district. A procedure for mapping wastelands has been worked out based on the experience gained in Kolar district which is a three phase system comprising image intrepretation of false colour composite of TM data, aerial photo interpretation and limited ground truth verification in the selected doubtful areas. This procedure was found to be adequate enough for mapping wastelands accurately in the shortest possible time with least expense and as such are recommended for mapping wastelands in other districts of the country.     

无人直升机航空应急测绘系统设计与实现

无人直升机具有环境适应能力强、机动灵活、可定点悬停的优势,在应急测绘地理信息保障中具有广泛的应用前景。本文从无人机平台、任务传感器、数据处理软件的集成关系入手,提出了包含结构设计、电气设计、控制流设计的多载荷一体化的集成设计方案,以及涵盖航摄设计、视频数据处理、光学面阵影像处理的软件系统集成方案;采用该方案实现了Z-5无人直升机航空应急测绘系统,并在安徽明光进行了飞行试验。结果表明,该系统可以同时获取视频和光学影像,并进行实时处理,满足实时提供应急测绘地理信息保障的要求。