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Chapter 4

Chapter 4. Data Input 数据输入. 浙江水利水电专科学校 PowerPoint by 僧德文. CHAPTER 4 DATA INPUT 第 4 章 数据输入. 4.1 Existing GIS Data 现有的地理信息系统数据 4.2 Metadata 元数据 4.3 Conversion of Existing Data 现有数据的转换 4.4 Creating New Data 创建新数据. Chapter 4 Data Input 第 4 章 数据输入.

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Chapter 4

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  1. Chapter 4 Data Input 数据输入 浙江水利水电专科学校 PowerPoint by 僧德文

  2. CHAPTER 4 DATA INPUT第4章 数据输入 • 4.1 Existing GIS Data 现有的地理信息系统数据 • 4.2 Metadata 元数据 • 4.3 Conversion of Existing Data 现有数据的转换 • 4.4 Creating New Data 创建新数据

  3. Chapter 4 Data Input第4章 数据输入 • Most expensive (and time consuming) phase of a GIS project 一个GIS项目中最昂贵（且最耗时）的阶段 • Process of conversion from paper maps (analog) to digital 纸质地图转化为数字地图的过程 • Existing data becoming more common, thus reducing the need to create original data 现有数据越来越公共化，减少了创建新数据的需求

  4. Data Input数据输入 • Topic still important 数据输入仍很重要 • 1. Public data intended for all users 公共数据倾向于为所有用户使用 • Metadata 元数据 • Data conversion 数据转换 • 2. Proliferation of data suggests that new data constantly being created 数据的激增表明新数据不断被创建 • Need may exist to create own data 仍然存在创建自己所需数据的必要

  5. 4.1 Existing GIS Data现有的地理信息系统数据 • Government agencies at all levels 各级政府机构 • Private sources 私人数据 • Format compatibility issues 数据格式兼容性问题 • Framework data 框架数据

  6. 4.1 Existing GIS Data现有的地理信息系统数据 • Public data generally free or for cost of processing 公共数据通常是免费的或仅收取处理的成本 Clearinghouses 数据交换中心

  7. 4.1.1 Federal Geographic Data Committee (FGDC)联邦地理数据委员会 • Interagency committee 中间机构委员会 • Develop metadata standards 发展元数据标准 • Coordinate NSDI (National Spatial Data Infrastructure) 协同国家空间数据基础设施

  8. 4.1.2 Geospatial One-Stop地理空间访问站点 • Geospatial data portal established by Federal Office of Management and Budget 地理空间数据入口是联邦管理预算事务所建立的 • Links to NSDI and state, regional, and local clearinghouses 链接国家空间数据基础设施和州、地区和地方数据交换中心

  9. 4.1.3 U.S. Geological Survey美国地质调查局 • National Map Program 全国制图计划 • Digital Line Graphs (DLGs) 数字线状图 • National Land Cover Data (NLCD) 全国土地覆被数据 • Digital elevation models (DEMs) 数字高程模型 • Several other digital products available through USGS 通过USGS可以得到其他的数字产品

  10. 4.1.4 U.S. Census Bureau美国人口普查局 • TIGER/Line files 拓扑统一地理编码格式/线文件

  11. 4.1.5 Natural Resource Conservation Service (NRCS)自然资源保持局 • Branch of USDA 美国农业部的分支 • Soils data 土壤数据 • Also, several other federal agencies not listed in textbook (U.S. forest Service, BLM, etc.) 还有其他几个联邦机构课本上没有列出

  12. 4.1.6 Statewide Public Data州域公共数据 • Geospatial One-Stop provides link to every state data clearinghouse 地理空间访问站点 提供与每一个州数据交换中心的链接 • Example: Montana State Library

  13. 4.1.7 Regional Public Data区域公共数据 • Example: Greater Yellowstone Area Data Clearinghouse 大黄石地区数据交换中心

  14. 4.1.8 Metropolitan Public Data大都市公共数据 • Example: San Diego Association of Governments 圣地亚哥政府协会

  15. 4.1.9 County-Level Public Data县级公共数据 • Example: Clackamas County, Oregon

  16. 4.1.10 GIS Data from Private Companies 私人公司的GIS数据 • Commercial data 商业化数据 • Some is specialized for specific client types 一些是为专门用户提供的专用数据

  17. 4.2 Metadata元数据 • Data about data 描述数据的数据 • Information about the content of a geospatial data file 关于地理数据文件内容的信息 • Will data meet a specific need? 数据是否满足特定要求？ • How to transfer, process, and interpret geospatial data 怎样转换、处理、解释地理空间数据 • Contact for additional information 联系获取附件信息

  18. Identification 识别 Data quality 数据质量 Spatial data organization 空间数据组织 Spatial reference 空间参照系 Entity and attribute实体与属性 Distribution 分布 Metadata reference元数据参照系 FGDC StandardsAdopted by federal agencies被联邦机构采用的联邦地理数据委员会标准

  19. 4.3 Conversion of Existing Data现有数据的转换 • Public data in a variety of formats 公共数据表达格式各异 • Must be converted to format compatible with your software 必须转换为同你软件相兼容的格式

  20. 4.3.1 Direct Translation直接转换 • Uses a translator embedded in the software to convert from one format to another 用GIS软件中的译码器将（空间数据）从一种格式直接转换成另一种格式

  21. Figure 4.1 The MIF to Shapefile tool in ArcGIS converts a MapInfo file to a shapefile. ArcGIS内的MIF到Shapefile 转化工具将MapInfo文件转化为shapefile格式

  22. 4.3.2 Neutral Format中间转换 • Public or defacto format for data exchange 用于数据交换的公共的或实际的格式 • DLG example

  23. Spatial Data Transfer Standards (SDTS)空间数据转换标准 • Neutral format approved by FIPS 联邦信息处理标准核准的中间转换格式 • Many federal agencies have converted some of their data to SDTS format 许多联邦机构已将其部分数据转换为SDTS格式 • GIS vendors provide translators GIS销售商提供数据译码器

  24. Figure 4.2 To accommodate users of different GIS packages, a government agency can translate public data into a neutral format such as SDTS format. Using the translator in the GIS package, the user can convert the public data into the format used in the GIS. 为适应不同GIS软件包的用户，政府机构可把公共数据转换为中间格式 ，用户可用软件包中的数据译码器将其转换为适用的格式

  25. Vector Product Format (VPF)矢量数据产品格式 • Standard format, structure, and organization for large geographic databases based on georelational model 针对基于地理相关模型的大型地理数据库的一种标准格式、结构和组织

  26. 4.4 Creating New Data创建新数据 • Occasionally must create custom data when data not available through other sources 当所需数据不能从其他数据源得到时就要创建新的数据了

  27. 4.4.1 Remotely Sensed Data遥感数据 • Satellite images, image analysis 卫星影像，影像分析 • Resolution issues 分辨率问题 • DOQs and other aerial photography 数字正射影像和其他航空摄影

  28. Figure 4.3 A digital orthophoto (DOQ) can be used as the background for digitizing or updating of existing maps. DOQ可用于数字化背景图或更新现有地图

  29. 4.4.2 Field Data野外数据 • Surveying, GPS测量、GPS Figure 4.4 A bearing and a distance determine a course between two stations. 方位和距离决定了两站之间的路线

  30. Figure 4.5 Use four GPS satellites to determine the coordinates of a receiving station. xi, yi, and ziare coordinates relative to the center of mass of the Earth. Ri represents the distance (range) from a satellite to the receiving station. 用4颗GPS卫星来确定接收站的坐标，xi,、yi和zi是相对于地球质量中心的坐标 ，Ri表示从卫星到接收站的距离

  31. Figure 4.6 A portable GPS receiver. (Courtesy of Trimble.) 便携式GPS接收机

  32. Figure 4.7 Elevation readings from a GPS receiver are measured from the surface of the geoid rather than the spheroid. 从GPS接收机读取的高程数据是以大地水准面而不是椭球面为基准的

  33. 4.4.3 Text Files with x-, y- Coordinates带有x、y坐标的文本文件 • Entered as text into a spreadsheet 以文本格式输入表格

  34. 4.4.4 Digitizing Using a Digitizing Table用数字化仪作数字化 • Digitizing is process of converting from analog to digital format 数字化是将数据由模拟格式转化成数字格式的 过程 • Accuracy and precision issues 准确和精确度问题 • Snapping tolerances 节点捕捉容差值 • Control points 控制点 • Avoiding duplicate lines 避免线段重复输入

  35. Figure 4.8 A large digitizing table and a cursor with a 16-button keypad. (Courtesy of GTCO Calcomp, Inc.) 大幅面数字化仪，键区带有16个按钮的游标

  36. Figure 4.9 The end of a new line can be automatically snapped to an existing arc if the gap is smaller than the specified snapping tolerance. 如果一条新线的节点与已有弧段的间距小于特定节点捕捉容差值，该节点可自动连接到已有弧段。

  37. Figure 4.10 A point (node or vertex) can be automatically snapped to another point if the gap is smaller than the specified snapping tolerance. 如果一个节点与已有节点间距小于特定节点捕捉容差值，该节点可自动连接到已有节点 。

  38. 4.4.5 Scanning扫描 • Converts an analog map to a raster file and then back to a digital vector file将模拟地图转化为栅格文件再回到数字化矢量文件 Figure 4.11 Large format drum scanners. (Courtesy of GTCO Calcomp, Inc.) 大幅面滚筒式扫描仪

  39. Figure 4.12 A binary scanned file: the lines are soil lines, and the black areas are the background. 二值栅格文件：线条为土壤界线，黑色区域为背景。

  40. Figure 4.13 A raster line in a scanned file has a width of several pixels. 扫描文件的一条栅格线有几个像元宽 Figure 4.15 The width of a raster line doubles or triples when lines meet or intersect. 栅格线会合或交叉时，线宽为原来两三倍

  41. Figure 4.14 Semiautomatic tracing starts at a point (shown with an arrow) and traces all lines connected to the point. 半自动化跟踪始于一个点（箭头处），然后跟踪与该点相连的所有线

  42. 4.4.6 On-Screen Digitizing屏幕数字化 • Heads-up digitizing 屏幕数字化 • Efficient method for editing or updating existing data 编辑或更新现有数据的有效方法

  43. 4.4.7 Importance of Source Maps源地图的重要性 • Existing maps still a dominant source for creating new GIS data 现有地图仍是创建新GIS数据的主要来源 • Accuracy of digital map directly related to accuracy of source map 数字地图的准确性与源地图的准确性直接相关

  44. Accuracy of Source Maps源地图的准确性 • Compilation of source maps 源地图的编制 • Cartographic license 地图绘制的许可 • Unstable base of paper maps 纸质地图的不稳定基础 • Original drafting processes 最初绘图稿过程

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