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nullIntroduction to Geographic Information Systems Third EditionIntroduction to Geographic Information Systems Third EditionKang-tsung Chang PowerPoint by Paul R. LarsonChapter 1Chapter 1IntroductionCHAPTER 1: INTRODUCTIONCHAPTER 1: INTRODUCTIONChapter Outline 1.1 What Is a GIS? 1.2 A Brief History of GIS 1.3 Geographically Referenced Data 1.4 GIS Operations 1.5 Organization of This Book 1.6 Concepts and Practice1.1 What Is a GIS?1.1 What Is a GIS?Computer system for capturing storing querying analyzing and displaying geographically referenced data.Geographically Referenced DataGeographically Referenced DataAlso called geospatial data Describe both locations and characteristics of spatial featuresAbility to process geographically referenced data distinguishes GIS from other information systems. Ability to process geographically referenced data distinguishes GIS from other information systems. 1.1.1 GIS Applications1.1.1 GIS ApplicationsU. S. Geological Survey U. S. Census Bureau U. S. Forest Service HUD States, counties, cities, businesses1.1.2 Components of a GIS1.1.2 Components of a GISComputer System (hardware) GIS software Brainwave Infrastructure1.2 A Brief History of GIS1.2 A Brief History of GISComputer mapping at University of Edinburgh, Harvard University (SYMAP), etc. Canada Land Inventory Ian charge's Design with Nature Census Bureau’s DIME systemHistory of GISHistory of GISGUI (graphical user interface) Affordable hardware Public digital dataSoftware ProducersSoftware ProducersESRI Intergraph GRASS IDRISI others1.3 Geographically Referenced Data1.3 Geographically Referenced Data1.3.1 Spatial Data 1.3.2 Attribute Data 1.3.3 Joining Spatial and Attribute Data1.3.1 Spatial Data1.3.1 Spatial DataDescribes location Coordinate system Map projectionCoordinate SystemsCoordinate SystemsFigure 1.1: An example of geographically referenced data. The street network is based on a plane coordinate system. The box on the right lists the x- and y-coordinates of the end points and other attributes of a street segmentProjectionsProjectionsProjecting from the spherical shape of the Earth to the planar shape of the map1.3.1 Spatial Data1.3.1 Spatial DataDiscrete features (points) Continuous features (areas) Sequential features (lines) - in between discrete and continuous1.3.1 Spatial Data1.3.1 Spatial DataFigure 1.2 The vector data model uses x-, y-coordinates to represent point features (a), and the raster data model uses cells in a grid to represent point features (b). 1.3.1 Spatial Data1.3.1 Spatial DataTopologyFigure 1.4 A classification of data formats used in ESRI software by topology and data model.1.3.1 Spatial Data1.3.1 Spatial DataComposite features built from simple features of points, lines, polygonsTringulated Irregular Network (TIN) ModelTringulated Irregular Network (TIN) ModelFigure 1.5 An example of the TIN model. Regions ModelRegions ModelFigure 1.6 An example of the regions model. Two regions, one for burned areas in 1919 and the other in 1929, overlap each other in some areas. Each region is also comprised of spatially disjoint parts.Dynamic Segmentation ModelDynamic Segmentation ModelFigure 1.7 An example of the dynamic segmentation model. Rest areas are plotted as point features on highway routes in Washington State. 1.3.2 Attribute Data1.3.2 Attribute DataCharacteristics of spatial features Non-spatial attributes of those features1.3.3.Joining Spatial and Attribute Data1.3.3.Joining Spatial and Attribute DataRelational database Georelational data model Object-based data model1.4 GIS Operations1.4 GIS Operations1.4.1 Spatial Data Input 1.4.2 Attribute Data Management 1.4.3 Data Display 1.4.4 Data Exploration 1.4.5 Data Analysis 1.4.6 GIS Models and Modeling See Figure 1.81.4.1 Spatial Data Input1.4.1 Spatial Data InputData acquisition most extensive phase of a GIS project Two operations Using existing data Create new data1.4.2 Attribute Data Management1.4.2 Attribute Data ManagementTables Rows - a specific feature Columns (fields) - characteristics of data Operations include input, search, retrieval, manipulation, output Key - in relational database, link between tables and spatial data1.4.3 Data Display1.4.3 Data DisplayMaps most important display medium Map design critical step to success of project1.4.4 Data Exploration1.4.4 Data ExplorationSearch for general trends in data Query1.4.5 Data Analysis1.4.5 Data AnalysisHeart and soul of GIS process Vector tools Buffer, overlay, distance and area measurement Raster tools Local, neighborhood, zonal, global operations Many morenullFigure 1.9 A vector-based overlay operation combines spatial data and attribute data from different layers to create the output.nullFigure 1.10 A raster data operation with multiple rasters can take advantage of the fixed cell locations.1.4.6 GIS Models and Modeling1.4.6 GIS Models and ModelingModel - a simplified representation of a phenomenon or system Many types Binary models Index models Regression models Process models1.5 Organization of This Book1.5 Organization of This BookGIS data and data models (chapters 2-5) Data input and management (chapters 6-9) Data display and exploration (chapters 10-11) Core data analysis (chapters 12-13) Surface analysis (chapters 14-16) Line analysis (chapters 17-18) Models and modeling (chapter 19)1.6 Concepts and Practice1.6 Concepts and PracticeTwo-part chapter structure Topics and concepts Applications