【正文】 o input data, store it, manage it, process it, and output it in the form of meaningful information Geographic Information System: A puterbased information system that enables capture, storage, retrieval, sharing, manipulation, analysis, modeling, and presentation of geographically referenced data. Geographic Information System GIS What is GIS? Geographic Information System GIS ?“A puter system for collecting, checking, integrating and analyzing information related to the surface of the earth.” (Rhind,1988) ?In other words, GIS is both a database system with specific capabilities for spatially referenced data as well as a set of operations for working with the data. It may also be considered as a higher order map. Geographic Information System GIS What is GIS? ?Set of tools for collecting, storing, retrieving at will, transforming and displaying spatial data from the real world for a particular set of purposes (Burrough, 1986 ) ?a puter based system that provides four sets of capabilities to handle georeferenced data : data input data management (data storage and retrieval) manipulation and analysis data output. (Arnoff ,1989 ) Geographic Information System GIS What is GIS? Geographic Information System GIS What is GIS? ? a puter based system ? spatially referenced data ? input, manage, analysis, output, share Advantages of GIS ? GIS is good at… – handling spatial data – visualisation of spatial data – integrating spatial data – framework for: ? analysis and modelling ? decision support Geographic Information System GIS (dis)Advantages of GIS ? GIS is not so good at… – handling temporal data – visualisation of temporal data – integrating spatial and temporal data – framework for: ? analysis and modelling of time dependent data ? volumetric analysis ? uncertainty Geographic Information System GIS Geographic Information System GIS Introduction 1. What is GIS? 2. In the beginning.... there were maps 3. Raster and vector 4. GIS = software + data.... 5. The significance of scale 6. Basic functions of GIS Geographic Information System GIS Without map? The story of GIS begins in the world of maps. The natural environment is… extremely plex highly variable (space and time) plicated further by human action Geographic Information System GIS Map types Geographic Information System GIS A Topographic map shows the physical surface features, for example, roads, rivers, buildings. A Contour map shows lines which connect point locations at which a certain property has the same value, for example, height above sea level, isobars showing air pressure. A Choropleth map shows areas characterised by some general mon feature, for example, political maps, agricultural crop types. Map features all map features can be divided into one of four different categories: Geographic Information System GIS ? ? Point (for example, a cross symbol to represent a church). ? Line (for example, a yellow line to represent a road). ? Polygon shape or area (for example, a blue area to represent a lake). ? Text (for example, the name of a building). Map features Geographic Information System GIS How is map information translated into digital form and read by a puter? The GIS must be able to store information about: ? The geometry: the shape and location of the objects. ? The attributes: the descriptive information known about the objects, norma