地理信息系統(tǒng)gisppt課件(編輯修改稿)
2025-06-08 13:55 本頁面
【文章內(nèi)容簡介】 position and shape of the building is captured as a series of four pairs of numerical coordinates. Geographic Information System GIS Raster data In raster data the entire area of the map is subdivided into a grid of tiny cells. A value is stored in each of these cells to represent the nature of whatever is present at the corresponding location on the ground. Raster data can be thought of as a matrix of values. Geographic Information System GIS ?The values recorded in the cells are either white, blue or red. ?To reproduce the image the puter reads each of these cell values one by one and applies them to the pixels on the screen. Geographical Information System GIS Vector v Raster Vector: Relatively low data volume Faster display Can also store attributes Less pleasing to the eye Raster: Relatively high data volume Slower display Has no attribute information More pleasing to the eye Geographical Information System GIS Geographical Information System GIS ?In this example the raster data looks nicer but, as you zoom in, the pixel structure bees obvious. Eventually the image looks like a piece of modern art rather than a detail of a map! ?The definition of the features is dependent upon the size of the individual grid cells – the resolution. ?The vector data is more like a graph with a line drawn between points, the width staying the same however close you zoom. Geographical Information System GIS Geographical Information System GIS Geographical Information System GIS Geographical Information System GIS Geographical 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 Geographical Information System GIS Any successful example of GIS is based on two fundamental ponents: ? the map data。 and ? the puter software to perform calculations and analysis. Geographical Information System GIS There are many different anisations producing data for use in GIS。 There is also a large industry in GIS software with hundreds of panies producing thousands of products. Software: ? GIS Software – ArcGIS(ArcInfo, ArcView), MapInfo, etc. ? Database – MS Access, Oracle, Sybase, dBASE ? Spatial Data Analysis – SPLUS, SPSS ? Inter Mapping System ArcIMS ? System Analysis Tool – CASE, Visio, ModelBuilder Geographical Information System GIS Geographical Information System GIS People: ? IT Administrators ? GIS Analysts ? GIS Technicians ? Application Experts – Spatial Data Analyst ? End Users Geographical Information System GIS Hardware: ? Computer (PC or UNIX) ? Digitizer/Scanner ? Plotter / Printer ? Network System / GPS Units ? CDROM or Data Storage Devices Geographical Information System GIS Geographical 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 Geographical Information System GIS Scale basics A description of scale can lose its meaning – the scale of the image on screen can depend on the monitor size. The image above may appear 13 mm long on some screens but not others. Geographical Information System GIS Scale of capture ?All GIS packages enable you to zoom in and out on the map data as much as you like. ?However, all topographic data has a scale of capture
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