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GIS A geographic information system. A GIS is most often associated with a map. A GIS is most often associated with a map. The map is a display of a data.

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Presentation on theme: "GIS A geographic information system. A GIS is most often associated with a map. A GIS is most often associated with a map. The map is a display of a data."— Presentation transcript:

1 GIS A geographic information system

2 A GIS is most often associated with a map. A GIS is most often associated with a map. The map is a display of a data base in map form The map is a display of a data base in map form The data base is A relational database that groups data using common attributes found in the data set The data base is A relational database that groups data using common attributes found in the data set

3 Example presented the data to the user as relations ( a collection of tables with each table consisting of a set of rows and columns, with each flat table have a common row.) presented the data to the user as relations ( a collection of tables with each table consisting of a set of rows and columns, with each flat table have a common row.) provided relational operators to manipulate the data in tabular form provided relational operators to manipulate the data in tabular form

4 relational database have a location or area associated with the value. relational database have a location or area associated with the value. The area can be raster position which is a square or a given area on a map The area can be raster position which is a square or a given area on a map The area can be a shape area defined by a polygon. The area can be a shape area defined by a polygon.

5 Grass a raster data base (free) http://grass.itc.it/ Grass a raster data base (free) http://grass.itc.it/ http://grass.itc.it/

6 Raster

7 ARC View (polygon)

8 Awhere is a limited version of GIS learning curve only 4 hr. Awhere is a limited version of GIS learning curve only 4 hr. Associated with each data base file is a shape file that contains the shape of the polygon for each element in the data base.

9 Shape files and attribute files for new mexico are available at Shape files and attribute files for new mexico are available at http://rgis.unm.edu/clearinghouse.cfm http://rgis.unm.edu/clearinghouse.cfm http://rgis.unm.edu/clearinghouse.cfm


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