GISFileFormats < Main

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---++File Formats for GIS Data

---+++++Vector Data:
   * Shapefile
      * Developed by ESRI for ArcView GIS
      * Specification is readily available; supported by other software
      * Does not support the storage of topological information
      * Can only store one feature class
      * It is a collection of 3 or more files:
         * Required files:
            * Main file: .shp
               * This is the primary file that stores feature geometry.
               * "It's a direct access, variable-record-length file in which each record describes a shape with a list of its vertices." (ESRI)
               * Stores integer and double-precision numbers (ESRI)
            * Index file: .shx
               * Stores the index of the feature geometry.
               * "Each record contains the offset of the corresponding main file record from the beginning of the main file." (ESRI)
            * Dbase table: .dbf
               * Stores the attribute data for features contained in .shp, with one record per feature.
               * There is a one-to-one relationship between geometry and attributes, which is based on record number. Attribute records in the dBASE file must be in the same order as records in the main file.
               * It is a mix of binary and ASCII data. Header contains binary data. The records are all in ASCII. (XBase)
         * Optional files:
            * Projection file: .prj
      * Sources: 
         * *ESRI Shapefile Technical Description:* http://www.esri.com/library/whitepapers/pdfs/shapefile.pdf
         * *XBase database Format:* http://www.clicketyclick.dk/databases/xbase/format/dbf.html#DBF_STRUCT
         * *GIS File Formats:* http://www.giscentrum.lu.se/english/whatisgisFileFormat.htm
 
   * Coverage
      * Developed by ESRI


-- Main.AprilWebster - 12 Mar 2007
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Topic revision: r3 - 2007-03-26 - AprilWebster