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GEOCOORD

GEOCOORD

Name


      GEOCOORD

Purpose



      The purpose of this function is to translate a GEOTIFF structure
      (as returned by QUERY_TIFF or READ_TIFF) into a map coordinate
      object (MAPCOORD) that can be used to georeference images with a
      map data coordinate system. Both the Coyote and Catalyst Libraries
      are required to be on your IDL PATH.

Author



        FANNING SOFTWARE CONSULTING
        1645 Sheely Drive
        Fort Collins
        CO 80526 USA
        Phone: 970-221-0438
        E-mail: davidf@dfanning.com

Category



      Image display and map projection.

Calling Sequence



      mapCoord = GeoCoord( geoTiffFilename )
       
    or
   
      mapCoord = GeoCoord( image, geotiff )
     

Arguments


 
    geoTiffFilename: The name of a GeoTIFF file from which can be obtained
                        the geoTIFF structure of geoTags and the dimensions of the image.
                       
    or
   
    image: A GeoTIFF image.
   
    geotiff: A GeoTIFF structure of geoTags. Normally obtained by calling
                          QUERY_TIFF or READ_TIFF.
                         

Keywords


 
    GRID_COLOR: The name of a color the map grid should be displayed with. The default
                          is "indian red". Color names are those supported by cgColor.
                         
    MAP_GRID: If a MapCoord object is made successfully, then setting this keyword
                          will add a Map_Grid object to the MapCoord object.
    MAP_OUTLINE: If a MapCoord object is made successfully, then setting this keyword
                          will add a Map_Outline object to the MapCoord object.
                       
    OUTLINE_COLOR: The name of a color the map outline should be displayed with. The default
                          is "indian red". Color names are those supported by cgColor.
                       
    SILENT: IDL cannot map every GeoTiff image to a supported map projection or datum.
                          Normally, if the GeoTIFF image is unsupported, an error message is issued.
                          Setting this keyword will suppress such error messages. If you do this, you
                          MUST check the SUCCESS keyword to see if the program ran successfully. (Of
                          course, it is a good idea to check it in any case!)
                         
    SUCCESS: An output variable that will contain a 1 if the map coordinate object was
                          created successfully. Or to a 0 if it was not created successfully.
                         

Return Value


 
    mapCoord A MAPCOORD object that can be used as the data coordinate object for
                          a TIFF image. Creation of this object requires that the Catalyst Library
                          be on your IDL path.
                         

Notes


 
    It is not possible to have a one-to-one mapping between every GeoTIFF file and a map projection
    in IDL, since IDL has a limited number of map projections and datums available. And, even at that,
    I have not implemented all of IDL's map projections or datums, only those that I thought were most
    likely to be encountered in my own work. If you run into a GeoTIFF file that does not work in this
    code (either because of an error in the code or because it is not supported), please contact me.
    I am interested in supporting as many GeoTIFF files as possible and I will take pains to do so if
    I know they are needed.
   

Restrictions


 
    Programs from both the Coyote and Catalyst Libraries are required to run this code.
   
      http://www.dfanning.com/catalyst/howtoinstall.html

Modification History



      Written by: David W. Fanning, 30 August 2009.
      Removed the requirement that the GTRasterTypeGeoKey has to be "PixelIsArea". It
          can now also be "PixelIsPoint". 10 February 2010. DWF.
      Added ability to add MAP_OUTLINE and MAP_GRID objects to the output MapCoord object.
          New keywords OUTLINE_COLOR, MAP_OUTLINE, GRID_COLOR, and MAP_GRID. 20 Feb 2010, DWF.
      Switch UTM datum from WGS84 to WALBECK to avoid UTM projection bug in all versions
            of IDL prior to IDL 8.2, when it is suppose to be fixed. For more information,
            see this article: http://www.idlcoyote.com/map_tips/utmwrong.php. 31 Oct 2011. DWF.



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