How To: Add a custom projection to the GIS Portal Toolkit Map Viewer


The GIS Portal Toolkit (GPT) Map Viewer understands over 3000 projections, which are the projections that are registered by default with ArcIMS. However, situations occur where a needed projection is not part of this large list. Instructions provided describe how to add a custom projection and have it be recognized by the GPT Map Viewer.


  1. Create a text file called 'projcs' that defines the custom projection information according to the format discussed on ESRI Development Network (EDN)

    Assign any unused projection ID and name to your custom projection.



  2. Save the 'projcs' file in any folder used for storing custom projection engine information. For example: 'c:\program files\arcgis\arcims\customPE'
  3. Add a system environment variable called 'PEOBJEDITHOME'. Set the value to the folder path where the 'projcs' file is located. Go to Start > My Computer > right-click to Properties > select Advanced tab > Environment Variables > System Variables > New.
  4. The custom projection is now added. As an optional setting, the GPT Map Viewer can be configured to use this projection as its default projection, as well as add the projection to the list of favorites in the Map Viewer Properties dialog box.
  5. A client such as ArcMap does not know how to handle the new projection ID by default. So for setting up map services with this new projection as a default, the map server needs to spell out the entire projection string in the AXL file, rather than using the projection ID.


    <ENVELOPE minx="-400000" miny="45000" maxx="386000" maxy="400000" name="Initial_Extent" />
    <MAPUNITS units="meters" />
    <FEATURECOORDSYS string="<full string here>" />
    <FILTERCOORDSYS string="<full string here>" />

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