Datum Shift Issues for North American Users
Concept Procedure
 
 
 

To use version 2 of the Canadian National Transformation

  1. Obtain a copy of the data file.

    Contact Information Services, Geodetic Survey Division, Geomatics Canada

    615 Booth Street

    Ottawa, Ontario, K1A 0E9

    (613) 995-4410

    http://www.geod.nrcan.gc.ca

  2. Once you have the file, copy it into the Autodesk shared coordinate system folder, by default C:\Documents and Settings\All Users\Application Data\Autodesk\Geospatial Coordinate Systems\Canada, and give it the name Ntv2_0.gsb.
  3. Using a text editor such as Notepad, open Nad27ToNad83.gdc (located by default in the C:\Documents and Settings\All Users\Application Data\Autodesk\Geospatial Coordinate Systems folder).
  4. Delete the initial pound sign (#) from the line that begins: #.\Canada\Ntv2_0.gsb.

To use version 1 of the Canadian National Transformation

  1. Obtain a copy of the data file.
  2. Copy it into the C:\Documents and Settings\All Users\Application Data\Autodesk\Geospatial Coordinate Systems\Canada folder, and give it the name grid11.dac.
  3. Open Nad27ToNad83.gdc.
  4. Delete the initial pound sign (#) from the line that begins: #.\Canada\grid11.dac.

For more information on editing GDC files, see Grid Data Catalog (GDC) Files.