Vertical Grid Shift Files

In order to perform vertical datum transforms (other than Local Ellipsoid Height transformations), you must first have the appropriate grid shift files. You can download these files directly from the Blue Marble Geographics website (www.bluemarblegeo.com). This is a self-installing file. By default, these files will be installed to the ".../Blue Marble Geo/Geographic Calculator/Data/Par_files/" directory.

If you choose to move the ".../Par_files/" directory, you must specify the path, in the Calculator, to the directory where the vertical grid shift (par) files reside.

To specify a new path to the ".../Par_files/" directory:

1. In the Geographic Calculator, go to OPTIONS --> PREFERENCES

2. Click on the Folders tab.

3. Under the Vertical Datum Grid Files, click the Browse button and navigate to where you placed the Par_files directory.

4. Click OK