Some georeferenced TIF files actually have XYZ data stored in them, like the the USGS NED DEM files in GeoTIFF format. In these cases, you can use the TIF file as a GRD file in Surfer, not a base map file. For example, you can make a 3D surface map or contour map directly from the TIF.

For example:

1. Click Home | New Map | Contour.
2. In the Open Grid dialog select All Files from the Files of Type drop down menu.
3. Select the TIF file and click Open. The contour map is created from the TIF file.

Updated October 25, 2018