The Geo-modifier maps points into geographic space, using dem earth as a reference. It doe not simply drop onto polygons, and as you can see from this video, it maps beyond the surface of the DEM Earth object. With this modifier, you can modify any point based object to take the form of the DEM Earth landscape. you can even turn the parent landscape of, and the points will behave as they should.
DEM Earth Geo Modifier workout from Tools4D on Vimeo.