Attached Link: http://www.renderosity.com/gallery.ez?ByArtist=Yes&Artist=nanotyrannus

While Gebe is correct that you CAN get DEM's into Vue using the handbook, what the handbook doesn't tell you is that most DEM files have an edge along the sides that has "null" data, which causes a large wall to come up around the DEM you are importing. What I have done (see the link below for some finished examples of my method) is to use a third party program called 3dem to seamlessly combine multipart DEM's and then crop it down to the area I need (the area must be constrained to a roughly 4 quad by 4 quad area as Vue 4 will either not import or give you a flat plain for anything larger.) You then export the cropped area to a USGS DEM format and then import into Vue. Also, you will have to scale the resulting DEM (no matter which method you use) vertically by quite a bit, I have yet to figure out the exact conversion. Hope this helps :)