Here are some basic instructions for converting/importing GIS building and terrain shapefile data into 3DS, Rhino, etc. This may not be the most elegant or efficient manner of conversion out there, but it does the job.
The process of converting GIS building and terrain data into a usable, 3D model, is a relatively simple (but not necessarily) straightforward task. The general idea is to use GIS data, including non-graphical data fields like ‘apex’ and ‘elevation,’ to create a 3D model that can later be edited with various 3D modeling software. For buildings, the method is to translate the building footprints (from the GIS shapefile), to their appropriate altitude (resting on the ground), then to extrude the footprints to their appropriate height (the apex of the building), and then export it all as a VRML geometry. For terrain, the method is to convert a contour map into a TIN (Triangulated Irregular Network), then to a Raster image, then back to a TIN, and then export it as VRML geometry.