Also I think Form-Z has some tools for making terrains from contour lines, that is another possibility.

It's somewhat easier for a polygon mesh based approach to be used for terrains, since the irregularity of the contour lines does not tend to lend itself very well to the regular control point grid structure that a NURBS surface is based on.


You might also search for tools that deal with a "Triangulated Irregular Network", or TIN:
http://en.wikipedia.org/wiki/Triangulated_irregular_network

- Michael