Path computation on a terrain

I am pursuing a long term hobby project to develop a simple visual tool where a user will be able to perform a minimal 3D visualization of the terrain -- view portions of the terrain from different viewing positions, zoom etc -- and then select a source and destination point using a mouse and then request for a shortest path to be first computed and then displayed on the terrain.

As a further background: I have a couple of example DEM data sets; one with an elevation/height sample for each 30 meter X 30 meter cell in a grid (the USGS data set) and one with a higher resolution data set. From a limited research survey I have arrived at the position that it may be best to first perform a terrain triangulation of the data set to get a TIN and perform path computation on the TIN using one of a few algorithms.

Any suggestions as to what kind of open source or free tools or libraries I can use to:

(1) Generate a TIN -- I was planning to use gdal_merge to merge the gif files corresponding to the tiles of interest and then run a triangulating code (either my own or an existing one such as r.refine, although I havent tried it)

(2) Loading the TIN into app开发者_Python百科ropriate tool -- I dont know what tool to use -- the tool shd be able to display the TIN regions from various viewing positions and allow selection/deselection of points and allow display of segments on the terrain. I came across vterrain but not sure if that is appropriate.

The intent is once the selected points are communicated to a backend, the latter will compute the path and send it back to display in the tool.