Here is an elementary question about the way to represent a
temperature field. I wish to obtain a 3d picture of a 3d field
((lat, long, alt)-> temp) on a 3d grid, with background a digital
elevation model ((lat,long)->elev), on a 2d grid. I have almost got
it. I still have two problems. First, sometimes the DEM appears as
a DEM in grey in a realistic way, sometimes it appears as a
polyhderic surface and I do'nt know how to control its appearence.
Second I wish to represent the temperature field by colouring the
points of a 3d grid; is there a simple way to colour just the points
with temperature in a given range ?