topographic displays
Hello from behind the learning curve,
I have a project I am trying to complete and have dug myself into a corner.
Basically I need to render a 3d Topography with some freeways and other
utilities displayed on it.
Thru vistapro, and autocad I managed to get the topo. The area is massive,
I had to piece it together from 6 DEM data files (each one is 10 megs ascii)
I have ended up with a topo mesh that is 48,000 faces (it covers a couple
hundred square miles)
Now my problem.
I need to lay objects onto this surface. Take a freeway for example.
The method I used that is causing me problems is:
In autocad I can project plan entities onto a mesh. This gives me a 3d polyline
that I can DXF in as a path in the Lofter and then run a simple quad down it as
a
shape. The problems I have are
1. due to the limitations of autocad the 'freeway' doesn't lay on the topo
nicely
it dives thru or rises above the surface. I have been cleaning up vertex by
vertex, but have rapidly become overwelmed.
2. If I decide the shape I used is to small to render nicely I need to re-Loft
it
and have to go thru the clean up again.
What I would like to do is export the plan view of the 'freeways' to a paint
program and then 'decal' them on to the surface.
Questions:
1. if I scale the plan view down to say '5"x5"' (remember they are currently
in
real world coordinates) will I be able to rescale the decal back up in 3DS
and position it accuratly?
I guess the question is how do you scale and position a decal accurtetly?
2. What size (resolution) do I need to make my decal? I need to be able to
see a freeway from '10 miles' away and when I zoom into it I don't want it
too out of scale. I know I will need to exaggerate somewhat but is there
a direct relationship between pixel width in a file and the scaled width of
a decal? Is it dependent on the size of the texture file.
I guess the optimum would be to create a texture file at the same scale
as the topo mesh
Any suggestions on how to get out the dark alleys I'm in now will be most
appreciated
Todd