I've done a bit of research into terrain modelling (and I'll be doing some 
more), so some comments:

To get CLOD working the scenery engine has to revert to regular spaced 
elevation grids. TIN's are too slow for CLOD terrain (the insert / remove 
algorithms are the main slowdown, regular spaced grids are usually based on 
quadtrees which will just work faster). The most recent trend is to use 
fast insert/remove algorithms that not necessarily minimise the number of 
polygons. The reason for that is that modern graphics cards (Geforce, 
Radeon, etc) are capable of rendering > 1,000,000 polys per sec, so older 
CLOD algorithms like ROAM are too slow.

Roads, etc should really be done with decals, or as a second texture layer 
that get's mapped on top of the first one. I don't like how M$ solved it in 
FS2002, I'll look into this at some stage, because I'll have to do it for 
my work anyway, and I'll report here on my progress...

Cheers, Christian


At 08:32 PM 22/07/2002 -0400, you wrote:
>James A. Treacy writes:
>
>  > This brings up something I've been wondering for a while. It appears we
>  > can add roads and rivers. Why, then, isn't this the default?
>
>Unfortunately, to get roads, railroads, and rivers, we have to give up
>some quality in the terrain mesh.  You don't notice much in flat
>terrain, but sometimes the mountains come out looking funny.
>
>
>All the best,
>
>
>David
>
>--
>David Megginson, [EMAIL PROTECTED], http://www.megginson.com/
>
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