Thomas de Groot wrote:

> I like the idea very much as I have played also somewhat with the GTOPO30,
> and the NASA DEM data. 

Do you mean by the latter the SRTM 3-arcsecond GeoTIFFs? If you had not 
heard about them until now, the URL is 
ftp://ftp.glcf.umiacs.umd.edu/glcf/SRTM/Degree_Tiles !

My personal interest is the Iberian Peninsula by the
> way 

Entire Spain, Andorra and Portugal? A formidable task, comparable in 
size to my dreams of virtual Afghanistan!

(oh! maybe Deception Island too, which I visited, 20 years ago...).

Cool, you went skinny-dipping in Antarctica! Have you also been to South 
Georgia on that cruise? That's one of my favourite places outside 
Afghanistan...

> It is a project with ambition. I think that I would need another PC anyway
> for better data crunching (something I am thinking about seriously)... 

What machine do you own at the moment? Mine is an AMD Athlon 64 2800+, 
running at 1.8 GHz, 512 megs of RAM... probably I'll upgrade to 1 gig 
somewhen in the coming months!

and a
> lot of theoretical help too.

Yes, math is an issue... I wrote a PoV template for generating curved 
meshes (i. e. meshes that follow Earth surface's curvature) from ASCII 
height matrizes derived from the SRTM GeoTIFFs (the latter done with 
3DEM), but I'm currently totally unaware how to write an algorithm for 
optimizing the number of height samples to be taken into account for 
mesh calculation depending on the camera viewpoint...

Then we also should have a program that allows filling in the data gaps 
in the original SRTM data - 3DEM has such a routine, but it does not 
work with gaps bordering the edges of a one-degree tile!

Also, we should make use of a multi-bezier patch utility written some 
time ago by Tor Olav Kristensen to get a real smooth surface (which at a 
later stage can be "roughened up" in a controlled way to get rocky 
mountainsides etc.)

  I am really a lay person in this matter. Time
> would not be a problem, though.
> I am tempted to contribute...

Welcome aboard! Let's beat the drum together for fellow combatants!

See you in Khyberspace!

Yadgar

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