GRAUX Ludovic (LUDOVIC.GRAUX++at++siege.aerospatiale.fr)
Mon, 22 Jul 1996 15:13:36 +0200
Personnally, I have made a spheric node, with LODs and groups, to efficiently
use the culling. My triangle mesh is uniform, without consideration of
geography. I applied a fine texture of a geogreaphic planisphere.
I was inspired both by the pfdNewSphereGSet routine of the libpfdu librairy
of performer 2.0, and by the ARPA World exemple of the 'Friends' directory,
to make my own uniform model. There are nice ideas in both those examples,
but both do not adress good texcoordinates for spheric texture mapping. I
made a texcoords system by converting the latitude and longitude angles of
each vertex into texture coordinates. But I face a pb of circularity, that
makes artefacts of texture mapping particularly in the poles.
I wont try to explain in details my pb, but I would like to know where to
find a good spheric texture coordinate generation algorithm (pfTexGen doesn't
work for this).
Another item about earth model : The nasty consequence of a regular triangle
mesh is that the coasts get blurred when I get closer to the earth's surface,
even with a well sharpened magfilter.
I would be glad to find a model of the earth with a triangle mesh respecting
the coasts, and geography in general. Does anyone know where to find this ?
I hope to continue with you all this discussion about earth modelization.
Michael Boccara
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