Andreas.Ekstrand++at++saab.se
Fri, 03 Jul 1998 14:27:06 +0200
I have a problem trying to map satellite textures on an ASD
terrain mesh. I have also observed this problem when mapping
textures on an "ordinary" static terrain mesh. The polygons
match perfectly so the texture mapping must be the problem.
The texture images themselves also match perfectly when I
watch them unmapped. But as soon as Performer maps them on
to the polygons there is disturbance between these texture
pieces.
My satellite textures are 2048x2048 each and between these
pieces you can observe an annoying miscolored line when they
are mapped. I figure this is due to Performer's method of
interpolating, or blurring, the texture pixels to texels so
they cover the whole surface. I have come the the conclusion
(right or wrong?) that Performer filters the texture with some
kind of average kernel, and that in the outer borders of the
texture the pixels are blurred with the pixels on the opposite
side of the image. This way unwanted lines with different colors
appear between the texture pieces and in the outer borders of the
terrain.
Is there anyone who knows how this phenomenon can be avoided?
I guess one either would want to totally eliminate the average
filtering between the different texture pieces, or perhaps it
would be even better if one could just avoid filtering the pixels
with the ones on the opposite side.
I know that some parts of my explanation of the problem might
sound a bit confused or mixed up...if so, please ask me to try to
describe these parts better. I sure hope somebody recognizes this
problem and has a solution.
Sincerely,
Andreas Ekstrand, SAAB Simulation Centre, Sweden
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