I wonder if anybody on this list could offer their wisdom...

I've noticed funny artifacts from a scene loaded from a 3ds file and I'm
trying to figure out if it's something wrong with my loading or with the
3ds file or ...

In the following picture:

   http://www.deviantart.com/deviation/56860828/

(click on the picture to get a larger image; sorry about the low quality
rendering, but hopefully it's clear enough to see what's going on)

The right mirrored sphere is loaded from a 3ds file (it looks to be
tessellated with about ~25 slices x 32 wedges). Notice that it has weird
artfacts -- reflections in this sphere are distorted with a sort of
"herringbone" pattern.  I've never seen this sort of distortion before.

The left mirrored sphere is tessellated by my own code, using the most
obvious algorithm and an even coarser tessellation (12 slices x 16
wedges). Despite the coarser tessellation, it has far fewer obvious
artifacts, (and even the artifacts it does have are "unobjectionable",
well except for the ugly silhouette).

The vertex normals in both spheres are calculated using the same
simple algorithm which just averages the face normals (I don't use the
lib3ds normal calculation).

The basic scene geometry and environment map are from Christian Bauer:

   http://hdri.cgtechniques.com/~sibenik2/
   http://hdri.3dweave.com/library/

In the renderings from this model on Christian's site, the mirrored
sphere looks fine, so I don't know if it's an error in my 3ds loading or
some problem with the 3ds file...?  I think the 3ds file was converted
from some other format, so perhaps there was a problem in the
conversion?

Any ideas what could be going on?

Thanks,

-Miles

-- 
Fast, small, soon; pick any 2.


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