Hi Gilles! Thanks for the fast response.

> Other people will explain the details, but differencing many objects from
a
> main one is not very efficient and leads to long render times. The trick
is
> to cut the object in several pieces, have 1 or 2 difference per piece and
> then union{} the pieces. Of course, this is not always possible but any
> repeating objects such as windows should be treated that way whenever
> possible.

And this is one of those cases where it wouldn't be practical. My model has
some pretty complex shapes other than cylinders which have transparencies,
and differencing those shapes into pieces ground my workstation to a halt
(some of the shapes are sheared with matrix{} and differencing something
that has been matrix-sheared didn't seem to work too well).

> Experience shows that image_maps are very efficient so it's not really
> surprising. The worse that can happen is RAM trouble.

I guess that makes sense... why calculate a hole when you can look it up in
a static bitmap? As for memory, my workstation has 2 GB of RAM so I don't
think memory will be a problem.

> About the jaggies, did you try interpolate 2 on the maps ? It can help
> sometimes.

I knew I forgot to ask something in my original message... yes, I did try
interpolation and method 2 (bilinear interpolation) seems to give the best
results as the POV-Ray help file suggests. I still get better results going
with a higher-rez bitmap, but only for extreme closeups, so I'm content to
create two sets of image and bump maps (one set of low-rez maps for
animations and distance shots, and one high-rez set). But here's the
thing... when interpolation 2 is selected for all of my image/bump maps, the
rendering time slows down only slightly (very nearly within the range of
statistical insignificance, from the 10 test runs I performed) over using no
interpolation at all. So my question is, why would you *not* want to use
bilinear interpolation on your image and bump maps?

Thanks!

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