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>>>>> "Christopher" == Christopher James Huff <cja### [at] earthlinknet> writes:

Jack> I expected to get a rainbow pattern on the target, but instead
Jack> the light passes directly through the prism without refracting
Jack> or reflecting in any noticeable way.

The version of the file sitting at that URL is newer than the original
post.  I had followed the photon hint and gotten a rainbow.

Christopher> Hmm...I see a rainbow. Even in the image you gave. Do you
Christopher> expect it to be spread out more?  First, your
Christopher> dispersion_samples is quite high, and your photon count a
Christopher> bit low. I dropped dispersion_samples to 20, and raised
Christopher> photon count to 5000000, the result was a clearer looking
Christopher> rainbow spot. Second, 1.2 is a pretty low ior for glass,
Christopher> I replaced it with 1.4, and raised dispersion to 1.06 and
Christopher> the light source brightness to 5 in order to exaggerate
Christopher> the effect.

Ahhh!  I was looking for how to crank up the brightness!  It's not in
the manual under "brightness", but a reread of 6.5.7.1 shows that I
just needed to crank up the three RGB values.  Sometimes I amaze
myself.  

Christopher> BTW, the maximum max_trace_level is 256, 20000 is a
Christopher> little high.

Yeah, I gathered that.

Jack> The "+A +AM2 +R7 +J" don't seem to really matter, though,
Jack> because I get effectively the same results without the added
Jack> settings, and it takes seven seconds instead of thirteen minutes
Jack> on my machine.

Christopher> It will make no difference as far as dispersion is
Christopher> concerned. As for the speed...you could probably get a
Christopher> big improvement in speed by lowering the recursion
Christopher> level. 7 is quite deep for this, lower recursions can
Christopher> usually give good results with much less of an impact on
Christopher> speed.

That's what I figured.  Thanks for the tip!

Now to figure out why pov-mode.el is disregarding the customize
settings I've made...

Jack.
- -- 
Jack Twilley
jmt at twilley dot org
http colon slash slash www dot twilley dot org slash tilde jmt slash
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