Stephen Lavedas wrote:
> 
> About Atmospheric banding... I had problems with that even though I set
> sample VERY high... then I realized that since I was running my Desktop
> at 16bit color, I was viewing a 24bit image, undithered at
> 16bits...Changing my Desktop to 32bit cleared up the banding.  Just a
> comment (it doesn't fix the media grain artifact, but I must believe
> that this graininess can be used somehow..)


The problem with the image in question (FSaP) is clearly not color
discritization....

The problem is the simple Monte-Carlo technique used by POV.  Each pixel
has the integral calculated independently from its neighboring
pixels.  This is wasting information.  More sophisticated Monte-Carlo
techniques can be used, with introduction of potentially considerable
complexity, which make use of the generally smoothly-varying nature
of the media fields.

The problem reminds me of the one in semiconductor device processing,
where Monte-Carlo is being used to predict the distribution of ions
which result from the bombardment of semiconductor device surfaces
with charged dopants.  Some excellent results were demonstrated
at the latest International Electron Device Conference in San Francisco
of the use of some clever but relatively simple techniques to get
more out of each randomly sampled ion event.  For example, one can
do "particle splitting" in which more than one particle shares part of a path,
but then part way through is split into multiple particles to generate
different random paths.  But I digress....

The improvement of the interior methods would make an excellent
subject for a patch.

Dan


-- 
http://www.flash.net/~djconnel/

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