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..)

Steve


Mike wrote:
> 
> It's really just a function of the sampling.  If you recall the
> particular look of atmosphere, it had a distinct banded look.  Even
> though it was way off, it tended to look smoother because it was so in
> at least on direction.  But that was just because it sampled at equal
> lengths along the viewing ray.   Using jitter gave it a look similiar to
> media.
> 
> The grainyness is objectionable though.  Something I've been thinking
> about is that there must be some way to smooth media without taking
> extra samples.  I figure it should involve comparing pixels and trying
> to balance them.  I suppose a new keyword could let the user control
> this by allowing the user to give a maximum intensity difference that
> the pixels should be smoothed.  The maximum for 24 bit images should be
> 1/255, but higher values would likely be specified.  Perhaps the sampled
> pixels could be grouped into fours and cached, then they could be
> compared against each other.  Then the intensities would be adjusted
> until neighboring pixels don't vary by more than the specified amount.
> 
> I've heard that similiar techniques are used for stachastic renderers
> for the same reason.  There is a certain loss of accuracy, but it
> doesn't require much extra time and results in more visually pleasing
> images.  If you take that image and draw a freehand mask around it in a
> paint program, then apply a gaussian blur to the image, I bet the
> results would be very nice.
> 
> comments/flames?
> 
> -Mike
> 
> Ken wrote:
> 
> >   I too will avoid comment on the specifics of this scene which is
> > note worthy in and of itself but one thing concerns me about this
> > image and other recent image postings using the new media feature.
> >   That concern is the grain structure that seems to be an inherent
> > artifact of the process. While not as pronounced in the smoke of
> > the above mentioned image, probably due to it's distance, it really
> > shows up often in many other images. I wonder if this is going to
> > be a fact of life with this feature or if there is a something that can
> > be done to reduce the particle size while maintaining the density
> > needed for realism.
> >   Smoke paticles are very fine particulate matter and the reason it
> > appears to us as it does is primarily due to shear volume. Might this
> > grain artifact be a problem of image resolutions and screen capabilities
> > or am I just jumping the gun on this still evolving feature ?
> >
> >   I'm willing to entertain discussion on this but truthfully have as yet
> > not spent much time with it and am by no means a barometer of
> > it's potential.
> >
> > --
> > Ken Tyler
> >
> > tyl### [at] pacbellnet

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