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

Your system date is off a day.

I was working with fog in a recent image after trying unsuccessfully
to get atmospheric media to work the way I wanted and thought
to myself on more than one occassion how now it would be to
be able to constrain the fog feature into a specific volume of space
like you can media. The particle size used in the fog function is
very nicely uniform in size and the density is controllable through
filtering and transmission values. A few enhancements and more
user control over that feature would make for great smoke,
clouds, and various other similar items that have no real substance.
The feasibibility of such an undertaking I no not but I can dream.

--
Ken Tyler

tyl### [at] pacbellnet

Post a reply to this message