Saw the movie, it was fun to see.
Think I saw the same "voxel" wepage you did, had a few cloud examples.
Seems to me it was by a person making their own program to do that too.
POV-Ray could probably come close to it, in fact the few great examples
I've seen done were decent enough.
The biggest difference may be in render time most of all. And admittedly
maybe the present 'media' can not achieve the same results anyhow.
Simply unknown to me so far.
Peter Popov's adventuring into particle media is a good example too. At
least I think it was Peter.


Equiprawn wrote:
> 
> Then I remembered seeing a webpage a year or two ago that gave examples of a
> method of rendering clouds using things called voxels. These voxels not only
> let you have realistic cloud shapes, but let them be shaded by light
> sources, and be misty and insubstantial, so you could fly through them. The
> cloud examples on the page were very impressive. Unfortunately, I have no
> idea of the address of that page.
> 
> I did a hunt on the web last night for pages on voxels, and I cam across an
> interesting one at
> http://www.uni-koblenz.de/fb4/publikationen/gelbereihe/GelbeReihe.bib . On
> this page, there is an abstract on a paper that reads :
> 
>    "In this report we present a volume rendering technique
>     embedded into a customary ray tracing scheme which is able
>     to visualize arbitrary particle densities perceived as
>     realistic clouds of different types found in nature.
>     Moreover, this technique can be abused to visualize
>     phenomena like fire, steam, haze, dust or other gaseous
>     effects in the atmosphere. Our volume rendering strategy
>     utilizes the volume sampling method, i.e. it computes an
>     image by successively sampling voxels along the current ray
>     and it progressively adds the voxel's optical contribution
>     to the final picture in accordance to the physical laws of
>     scattering and absorption."
> 
> This got me wondering exactly how close in Povray's media engine to a voxel
> engine? Those last two terms, "scattering" and "absorption" are already part
> of Povray's media implementation. Is Povray's media a voxel engine? If it
> isn't, would it be more useful and powerful if it was a voxel engine? As far
> as I can make out, voxels give you much greater control over the shape of
> your voxel container, and seem to give very smooth and accurate results.
> 
> If you want to see some examples of what voxels can do, take a look at
> http://www.newtek.com/products/lightwave/hv2/hv2.html . This is a Voxel
> plugin for Lightwave 3D (please don't kill me! I know it's a scanline
> renderer, but it was the only visual example of voxels I could find), and I
> think you will see how powerful voxels can be.
> 
> So in summary, my questions are:
> 
> 1) Is Povray's media engine a voxel based engine?
> 2) If it is, then how come the images on the Lightwave 3D page look much
> cleaner and more realistic than I have ever seen Povray do?
> 3) If Povray's media engine isn't a voxel based engine, what would be the
> benefits of converting it to one (ie, do voxels have any benefits over the
> current media implementation)?
> 4) Would it be difficult to implement this in a raytracer, or specifically
> in Povray?
> 

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