In article <399### [at] kivisalonet>, Kari Kivisalo 
<kar### [at] kivisalonet> wrote:

> u is the density/potential at (x,y,z).

Simply the field value? Then this is nothing more than a kind of 3D 
convolution matrix...right? Basically a blurring operation.


> > Does it require that the density field be converted to a voxel image? 
> 
> As I said before this algrithm is a numerical discrete approximation,
> not analythical. The input and output are are voxel images just like
> the 2d case works with 2d images. Only certain special cases of potential
> fields can be solved analythically at any point. The whole volume must
> be solved at once so it's impossible solve just one point at a time.

Are you sure about this? It seems like some kind of recursive algorithm 
could be used to do a similar effect, sampling at one distance, 
subdividing and interpolating, sampling again, etc. I am going to have 
to experiment with this...
It wouldn't be the same algorithm, but it should be similar in results.


> In povray terms this requires a pre-rendering pass to sample the volume
> of interest at specified resolution and then solving the potential field
> within that volume.

This could most easily be done in the parsing stage, and would probably 
be a density_file pattern internally. However, you would have to specify 
a resolution large enough, and it would consume a lot of memory. :-(
If this absolutely requires a voxel image, then might as well implement 
it as a density_file feature, and add the ability to create a 
density_file pattern from another pattern(like object). You could 
already do so with a macro and eval_pattern() or eval_pigment(), but the 
parse time would be long.

-- 
Christopher James Huff - Personal e-mail: chr### [at] maccom
TAG(Technical Assistance Group) e-mail: chr### [at] tagpovrayorg
Personal Web page: http://homepage.mac.com/chrishuff/
TAG Web page: http://tag.povray.org/

Post a reply to this message