Warp wrote:
> 
>   As far as I have understood, the algorithm goes approximately this way
> (Nathan, please correct me if I say anything wrong):
> 
>   The lighting values of the radiosity calculations are stored in a spatial
> tree.
>   When the lighting of a certain point is calculated povray first looks if
> the point is close enough to a point in that spatial tree. If it is, then
> it just takes some closest points in the tree (I think that the number
> is specified with 'nearest_count') and calculates a weighted average of
> their illumination values.
>   If there isn't any point close enough, then it shoots lots of rays
> in every direction (well, not in every direction but only through the
> hemisphere which is defined by the surface normal vector). If the recursion
> level is 1, then it just takes those values the rays hit. If the recursion
> level is higher than 1, then it performs this same algorithm for each
> intersection point.

Okay, that sounds about right.

Here's what's bothering me, though: I have a small room with no
traditional lighting and a rad source (1/8th of a three foot radius
sphere with ambient 8 or so) in one corner, and the light it shines on
the far wall is decidedly splotchy, even with the nearest_count pumped
to 20 (the max) and the count cranked up to 600 (I really don't want to
go higher, as it's already slow enough, and *shouldn't* have to).

It occurs to me that if the radiosity algorithm is shooting out random
rays, then although they should average out, they may not be doing a
very good job of it, and I wonder if it would work better with some kind
of even distribution pattern.

It might be worth looking into other ways to tweak the algorithm as
well, but for now that sort of thing would be over my head.

-Xplo

Post a reply to this message