Problem solved somehow. (Re: [Radiance-general] instance problem?)

[Gregory J. Ward]

Carsten is correct in the case of actual overlapping geometry, but 
overlapping instances are not a problem per se, though they do tend to 
make oconv take a lot longer and use a lot more memory resolving them.

If two or more instances overlap, Radiance traces rays in each 
instance, and returns the geometry that intersects first (in the case 
of multiple intersections).  If two bits of geometry are coincident, 
the one that gets returned is decided randomly, usually as a result of 
floating point roundoff errors.  The same is true when geometry is not 
contained in instances.

-Greg

> From: Carsten Bauer <cbauer- at t-online.de>
> Date: April 19, 2005 1:56:34 AM PDT
>
> Gregory J. Ward wrote:
>> It's a shame we'll never know what caused this problem, whether it 
>> was the model or a bug....
>
> Hi Greg & Lars,
>
> just guessing form afar, I think it is (was..) not a bug but a simple 
> instance overlapping problem. If several instances overlap, each one 
> will be traversed for a ray hit, and the one which actually 'wins' in 
> the end is determined by the way they're inserted into the object set 
> for this octree subcube, and not e.g by the distance of the ray hit to 
> the view point.
>
> (PS one reason for me joining into that discussion and risking a 
> statement is to check if my understanding of the meachinism is 
> correct...)
>
> -cb