[Radiance-general] Assistance required with Rendering error / random numbers

[Peter Apian-Bennewitz]

Carsten Bauer wrote:

>if you and Greg ascertain that there are calculational advantages (mainly 
>speed) in using distributed random numbers will believe it., although I 
>haven't noticed a considerable slowing down so far. And I cannot confirm at 
>all the mentioned strong effect on necessary picture size before downsampling 
>If the relevant parameters are set correctly, I've made very good experiences 
>with the -DMC version. For printing, one can even get along with 
>downfiltering by a factor less than two, provided the image itself is big 
>enough in absolute pixels. But adequate parameter setting is of course vital.
>
Well, - stratified Monte Carlo does have advantage (lower noise and 
faster convergence speed). "Pure" MC might be feasible per combinations 
of computers and projects, but I still see it's worth considering other 
strategies for evenly spread random numbers in Radiance.

>Additionally, when considering PCs becoming faster and faster, I wonder if 
>there's a reasonable way to overcome the MonteCarlo mess completey and 
>establish a completey different, 'deterministic'  treatment of the problem 
>
A better, yet general, numerical integration would be appreciated by a 
few ...

In specular hightlights and ambient calcs the integrant is stepwise 
defined, non-functional with only very roughly pre-known boundaries. All 
I see as further enhancement is a better adaptive method. All one can do 
with a unknown integrant is to use already gained information as 
"intelligently" as possible. Educated guesses.

It might be well worth looking at the integrant more closely, though. 
Some statistics on the integrant found in all the sceneries of light 
simulations might show some patterns that suggests optimizing the 
integration method.
This proposal is not very scientific, but, RISC CPUs 
("reduced-instruction-set") where suggested by the statistic that only a 
fraction of the many complex instructions of older CPUs was ever used.

-Peter

-- 
 pab-opto, Freiburg, Germany, www.pab-opto.de