Op 6-6-2022 om 16:50 schreef Alain Martel:
> 
> In a case like that, it's very interesting to use the importance feature 
> of the latest versions.
> 
> It's used as follow :
> You start by assigning a default importance weight to everything with a 
> #default statement :
> #declare HighSamples = 50000;
> #declare AverageSamples = 75;
> #default{rediosity{ importance AverageSamples /HighSamples }}
> 
> Then, for the objects to be used as light sources, you add :
> radiosity{ importance 1 }
> usually just before the closing brace or just before the texture 
> definition.
> 
> In cases like this, I tend to also use the adaptive nearest_count :
> nearest_count 20 3
> 
> #declare HighSamples = 50000;
> #declare AverageSamples = 75;
> #default{radiosity{ importance AverageSamples/HighSamples }}
> 
> global_settings{ assumed_gamma 1
> radiosity{
>   pretrace_start 64/image_width
>   pretrace_end   4/image_width
>   minimum_reuse 4/image_width-0.05
> 
>   count HighSamples
>   nearest_count 20 2
>   error_bound 0.2      // this should be smaller
>                         // if you use radiosity emission
>                         // as a light source
>   recursion_limit 4
>   low_error_factor 0.35
>   media off
> 
> }
> <other optional global_settings stuff>}
> 
> That cause the average number of samples used to be about 75 for most f 
> the scene, but to be up to 50000 when sampling the area near the high 
> emission objects.

This is very good advise! Note that you may have to crank-up your 
emission value way beyond 1. For a rapid test, I used emission 1000 
together with diffuse 1, for instance.

-- 
Thomas

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