[Radiance-general] Re: rtcontrib -c

[Greg Ward]

Using -lw set to 1/(ad^ab) can be a bit extreme, but as I said you  
should set -lw no higher than 1/ad.  The smaller the value, the less  
noisy your indirect result, but a bit of experimentation on time/ 
quality trade-off is (as always) a good idea.

Cheers,
-Greg

> From: Axel Jacobs <jacobs.axel at gmail.com>
> Date: April 9, 2010 3:16:56 PM PDT
>
> Hi Andy,
>
>> I have a rules of thumb for setting -lw:
>> - to trace every ray spawned, -lw should be roughly 1/(ad^ab)  -  
>> watch out, every ray may be too much!
>> - if you have settings that produce a nice result with rpict try  
>> dividing -lw by the number of sky divisions for rtcontrib.
>>
>> I seen significant grainniness improvements by reducing -lw.
>
> Thanks for that. It's interesting that you set -lw to 1/ad^ab, not  
> just 1/ad. Will try this out. I also feel that the number of sky  
> divisions should have an impact on -ad (especially for sunny skies),  
> but I can't quite put my finger on it.
>
> Cheers
>
> Axel