[Radiance-general] Instances

[Greg Ward]

Hi Lucio,

> Thank you so much for your detailed answer (and sorry for being late again exploring it). 
> 
> -aa method is a good one, but I am a little concerned this will impact a lot on rendering time in a scene like mine in which many ab are required and a very high number of rays (it is a comparison between shading systems to work out transmittances).

It doesn't necessarily take as long as you might expect, because the ray tree is very sparse after the first bounce (depending on the -lw and -ld settings).

> The -PP option seems to be what I need, but I am not sure I understand it. Please tell me if the following is correct.
> 
> I start an rpict (or rtrace) with a -PP namefile option.
> 
> I start other rpict or rtrace wit -PP namefile (the same) and they will share memory (ram?)

Correct, although new ambient values will not share RAM.

> Ambient file instead will be shared by using -af and the same ambient file for all the processes.

This will share the values themselves, which is critical for speed if -aa is not 0, but they will take additional memory in each process.

> I believe -S is not needed with the -PP option, am I right?

With rpict, you need to couple -PP with -S.  The rpiece program takes care of dividing a single image into pieces if that is your desire.

> Can I share with -PP between rpict and rtrace processes?

Regrettably no, you need a separate syncfile for rpict and rtrace, as they are different executables.

Cheers,
-Greg