Alain <kua### [at] videotronca> wrote:
> Le 19-06-11 à 22:36, Mike Horvath a écrit :
> > When radiosity is enabled, there are multiple passes in a render, with
> > each pass rendering smaller and smaller boxes until it reaches 1x1 pixels.
> >
> > Can this be disabled so that I can go straight to the final pass?
> >
> > Thanks
> >
> >
> > Michael
>
> You don't want to do that unless you are loading radiosity data saved
> from an earlier render. In that case, use pretrace_start 1 pretrace_end
> 1 in the radiosity block of the global_settings.
>
> If using UberPOV, you can use no_cache in the radiosity block. The image
> WILL look somewhat grainy and the render will take more time.
>
> The other option is to fiddle with pretrace_start and pretrace_end.
> If you set both to 1, you'll only get a full frame block before the
> final render pass. This will result in an image of uneven quality and
> probably splotchy.
>
> Normally, it don't reaches 1x1 pixel during the pretrace steps.
> The pretrace is used to collect radiosity samples over the whole scene.
> Otherwise, the rendering of the first pixels will only benefit from a
> very restricted set of radiosity data, while pixels rendered later will
> benefit from the data collected by the early parts. The result is an
> image with a mixture of low quality sampling and high quality sampling.
>
> The defaults are :
> pretrace_start 0.08
> pretrace_end 0.04
>
> For good quality/final renders, you should reduce pretrace_end. Good
> values are in the 0.01 down to 0.0025 range. You can also reduce
> pretrace_start down to 0.02 in those cases.

What you can do, is disable what is called the "Vain Pretrace".  Then the
radiosity passes will only do a luminosity map (I think that's what it's called)
and skip the expensive color passes which have no effect on the final result.

To do this, you can add -RVP to your command line.

Regards,
A.D.B.

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