"Jelle Duives" <jel### [at] tnonl> wrote:
> For a project we're using povray 3.7 rc6 to render a scene. For this scene (a
> scene with some houses, road & cars) we enabled radiosity in order to get more
> realistic images. However, when enabling radiosity, we observe a flickering
> effect of lights, a sort of 'disco' effect. Do you have any idea where this
> effect comes from and how to reduce this effect?
>
> Regards Jelle

clipka <ano### [at] anonymousorg> wrote:
> Am 05.09.2013 15:57, schrieb Jelle Duives:
> > For a project we're using povray 3.7 rc6 to render a scene. For this scene (a
> > scene with some houses, road & cars) we enabled radiosity in order to get more
> > realistic images. However, when enabling radiosity, we observe a flickering
> > effect of lights, a sort of 'disco' effect. Do you have any idea where this
> > effect comes from and how to reduce this effect?
>
> Radiosity isn't perfectly accurate, and may over- or underestimate the
> illumination in any given region of the image; if radiosity samples are
> not carried over from one frame to the next (which is the default), this
> may lead to visible random fluctuations in the brightness.
>
> If you don't have any moving elements in your scene (i.e. the animation
> is just a fly-through), this can be avoided by saving and restoring the
> radiosity samples from frame to frame.
>
> If you have stuff moving around, currently the only solution to the
> problem is to crank up the radiosity quality, to make the fluctuations
> as "shallow" as possible.

When rad is calculated each time and each scene is differently, even slightly,
it may come up with different results which causes the flickering effect.

The best way to handle this is to run a scene where you have a maximum view of
the entire scene (can even try to use some well placed mirrors to help) and run
with high radiosity settings and save the rad file.  You now should be able to
run the scene from your original view but load the rad file instead of
recalculating.

This should work better as the way rad is calculated and determined is dependent
upon the view when, but when it is save and reloaded, the view no longer matters
as it is mapped to the scene the same every time regardless of the new camera
view.  The only thing is areas that were hidden or occluded from the original
view may not get full rad effects which is why you want a setup that lets you
see as much of your scene as possible at one time.

I did a trick scene a long time ago (can't find it now) where I ran a rad scan
with a bunch of coloured balls, but then loaded the rad file with white balls
for an interesting colour cast effect.

-tgq

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