Christian Froeschlin <chr### [at] chrfrde> wrote:
> I suspected that radiosity would be the correct way to pass on the
> light but I don't think I have the knack or patience for it (yet?).
> Also, it would defeat the purpose of using double_illuminate
> instead of media to speed things up :-P

Well, not necessarily.  Radiosity is not always a punitive feature to use.  The
knack can be tricky.  I didn't touch radiosity for a very long time as it just
seemed to me to be a feature designed solely to slow down rendering and confuse
the user.  Using rad_def.inc was, for me, a good springboard to start getting a
handle on it.  I think its just one of those things that you have to play with
enough until you get a feel for it.

> Well, it works to some extent with no_shadow, which also
> allows light to escape even when not using radiosity. Of
> course the light transport is not physically correct but
> it may be a good enough approximation for some scenes
> or at least medium quality test renders. The perceived
> ratio of lamp shade brightness vs illumination power
> can be tweaked with light intensity and fade_distance.
>
> The above scene with 800x600 AA 0.3 took about one minute
> to render on a P4 2.6Ghz - and about half of that seemed to
> be spent on the floor texture ;)

Yeah, with no_shadow you're getting the light directly from inside. I think each
method has its trade offs.  For your example, you'll always have to use an area
light for soft shadows.

Just for curiosity sake I put together a demo scene inspired by your scene, with
radiosity.  The image below took 1 min 16 secs to render with AA0.01, on my 2Ghz
Athlon XP, using the stock Radiosity_Normal settings from rad_def.inc.  So,
while it depends on the scene of course, its not always a painfully big
slowdown.

-The Mildly Infamous Blue Herring

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