POV-Ray : Newsgroups : povray.text.tutorials : Radiosity Voodoo - Volume 1: How Radiosity Really Works : Re: Radiosity Voodoo - Volume 1: How Radiosity Really Works Server Time
27 Nov 2021 22:20:43 EST (-0500)
  Re: Radiosity Voodoo - Volume 1: How Radiosity Really Works  
From: Christoph Hormann
Date: 21 Jan 2009 02:29:50
Message: <4976ceee$1@news.povray.org>
clipka schrieb:

> I guess it's time to sum up a few things I have learned both during
> experimenting with POV-Ray radiosity, and digging through (and tampering with)
> the source code. So here comes volume 1 of my "black magic" tome. I fear it's
> still as flawed as the 3.6 radiosity code was (I confess I didn't bother to
> read it again after hacking it in), but it may give you some insight already:
> 
> [...]

This is a very comprehensive description of radiosity workings in 
POV-Ray but i think you are mistaken about one central point:  The 
radiosity pretrace will not be able to (and was never designed to) take 
all samples necessary during pretrace in a real life scene.  The main 
reason is that a scene with edges and corners in the geometry (i.e. 
surfaces with infinite curvature) will require an infinite sample 
density at these corners and unless you do not shoot any camera rays 
during the final render pass that have not yet been traced during 
pretrace (and this usually always happens - aa, jitter) you will need 
additional samples in the render.  To avoid this practically you would 
have to raise the error_bound during final trace by a huge amount 
(possibly adaptively like possible in latest megapov).

-- Christoph


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