POV-Ray : Newsgroups : povray.binaries.images : Radiosity and reflective glass : Re: Radiosity and reflective glass Server Time
22 Sep 2021 05:07:57 EDT (-0400)
  Re: Radiosity and reflective glass  
From: Chris R
Date: 14 Sep 2021 16:15:00
Message: <web.6141026775c5f9258b0d9fdd5cc1b6e@news.povray.org>
"Chris R" <car### [at] comcastnet> wrote:
> Alain Martel <kua### [at] videotronca> wrote:
> >
> > > I have been working on a scene modeling the bar and glassware cabinet in the
> > > corner of my living room.  When testing the addition of new elements to this
> > > scene I render it at various anti-alias levels with radiosity turned off, and
> > > I'm pretty happy with it.
> > >
> > > When I turn radiosity on (using Rad_Settings(Radiosity_IndoorLQ, off, off)), I
> > > get all of these extra highlight spots on the curtains, the rug, and the frames
> > > around the window.  I verified that if I leave the glasses out of the cabinet,
> > > those highlights disappear, so I'm pretty sure it has something to do with the
> > > reflective glass surfaces interacting with radiosity.
> > >
> > > The problem is that I'm not sure how to fix this.  The typical finish on the
> > > glassware is something like this:
> > >
> > >          finish {
> > >              specular albedo 0.05
> > >              roughness 0.0005
> > >              reflection {
> > >                  0.1
> > >                  fresnel
> > >              }
> > >              conserve_energy
> > >          }
> > >
> > > and the interior:
> > >
> > >      interior {
> > >          ior 1.6
> > >          caustics 1.0
> > >          fade_distance 2*Hurricane_glass_base_radius
> > >          fade_power 1001
> > >      }
> > >
> > > There is a sun-based light-source outside of the room, but it is positioned such
> > > that it is probably not adding any highlights to the scene.  The lamp on the bar
> > > itself is very low power, but does have an emission value in the finish of the
> > > lampshade.  The main light source is a cluster of 4 bulbs, each modeled as a 2x2
> > > area light behind, above, and to the left of the camera.
> >
> > Should be at least 5x5, preferably 9x9, with adaptive 0.
> >
> > >
> > > Any thoughts on what I am doing wrong that is causing these to appear?  No
> > > matter how bright a light I add to the actual room, I do not see these
> > > highlights on the curtains or the rug.
> > >
> > > Thanks,
> > >
> > > -- Chris R.
> > >
> >
> > I often see similar highlights IRL. So, they look natural.
> >
> > Whenever you have reflective or refractive surfaces in a radiosity
> > scene, they act the same way photons do : Cause highlights and caustics.
> > The mechanism causing them is different, but the end result can be similar.
>
> I am currently running a portion of the scene where I used Radiosity_IndoorHQ to
> see if better radiosity settings would eliminate the blotches.  It's been
> running for 2 hours and is about to start tracing, but I think I am still seeing
> the highlights, so that probably isn't the problem either.
>
> One thing I failed to mention earlier is that the indoor light source was
> created using LightSys, using its color calculator and fading.  This always
> results in very bright light colors to make the fading work.  I am wondering if
> that means I should be using a "max_sample" setting in radiosity?
>
> -- Chris R.

I'm mostly talking to myself here, but it turns out that setting max_sample to a
non-default value has removed the unwanted lighting artifacts.  I am currently
using 10 for max_sample in the scene and rendered it with the Radiosity_Fast
settings and the artifacts went away.  I'm rerendering the scene now with better
indoor radiosity settings and will repost the image here to show the difference.


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