POV-Ray : Newsgroups : povray.binaries.images : Radiosity and reflective glass : Re: Radiosity and reflective glass Server Time
24 Sep 2021 05:29:47 EDT (-0400)
  Re: Radiosity and reflective glass  
From: Chris R
Date: 15 Sep 2021 08:30:00
Message: <web.6141e6e375c5f9258b0d9fdd5cc1b6e@news.povray.org>
"Chris R" <car### [at] comcastnet> wrote:
> "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.

As promised, here is the scene with max_sample set to 10.  The artifacts are
gone.  I also took the suggestion of using a 5x5 area light for the main indoor
light.

-- Chris R.


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