POV-Ray : Newsgroups : povray.binaries.images : Radiosity and reflective glass : Re: Radiosity and reflective glass Server Time
18 Oct 2021 23:21:55 EDT (-0400)
  Re: Radiosity and reflective glass  
From: Chris R
Date: 14 Sep 2021 14:05:00
Message: <web.6140e32275c5f9258b0d9fdd5cc1b6e@news.povray.org>
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.


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