POV-Ray : Newsgroups : povray.general : Possible Photon bug with scaling a scene? What settings do I need? Server Time
3 Aug 2024 12:14:00 EDT (-0400)
  Possible Photon bug with scaling a scene? What settings do I need? (Message 1 to 1 of 1)  
From: John D  Gwinner
Subject: Possible Photon bug with scaling a scene? What settings do I need?
Date: 2 Mar 2004 23:19:15
Message: <40455cc3@news.povray.org>
I'm having some odd scaling issues with Photons.

I'm attempting to model a LARGE scene with human sized elements in it during
close ups.  To make things easier with existing models I have, I'm using 1
unit = 1 meter.

I have some objects that are Kilometers long.  POV ray seems to handle this
fine, but when I use photons it's doing some weird things.

Specifically, if I model a mirror reflecting a parallel light source into an
object, if the object is small, the scene looks fine.

If I mode the *exact* same object with larger units, at first the object
that the light is reflecting onto doesn't get any light, but an infinite
plan right behind it does.  (rather odd looking).  Scaling the scene
further, the the light on the plane disappears also.

I've tried experimenting with the number of photons and the photon radius,
which helps a little, but when I hit units in the thousands everything
disappears.

I have a feeling there is a radiosity or photon setting that is below a
threshold when I start doing very large objects, which is causing the issue.

A work around would be to rescale everything I guess, but I'd prefer to find
out what I'm doing wrong.  I checked the documentation under "Photons" and
didn't see anything that was obvious other than radius, and I already tried
changing that.  (it helps a little but at some point I still have to add
many more photons).

I'll post some scenes in P.B.I to show this effect.

Thanks for the help,

        == John ==


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