In article <web.3e4118dbc7b69b7a1c4fca030@news.povray.org>,
 "Neil Conway" <nei### [at] yahoocom> wrote:

> Are multiple reflections handled by the radiosity & emitting media code?  (I
> mean multiple reflections from regular objects btw.)

The emitting code doesn't "handle" any reflections. I don't know what 
you are asking, your question doesn't make sense.


> I've read the FAQ's on this before, but I must admit I'm still somewhat
> puzzled.  A perfect mirror (unlike machined metal) should be trivial to
> handle - the direction of the ray is simply reflected about the normal to
> the mirror, after which you track it until it hits something else.  Is it
> that people want to handle imperfect mirrors?  Or is it simply that the
> angular density of the rays becomes an issue?

You seem to have a misconception of how raytracing works. Ordinary 
raytracing works by following rays backwards from the camera to a 
surface, and computing the illumination of that surface. Computing 
reflections of other parts of the scene is possible this way, computing 
reflection of light through a scene is not. Photon mapping can handle 
light coming indirectly from a light source through a reflection, but 
media does not emit photons.


> (On re-reading your paragraph above, I realise you meant specular
> reflections of light emitted from media.  However, I understood from the
> docs that specular reflections aren't really handled at all - correct?)

No, I meant diffuse reflections, handled by radiosity. POV simulates 
light emitted by media and reflected directly into the camera by 
ordinary raytracing and diffuse illumination of other surfaces with 
radiosity, but it can not simulate specular reflection of light emitted 
by media.
Specular reflection of light from light sources can be done with 
photons, but emitting media doesn't emit photons. You could spread a 
bunch of photon-emitting light sources through your media, it would be 
slow but could give a better approximation.

-- 
Christopher James Huff <cja### [at] earthlinknet>
http://home.earthlink.net/~cjameshuff/
POV-Ray TAG: chr### [at] tagpovrayorg
http://tag.povray.org/

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