On Sun, 15 Nov 1998 23:25:26 +0200, Basil S. Lewis, MD. 
	<lew### [at] txtechnionacil> wrote:
>I am now learning optics in school, and would like to point out the
>following optic errors in POV-Ray. I don't know how realistic pov is
>supposed to get, but I hope that one day these errors will be fixed.

I think "errors" is a bit too strong of a word to describe some
fundamental flaws in the raytracing model.  These are not bugs,
btw, so this discussion should be in .general (note followups)

>1) When I use media/atmospheric light effects, I don't see the light
>curving when it goes through lens. It keeps going the way it did.

The reason this happens is that raytracing traces a ray from the eye 
back to the light.  Since light can travel by many routes, it's impossible
for a raytracer to determine all of the possible routes by which light
could have arrived at the point for which it is determining the illumination.

There is a simulation of refractive caustics built in to POV, but it's 
likely not accurate enough to do optics experiments with.  There are 
statistical methods for doing this sort of thing relatively efficiently
as well, but so far none of them are available for POV.

>2) When I make a wall split to two by a small hole along its height, and
>point a light on to it, and then put a board behind, the light just
>projects a staight line (as we would expect) but does not show the wave
>property effects of light. This effect should produce dark areas across
>the board.

POV also doesn't accurately simulate some other properties of light.  For 
example: variable IOR by frequency (chromatic aberration), fluorescence, 
phosphorescence, and polarization. Nor can it simulate materials with 
spatially varying IOR. There are just some things we shouldn't expect 
from a program whose main purpose is, after all, creating pretty pictures.

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