Ken wrote:

>   One major disadvantage of the Pov lighting model is that is does not accurately
> reflect the true color temperature of a light source. Fluorescent lights are a
> good example of this limitation and is clearly visible if you have ever tried
> to use fluorescent lighting in real world photography. The light emitted by a
fluorescent lamp is
> full of gaps in the color spectrum. It has some red, skips
> 12 bands, has some green, skips 30 bands, has some blue (quit a bit really),
> skip some more...

This problem might be worked around by taking into account that povray
does not care about the real color - it just does 3 components with each
ray. One might sample the spectra of the lamps at N (sufficiently
densely
spaced) wavelengths, and run povray N/3 times, giving at each run the
lamp intensities resp. object ref[lr][ea]ctivities for the three
wavelengths used in this run, and finally mix the N/3 output images
(using e.g. ppmarith(1)) using the r/g/b sensitivity curves of the human
eye. Of course, this approach is awkward.

Using only 3 color channels, no program would be able to 
show the lamp-dependent impression of objects with metameric
colors.

I guess the main problem for real world lighting applications
might be the radiosity effects, which (in places properly lit
for humans) dominate. I don't know how perfect the radiosity
implementation in povray is.

Ralf

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