Randal L. Schwartz wrote:
>>>>>> "Bob" == Bob Hughes <omn### [at] charternet> writes:
> 
> Bob> One of my favorite things about POV-Ray, such light characteristics. Great
> Bob> that it was thought of before the talk ended completely.
> 
> So Leo was right!  Cool.  I kept thinking "That's hard to program so
> it probably doesn't do it".  :)  Darn programmer in me.
> 

It wasn't in DKBTrace and early versions of POVRay.  Since raytracing 
traces light rays backwards from the eye towards the world, when the 
light goes through a prism, you'd have to split one ray into lots of 
other rays with different colors.  This seems to be what the POVRay 
dispersion feature does.

The other complication (which POVRay tries to fake) is that the rays in 
a raytracer only track three colors - red, green and blue.  In the real 
world, light is (generally) a blend of lots of different wavelengths. 
To get truly accurate results, we should model the light as a bundle of 
wavelengths.  Each surface will reflect some wavelengths, absorb others, 
and scatter others.  When we calculate the final wavelength bundle for a 
pixel, we can then map it onto RGB.  POVRay cheats by only assuming that 
the light only contains 3 wavelengths.

David Buck

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