> I remember reading somewhere that a number of things in POVRay are "faked"
> for speed considerations.
>
> Could someone please tell me which things are faked, and how the "fake"
> implementaion differs from a "real" one?


The most significant "faked" thing in POV-Ray is the behavior of light. In
real life, a light source (such as the sun) emits light, which hits objects,
and then bounces into our eyes. In POV-Ray (and practically every other 3D
program), paths are traced from the eye of the camera onto objects, and then
checked to see if the path to the light source is clear. If so, color is
drawn there. This is why it's called "backwards raytracing" - because we
trace the path of light backwards, instead of forwards. This saves time
because we avoid tracing light rays that don't hit the camera.

This has its limitations, which POV-Ray works to overcome through Photons
and Radiosity. Photons are a way of tracing the light forwards, from the
light source outwards, but only in the directions which are going to make a
noticeable difference in the scene. Radiosity is still essentially a
backwards simulation, but it attempts to replicate the bouncing-around of
light which causes shadowed areas to be lit up, depending on how much light
is reaching them in an indirect manner.

 - Slime
[ http://www.slimeland.com/ ]

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