Ben Chambers <ben### [at] pacificwebguycom> wrote:
> First of all, POV is already a forward raytracer.

  The most common agreement is that the "forward" and "backward" terms
refer to the direction in which light travels.

  In other words, a "forward raytracer" is a raytracer which calculates
how light traverses from light sources towards the scene, and from there
towards the camera.

  A "backward raytracer" does the opposite: It calculates in the opposite
direction how light travels, ie. it starts from the camera towards the
scene, and from there to the light sources. This is how POV-Ray (and
almost all raytracers) work.

  POV-Ray's stochastic global illumination algorithm is still "backwards
raytracing" because it traces from surfaces to other surfaces and from
there to the light sources (ie. it still traces back how light traverses).
POV-Ray's photon mapping algorithm is a genuine "forward raytracing"
feature.

  Of course there are some books which mix these terms, causing confusion.

-- 
                                                          - Warp

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