TonyB wrote in message <37A887CF.A622BAAF@panama.phoenix.net>...
>What is a depth map?

I don't know if there is a standard definition
of a depth map, but I'm interpreting it in this context
as a 2D array of all the intersection data generated
by a raytracing pass. For every screen pixel, a
block of information is stored that tells what
object (objects?) contributes light to that pixel,
what the intersection point and surface normal
on the object is, etc. Once a depth map is built,
another routine (what I call a colorizer for lack
of a better term) goes through the depth map and
plots the screen pixels.

The depth map is essentially a cache of the
raytracer's scene object intersection data. It
lets colorization occur rapidly afterwards
despite changes in the scene, as long as the
camera position or viewport size is not changed
(there are other qualifiers, but I don't want
to make this post overly long).

Ray Gardener
Daylon Graphics Ltd.
http://www.daylongraphics.com/
"Heightfield editing perfected"

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