In article <3f5cbcbc$1@news.povray.org>,
 Florian Brucker <tor### [at] torfboldcom> wrote:
>> So a sculptor should look for a piece of stone that has the exact right 
>> colours in the right spots, and should not use paint on his sculptures?
>
>of course he can use paint. but he should not take a photo of the 
>scuplture and post process it in photo shop :)

Post-processing within a 3d program has significant advantages over post 
processing outside of the program. I think the statue/paint analogy is 
more apt than the statue/photoshop analogy. When MegaPOV had post 
processing, it wasn't just a matter of a simple filter running over the 
"surface" of the image (though that has its advantages); the filters had 
access to depth information, for example; and while I don't recall that 
in MegaPOV post processing had access to actual object information, 
there's no reason they shouldn't (i.e., knowledge about which object the 
filter is applying to when it changes pixel x).

Integrated post processing has the potential to allow us sculptors to do 
marvelous things that are either impossible or difficult directly within 
the 3D scene. Somethings are not really part of the scene, but are part 
of the resulting image. Making changes to the scene to fake out the 
renderer is certainly possible, but generally more time-consuming and 
prone to error.

One of the best examples of this for me was adding edges based solely on 
depth information; certainly, there are and have been ways of doing this 
as part of each object, but that's a hack to produce results that mimic 
what post processing can do easily, and it is more difficult to boot.

Post processing also allows much easier automation. It makes it trivial 
to automatically convert an image to greyscale, for an example that I 
used often. Again, you could certainly do so without post-processing, 
but 'trivial' is probably not the correct term, and even then you would 
be attempting to trick the renderer into doing what post-processing can 
do 'naturally': convert the *final image* to greyscale.

Post processing is probably the main reason I keep a copy of the old 
MegaPOV around.

Jerry
-- 
"Give a man a fish and you feed him for a day. Teach him to fish, and you've
depleted the lake."--It Isn't Murder If They're Yankees
(http://www.ItIsntMurder.com/)

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