From: "Christoph Hormann" <chr### [at] gmxde>
Newsgroups: povray.general
Sent: Tuesday, January 06, 2004 6:57 PM
Subject: Re: A good blurred reflection with bumps


>first of all 'per object aa settings' is not a clearly defined feature
>at all, it would be if we only had opaque non-reflective surfaces in the
>scene.  In all other cases the color of a sample is not just determined
>by a single object so you can't find a general solution for this (no
>matter how you implement it there will always be cases where it does not
>do what you want).

Well, yes, from a general point of view, and there would be cases where it
wouldn't work perfectly, probably. But in the "real" world of 3D scenes,
it's quite easy to see how this kind of feature can be extremely handy.
Let's assume that, default aa settings are usually good enough and represent
a good compromise between quality and speed (after all that's why these are
default settings). In my experience, better aa settings are often needed for
very specific situations: small regular patterns like grids, fine lines,
small letterings etc. In many cases it's a just window on a wall, a logotype
on a bottle, a plant, that sort of thing. Using high quality aa there isn't
much of a problem because the object doesn't occupy a lot of screen estate.
However, using the high quality aa on the entire scene is likely to bring it
down, because a good part of the screen space is going to be taken by the
other objects, those that were acceptable for the user with the default aa
settings but that will get "improved" anyway (I'm not talking about
quasi-uniform textures or surfaces there).
About having aa defined by zones, I think still it's much more practical to
have it defined per object. Not only it's often a object problem, as seen
above, but when doing animation that would be the only sensible way to do it
(one just doesn't want to define the zones frame by frame).

I could imagine, in an hypothetical POV-Ray, a syntax like this one:
global_settings{
    radiosity{...}
    antialiasing{...}
}

object{
    ...
    object_settings{
        radiosity{...}
        antialiasing{...}
    }
}

Note that this can already be done in POV-Ray, using several passes
(including a mask one) and an image editor (not for animation of course)...


Christoph

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