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Howdy-ho!
I have a question about AA. The "standard" in POV-Ray is set at 0,3, and I
can change it myself by adding i.e. +A0,1 to the command line. But I wonder
what limitations there are to this? Can I put +A0,00000000001 or something,
or will there be no difference? Please enlighten me!
In all humbleness
RH
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Wasn't it RusHHouR who wrote:
>Howdy-ho!
>
>I have a question about AA. The "standard" in POV-Ray is set at 0,3, and I
>can change it myself by adding i.e. +A0,1 to the command line. But I wonder
>what limitations there are to this? Can I put +A0,00000000001 or something,
>or will there be no difference? Please enlighten me!
>
>In all humbleness
The documentation says:
In the default, non-recursive method (+AM1), POV-Ray initially traces
one ray per pixel. If the color of a pixel differs from its neighbors
(to the left or above) by at least the set threshold value then the
pixel is super-sampled by shooting a given, fixed number of additional
rays. The default threshold is 0.3 but it may be changed using the
Antialias_Threshold=n.n option. When the switches are used, the
threshold may optionally follow the +A. For example +A0.1 turns anti-
aliasing on and sets the threshold to 0.1.
The threshold comparison is computed as follows. If r1, g1, b1 and r2,
g2, b2 are the rgb components of two pixels then the difference
between pixels is computed by
diff = abs(r1-r2) + abs(g1-g2) + abs(b1-b2)
If this difference is greater than the threshold then both pixels are
super-sampled. The rgb values are in the range from 0.0 to 1.0 thus
the most two pixels can differ is 3.0. If the anti-aliasing threshold
is 0.0 then every pixel is super-sampled.
So the furthest you can push it with the non-recursive method is +A0.0.
The recursive method +AM2 goes much deeper, and takes longer.
--
Mike Williams
Gentleman of Leisure
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demon