-----BEGIN PGP SIGNED MESSAGE-----
Hash: SHA1

Mike Williams wrote:
> Wasn't it Nicolas Alvarez who wrote:
>> Nicolas Alvarez wrote:
>>> It will supersample even if there is a completely color.
>> OK that got messed up... I meant "It will supersample even if there is a 
>> completely plain color." Even if your whole image is the exact same 
>> color, +a0.0 will supersample it...
> 
> It is sometimes useful to supersample images for which the colour is
> exactly the same at integer pixel positions, but which have sub-pixel
> features.
> 
> For example:
> 
> camera {location  <0,0,-10> look_at 0}
> 
> plane {z,0 
>   pigment {gradient x
>     colour_map {[0.005 rgb 0][0.005 rgb 1]}
>   }
>   finish {ambient 1}
> }
> 
> If you render that with any non-zero antialias threshold then it will
> miss some of the lines where the line happens to squeeze between pixels.
> How many lines are missed depends on the image size: at 320x240 all the
> lines are missed.
> 
> If you render it with +a0.0 then it finds all the lines.
> 
> That's a bit of an extreme example, but it's possible to encounter the
> same sort of effect in real scenes.
> 
	In that case, render at a higher resolution with +a0.1, then
downscale the image with an external tool. This will be faster than
+a0.0 for an equivalent quality.

		Jerome
- --
+------------------------- Jerome M. BERGER ---------------------+
|    mailto:jeb### [at] freefr      | ICQ:    238062172            |
|    http://jeberger.free.fr/     | Jabber: jeb### [at] jabberfr   |
+---------------------------------+------------------------------+
-----BEGIN PGP SIGNATURE-----
Version: GnuPG v1.4.7 (GNU/Linux)

iD8DBQFGyxoId0kWM4JG3k8RAjczAJ91+3ApROl9yf0S3O8Hxx/Ng89fGwCfcV8x
ePvr5YKDAmvurTcn772pIcc=
=y667
-----END PGP SIGNATURE-----

Post a reply to this message