In article <3c73fc36@news.povray.org>, Micha Riser <mri### [at] gmxnet> 
wrote:

> I am experimenting with new antialiasing methods for povray. Now I am 
> looking for scenes where the current methods do a poor job or need too many 
> samples/pixels to produce a nice result. If you have such a scene which is 
> not too large (<100kB) and does not take hours to render please send it to 
> me (mri### [at] gmxnet) or post it to p.*.sf. I will then test if my new 
> implementations do better than the old ones.

BTW, looking through the old Ray Tracing News archives, there's plenty 
of information about this...one interesting method was to make a hash 
value from the objects intersected and shadow rays. If the hash value 
changed from one pixel to another, either the set of objects hit 
changed, or the image passed into/out of shadow. Then the colors were 
compared, and the pixel was only antialiased if the hash changed and the 
color was different. No antialiasing the tail of a black cat on a 
moonless night, but only object/shadow edges were antialiased. Sharp 
edges in the texture were left alone...these guys apparently didn't use 
textures with sharp edges. ;-)
This technique could be adapted to POV as a way of specifying different 
antialiasing parameters for object edges and textures...if the hash 
value triggers it, use one setting, but if the color difference is 
greater than a threshold (and the hash values are the same), use a 
different setting. If it could be further controlled...certain textures 
or objects using no antialiasing...it could make things like starfields 
much easier.

This reminds me...are the colors clipped before or after antialiasing? 
It should be after...a "superbright" object (rgb > 1) should contribute 
more to a pixel than a dim (rgb 1) one.

-- 
Christopher James Huff <chr### [at] maccom>
POV-Ray TAG e-mail: chr### [at] tagpovrayorg
TAG web site: http://tag.povray.org/

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