In article <web.3f4d28bf8f004971d63a77300@news.povray.org> , 
"gramirosimancas" <nomail@nomail> wrote:

>>To the contrary, you only end up with extremely difficult intersection
>>algorithms and still have to use some kind of averaging over the surfaces
>>you find as they have textures.
>
> That's the point in using pyramid tracing: "the averaging over the surfaces
> even with textures". I thought you know what is was talking about.

How do you create an average over a sample area you cannot determine?  If
you cannot get the surface area, you cannot compute an average.  And even if
you can get the surface area, you cannot compute the average color for all
kinds of textures because many of the textures used in POV-Ray have
properties similar to fractals.  Not to mention the fractal patterns...

> No current antialias method in povray can cope with a simple checker surface
> at any distance while using pyramid raytracing have always best results at
> any distance. If you use a checker structure with a program that uses
> libart you'll see there's no energy lost at any distance (i.e. the picture
> is neither completely black nor completely white.

No, they can deal with it very well.  If you take 256 or more samples per
pixel (using method 1), you will get a correct result for a eight bits per
color component image at the horizon.  That is, if the surface pattern is
exactly white and exactly black within the sampled pixel, you will get a 50%
gray pixel result.

Or in short, there is an upper bound for the number of samples you need to
take for any color space resolution in case of the checker pattern.

    Thorsten

____________________________________________________
Thorsten Froehlich, Duisburg, Germany
e-mail: tho### [at] trfde

Visit POV-Ray on the web: http://mac.povray.org

Post a reply to this message