In article <3d53af5d$1@news.povray.org>, "Mael" <mae### [at] hotmailcom> 
wrote:

> >   Has anyone fixed or is planning on fixing the grid in noise artifact?
> 
> May be this paper can help :
> http://mrl.nyu.edu/perlin/paper445.pdf
> 
> "The original algorithm, although efficient, suffered from two defects: second
> order discontinuity across coordinate-aligned integer boundaries, and a
> needlessly expensive and somewhat problematic method of computing the
> gradient. We (belatedly) remove these defects."

The POV Team knows about this paper. However, I don't think it removes 
all the grid artifacts, it just uses a different spline interpolation 
that fixes the second derivative discontinuities and has another fix 
that makes the noise a little more even, with less "clumping".

-- 
Christopher James Huff <cja### [at] earthlinknet>
http://home.earthlink.net/~cjameshuff/
POV-Ray TAG: chr### [at] tagpovrayorg
http://tag.povray.org/

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