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Science Forum Index » Fractals Science Forum » PSD, two dimensional
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| Wayne |
 Posted: Fri Feb 29, 2008 1:49 pm |
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Does anyone know of any work fitting functions to 2D fractal PSDs
where the original surface was not isotropic??
Thanks |
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| Roger Bagula |
| Posted: Thu Mar 06, 2008 12:21 pm |
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Wayne wrote:
Quote: Does anyone know of any work fitting functions to 2D fractal PSDs
where the original surface was not isotropic??
Thanks
Wayne,
Sending in posts with obscure references unexplained...
http://ieeexplore.ieee.org/Xplore/login.jsp?url=/iel5/79/22084/01028352.pdf?tp=&isnumber=&arnumber=1028352
Quote: *Stochastic fractal models for image processing*
Pesquet-Popescu, B.; Vehel, J.L.
Signal Processing Magazine, IEEE
Volume 19, Issue 5, Sep 2002 Page(s): 48 - 62
Digital Object Identifier 10.1109/MSP.2002.1028352
*Summary:* Our study of fractal landscapes departs from the simplest
but yet effective model of fractional Brownian motion and explores its
two-dimensional (2-D) extensions. We focus on the ability to introduce
_/*anisotropy*/_ in this model, and we are also interested in
considering its discrete-space counterparts. We then move towards
other multifractional and multifractal models providing more degrees
of freedom for fitting complex 2-D fields. We note that many of the
models and processing are implemented in FracLab, a software
MATLAB/Scilab toolbox for fractal processing of signals and images. |
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| Wayne |
| Posted: Mon Mar 10, 2008 7:26 am |
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On Mar 6, 9:21 am, Roger Bagula <rlbag...@sbcglobal.net> wrote:
Quote: Wayne wrote:
Does anyone know of any work fitting functions to 2D fractal PSDs
where the original surface was not isotropic??
Thanks
Wayne,
Sending in posts with obscure references unexplained...
Thanks for the very interesting reference.
PSD = power spectral density which is just the 2D Fourier transform of
the surface height sampled on an x y grid. I do not consider this
concept obscure at all.
Isotropic just means the same in all directions.
If an optical surface is not polished completely the same in all
directions of stroke, then the 2D PSD will not be isotropic.
In other words it will not be describable by a one dimensional fractal
line which is rotated around the intensity axis to make a cone shape
in 3 dimensions.
Strictly speaking, fractals in frequency space are one dimensional,
and there is not a lot of work on 2 dimensional plots that are not
simple extensions
of the one dimensional fractal.
Wayne |
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