About r.surf.fractal

[Terry Duell]

Venkatesh Raghavan wrote:
> 
> Hi,
> Jacques Bouchard wrote:
> 
> > BTW, what is the use of r.surf.fractal ?
> >
> I am developing a program to calculate fractal dimension of topographic
> surfaces using DEM. I hope to check if is working okay using the
> synthetic fractal surfaces generated by r.surf.fractal.
> 
---------snip-----------
We have been working on an application to calculate the fractal dimensions of
a surface (further development of an approach developed by Lawrence Martin at
the US Army materiel Systems Analysis Activity).
If the fractal dimension of a surface is known, one can use it to interpolate
within a low resolution data set to generate a surface with higher resolution
and appropriate properties (which one doesn't get by linear interpolation).
This can be much more time and $ cost effective (for some purposes) than
developing a 'true' higher resolution DEM.
The approach adopted to establish the fractal dimension is based on the
surface area to plan area of each 'cell' in a regular raster array, and
calculating this for a number of resolutions of the sample data (ie at
original resolution, then discard every second point etc).
Tests thus far have promising results in fractal interpolation of DEM, but it
must be added that quite a bit more testing is required.
The theoretical aspects can be overshadowed by a poor choice of boundaries on
the sample data (ie the sample data really contains a number of different
'roughness' surfaces which should be treated separately and not ascribed the
same fractal number).
Cheers,
-- 
Terry Duell, Senior Mobility Engineer
Army Technology & Engineering Agency                   
Maribyrnong, Victoria, Australia
ph:61-3-93195837 fax:61-3-93195830