NAME

       r.surf.fractal  - Creates a fractal surface of a given fractal dimension.

KEYWORDS

       raster, DEM, fractal

SYNOPSIS

       r.surf.fractal
       r.surf.fractal help
       r.surf.fractal    output=name     [dimension=float]     [number=integer]     [--overwrite]
       [--verbose]  [--quiet]

   Flags:
       --overwrite
           Allow output files to overwrite existing files

       --verbose
           Verbose module output

       --quiet
           Quiet module output

   Parameters:
       output=name
           Name for output raster map

       dimension=float
           Fractal dimension of surface (2 < D < 3)
           Default: 2.05

       number=integer
           Number of intermediate images to produce
           Default: 0

DESCRIPTION

       r.surf.fractal creates a fractal surface  of  a  given  fractal  dimension.  It  uses  the
       spectral  synthesis method. The module can create intermediate layers showing the build up
       of different spectral coefficients (see Saupe, pp.106-107 for an example of this).

       Use this module to generate naturally looking synthetical elevation models (DEM).

NOTE

       This module requires the FFTW library for computing Discrete Fourier Transforms.

EXAMPLE

       # D=2.0005
       g.region -dp
       r.surf.fractal out=dem_d2_0005 dim=2.0005
       r.info -r dem_d2_0005
       r.mapcalc "dem_d2_0005_final = 1.0 * dem_d2_0005 + abs(min(dem_d2_0005))"
       r.colors dem_d2_0005_final color=terrain
       r.slope.aspect dem_d2_0005_final aspect=dem_d2_0005_final_as
       # D=2.90
       r.surf.fractal out=dem_d2_90 dim=2.90
       r.info -r dem_d2_90
       r.mapcalc "dem_d2_90_final = 1.0 * dem_d2_90 + abs(min(dem_d2_90))"
       r.colors dem_d2_90_final color=terrain
       r.slope.aspect dem_d2_90_final aspect=dem_d2_90_final_as
       d.mon x0
       d.erase -f
       d.split.frame
       d.frame -s uno
       d.rast dem_d2_0005_final
       d.frame -s dos
       d.rast dem_d2_0005_final_as
       d.frame -s tres
       d.rast dem_d2_90_final
       d.frame -s cuatro
       d.rast dem_d2_90_final_as
        Artificial DEMs created with fractals:
       top: fractal dimension d=2.0005 (left: elevation map, right: aspect map)
       top: fractal dimension d=2.90 (left: elevation map, right: aspect map)

REFERENCE

       Saupe, D. (1988) Algorithms for random fractals, in Barnsley M.,  Devaney  R.,  Mandelbrot
       B.,  Peitgen,  H-O.,  Saupe  D., and Voss R.  (1988) The Science of Fractal Images, Ch. 2,
       pp.71-136. London: Springer-Verlag.

SEE ALSO

       r.surf.contour,  r.surf.idw,   r.surf.gauss,   r.surf.random,   r.surf.idw2,   v.surf.idw,
       v.surf.rst

AUTHOR

       Jo Wood, Midlands Regional Research Laboratory (ASSIST), University of Leicester

       Last changed: $Date: 2012-11-26 16:18:53 -0800 (Mon, 26 Nov 2012) $

       Full index

       © 2003-2013 GRASS Development Team