.TH r.surf.fractal 1grass "" "GRASS 8.3.2" "GRASS GIS User's Manual"
.SH NAME
\fI\fBr.surf.fractal\fR\fR  \- Creates a fractal surface of a given fractal dimension.
.SH KEYWORDS
raster, surface, fractal
.SH SYNOPSIS
\fBr.surf.fractal\fR
.br
\fBr.surf.fractal \-\-help\fR
.br
\fBr.surf.fractal\fR \fBoutput\fR=\fIname\fR  [\fBdimension\fR=\fIfloat\fR]   [\fBnumber\fR=\fIinteger\fR]   [\-\-\fBoverwrite\fR]  [\-\-\fBhelp\fR]  [\-\-\fBverbose\fR]  [\-\-\fBquiet\fR]  [\-\-\fBui\fR]
.SS Flags:
.IP "\fB\-\-overwrite\fR" 4m
.br
Allow output files to overwrite existing files
.IP "\fB\-\-help\fR" 4m
.br
Print usage summary
.IP "\fB\-\-verbose\fR" 4m
.br
Verbose module output
.IP "\fB\-\-quiet\fR" 4m
.br
Quiet module output
.IP "\fB\-\-ui\fR" 4m
.br
Force launching GUI dialog
.SS Parameters:
.IP "\fBoutput\fR=\fIname\fR \fB[required]\fR" 4m
.br
Name for output raster map
.IP "\fBdimension\fR=\fIfloat\fR" 4m
.br
Fractal dimension of surface (2 < D < 3)
.br
Default: \fI2.05\fR
.IP "\fBnumber\fR=\fIinteger\fR" 4m
.br
Number of intermediate images to produce
.br
Default: \fI0\fR
.SH DESCRIPTION
\fBr.surf.fractal\fR 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).
.PP
This module generates naturally looking synthetical elevation models
(DEM).
.SH NOTE
This module requires the FFTW library
for computing Discrete Fourier Transforms.
.SH EXAMPLE
Generate surface using fractals in selected region, set color table and
display with shade.
.br
.nf
\fC
g.region \-p raster=elevation
r.surf.fractal output=fractals
r.colors map=fractals color=byr
r.relief input=fractals output=fractals_shade
d.mon wx0
d.shade shade=fractals_shade color=fractals b=50
\fR
.fi
.br
Artificial surface created with fractals
.br
Compare results when using different fractal dimensions:
.br
.nf
\fC
# D=2.0005
g.region \-dp
r.surf.fractal out=dem_d2_0005 dim=2.0005
r.info \-r dem_d2_0005
r.mapcalc \(dqdem_d2_0005_final = 1.0 * dem_d2_0005 + abs(min(dem_d2_0005))\(dq
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 \(dqdem_d2_90_final = 1.0 * dem_d2_90 + abs(min(dem_d2_90))\(dq
r.colors dem_d2_90_final color=terrain
r.slope.aspect dem_d2_90_final aspect=dem_d2_90_final_as
\fR
.fi
.br
Artificial DEMs created with fractals:
.br
top: fractal dimension d=2.0005 (left: elevation map, right: aspect map)
.br
top: fractal dimension d=2.90 (left: elevation map, right: aspect map)
.SH REFERENCES
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.
.SH SEE ALSO
\fI
r.surf.contour,
r.surf.idw,
r.surf.gauss,
r.surf.random,
v.surf.idw,
v.surf.rst
\fR
.SH AUTHOR
Jo Wood,
Midlands Regional Research Laboratory (ASSIST),
University of Leicester
.SH SOURCE CODE
.PP
Available at:
r.surf.fractal source code
(history)
.PP
Accessed: Thursday Mar 07 18:15:24 2024
.PP
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.PP
© 2003\-2024
GRASS Development Team,
GRASS GIS 8.3.2 Reference Manual