[GRASS-user] Making fake dem's

[Hamish]

Roger Mason wrote:

> > why not takeing real DEMs? The SRTM dataset is for free and can be
> > used  with grass.
> 
> Because I want to make specific landscape shapes.  It would be an
> immense labour to search the archive of DEM's to find what I want.

Another idea is to use r.mapcalc to make a gaussian bell etc.

> > take a look at r.surf.fractal which is creating synthetic DEMs
> > for you.
> 
> I have GRASS installed on two machines.  r.surf.fractal worked fine on
> my machine at home (6.2.1) but does not exist on my work machine (also
> 6.2.1).  In both cases GRASS was installed from source.  Can you tell
> me what libraries r.surf.fractal depends on so I can figure out how to
> re-configure and re-build?

GRASS needs to be built with FFTW support for r.surf.fractal to work.
Note about that just added to the help page.


dev:
I notice frac.h still defines prototypes for some fns which are now taken
from the fftw lib, and does not #include any fftw headers, or even
<grass/gmath.h>. ??

CVS log of switch to FFTW:
 http://freegis.org/cgi-bin/viewcvs.cgi/grass/src/raster/r.surf.fractal/Attic/fft.c


Hamish