I find I'm dipping into GRASS programming, unless someone has already
done what I'm wanting to do. I have two questions:
1. I am wanting to write a GRASS routine to create a raster layer of
"Landform Elements" as in D.J.Pennock, Zebarth and DeJong, 1987,
Geoderma 40:297-315. The Landscape Elements are calculated from
an elevation raster layer, based on gradient, profile (downslope)
curviture, and plan (across-slope) curviture.
Please, please, please, someone tell me the routine I want (or
at least parts of it) is already available. 
2. How shall I deal with the "integer only" limitation of GRASS raster
files? For the elevation input data, if it is in units of meters,
and the cells are close to 1m x 1m in dimensions, the equations won't
work very well, for anything but very hilly landscapes. Do I specify
that the input file must be in elevation units of cm? Or test that
the units of elevation are an order of magnitude finer than the cell
dimensions? And for the output files, I would like to be able to make
raster surfaces of the aspect, gradient, profile curviture and plan
curviture as well as the landform elements, but some of these are
fractional values. I suppose I can output (value x 100) or some
such.
Yours looking for ideas,
Tim.
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Tim Martin * Reluctant to find he's
Spatial Information Systems * stuck in the nineties
University of Alberta * again.
martin@ulysses.sis.ualberta.ca * - Moxy Fruvous
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