[GRASS-user] r.lake units

Maris Nartiss maris.gis at gmail.com
Wed Aug 8 02:28:23 EDT 2007


thanks for good words :) That blue gradient took some time till it
looked good :) If I will have time, I will look how to add it to
default GRASS gradients, as currently it is hardcoded into r.lake code

Talking about units - warning about volume is a bit incorrect, but now
I have no time to seek proper solution. Volume calculation in r.lake
is done by taking cell size (G_area_of_cell_at_row(row)) * cell count
* cell depth. As You may see - it will work only if depth is in same
units as cell size. There was some movement to add raster metadata
about it's units, but as I'm still in summer regime, I have no time to
investigate how to use it to make volume calculations allways correct
(i.e. if area is in m but depth (elevation) is in feet or any other
strange unit). I will put this issue on my (long) to-do list (nearby
wish to have 3D raster output).
r.lake reported area will be in units returned by
G_area_of_cell_at_row(row). IIRC they where meters. This also could be
changed to user's preferred units.
Anyway - You can always use other tools for area/volume calculations
(r.stats,r.mapcalc) etc.

If You have more questions - feel free to ask.


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