On 27/04/12 15:24, Rich Shepard wrote:
On Fri, 27 Apr 2012, Hermann Peifer wrote:
I am not sure if there is a single answer to when and why one should use
r.grow. I use it before generating area statistics with r.stats, e.g.:
r.stats -c admin_units,land_cover > outfile
Administrative boundaries are usually only defined on land, they do not
cover areas which in the land cover map appear as coastal lagoons, tidal
flats, and similar. So I grow the admin_units map sufficiently, before
running r.stats.
Hermann,
Single answers not required. :-)
Your use is a valid example of when and why r.grow should be applied. A
collection of such examples (on the wiki with references from the manual
page?) would be highly valuable for everyone.
Another example I've come across in an exercice for students: they have
to "build" a dam and then use r.lake to see which area is filled. They
build the dam by drawing a vector line with v.digit, then transforming
it to raster with v.to.rast and adding it to the DEM with r.mapcalc. But
since a single vector line is only one pixel wide, water often gets
through the dam it is a diagonal line. r.grow'ing the line by a few
pixels helps "consolidate" the dam instead of flooding the entire
South-West Wake county ;-)
Moritz
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