[GRASS-user] Re: r.grow: Manual Page Needs Additional Information

[Moritz Lennert]

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