Glynn, Wolf,
Sorry to take so long to respond -- both of your solutions are just
what I needed.
Thank you very much.
-Don
At 3:00 AM +0000 3/9/10, Glynn Clements wrote:
Don MacQueen wrote:
I'm pretty new to GRASS, and would appreciate some
help/guidance/suggestions:
I have been smoothing a raster with r.neighbor, as in this example:
r.neighbors input=aland...@permanent output=alandcov_smooth
method=mode size=45 {title=Smoothed}
The raster values are integers representing qualitative categories.
I'd like to modify the smoothing to exclude a particular value.
Specifically, if a cell (is that the right term?) has a particular
value, say 11, then I want to exclude it, as follows:
- if the center of the neighborhood = 11, leave it unchanged (do
not calculate the mode, just return 11)
- if the center is not 11, calculate the mode, but exclude any
points in the neighborhood whose value = 11 (that is, take the mode
only of points not equal to 11)
The real goal is to preserve boundaries between 11 and not 11. This
is a land cover raster; 11 represents water, and I would like the
smoothing to not change water to land or vice versa.
It seems like it might be possible to do it by creating a mask,
smoothing the masked raster, and then putting the 11's back in maybe
using r.mapcalc, but the details are a bit tough for me to put
together, as a GRASS newbie.
r.mapcalc 'elevens = if(alandcov == 11,11,null()) ; others =
if(alandcov == 11,null(),alandcov)'
r.neighbors input=others output=alandcov_tmp method=mode size=45
r.mapcalc 'alandcov_smooth = if(not(isnull(elevens)),elevens,alandcov_tmp)'
g.remove rast=elevens,others,alandcov_tmp
--
Glynn Clements <[email protected]>
At 8:08 AM +0200 3/9/10, Wolf Bergenheim wrote:
On Tue, Mar 9, 2010 at 02:30, Don MacQueen <[email protected]> wrote:
The real goal is to preserve boundaries between 11 and not 11. This is a
land cover raster; 11 represents water, and I would like the smoothing to
not change water to land or vice versa.
It seems like it might be possible to do it by creating a mask, smoothing
the masked raster, and then putting the 11's back in maybe using r.mapcalc,
but the details are a bit tough for me to put together, as a GRASS newbie.
To create the mask you can use
r.mapcalc 'MASK=if(landcov==11,1,null())
Then after you are done with whatever work you want to do, you can do
this to put the water back like this
r.mapcalc 'final=if(isnull(result)),11,result)'
Hope this helps,
Wolf
--
<8 )---- Wolf Bergenheim ----( 3>
--
--------------------------------------
Don MacQueen
Environmental Protection Department
Lawrence Livermore National Laboratory
Livermore, CA, USA
925-423-1062
--------------------------------------
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