[GRASS-user] Can I use r.mapcalc to create "sorted" elevation raster?

[Greg Corning]

Thank you all. Happy New Year!

On Sun, Dec 26, 2010 at 3:50 AM, Micha Silver <micha at arava.co.il> wrote:
> Three equivalent answers in as many minutes. Talk about good service ;-)
>
> On 26/12/2010 13:10, Malte Martin wrote:
>
> Hi
> should be something like (untested)
> r.mapcalc 'elevation300map=if((originalelevationmap >
> 300),originalelevationmap,NULL())'
> this means:
> if originalelevationmap > 300 get the value from the originalelevationmap,
> otherwise the value should be NULL and all is wirtten to the map
> elevation300map.
> Otherwise take a closer look to
> http://grass.osgeo.org/gdp/html_grass64/r.mapcalc.html
> I haven't used r.mapcalc for a long time so I don't know if there had been
> changes in the syntax - the trick is to use the if clause implemented in
> r.mapcalc. I have no QGIS/GRASS installed on this pc...
> I hope that helps and merry christmas
> Malte
>
> Am 26.12.2010 um 11:51 schrieb Catlike:
>
> Thank you for reading.
> I am trying to use r.mapcalc, through QGIS, to take an elevations raster
> with a wide variety of values and create a new elevations raster which only
> contains those cells that have a value over a certain number (in this case,
> 300 meters).
> Unfortunately, the QGIS graphic user interface does not show me what the
> actual command I create is.
> What I get when I run the command is a new raster in which every cell has
> been converted to equal 300 meters!
> What should I do differently?
> Again, thank you.
> --
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> Malte Martin
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> --
> Micha Silver
> http://www.surfaces.co.il/
> Arava Development Co.  +972-52-3665918
>