[GRASS-user] Euclidean distance (grow.distance) on raster to certain extent?

[Tanya Dyck]

Thank you Moritz, this worked beautifully!

> Date: Mon, 7 May 2012 18:00:01 +0200
> From: mlennert at club.worldonline.be
> To: lee at isi-solutions.org
> CC: tanya.dyck at hotmail.com; grass-user at lists.osgeo.org
> Subject: Re: [GRASS-user] Euclidean distance (grow.distance) on raster to certain extent?
> 
> On 07/05/12 16:36, Daniel Lee wrote:
> > Hi Tanya,
> >
> > I would use r.distance rather than r.grow.distance and then reclassify
> > the results to include only areas with <=1108 m distance - that should
> > be a lot easier.
> 
> I don't think r.distance gives what you want, however r.grow.distance 
> should be exactly your tool:
> 
> As a starting point you need a raster map with all pixels in the orchard 
> non-null and all other pixels null  Let's call that raster map 
> 'orchard'. Then you can do the following:
> 
> r.grow.distance input=orchard distance=distance_map
> 
> Then, if you only want to see the distance from the orchard to 1108m, 
> then you can use r.mapcalc:
> 
> r.mapcalc "final_distance_map=if(distance_map>1108, null(), distance_map)"
> 
> All this keeping in mind that I don't understand what you mean by "I 
> recognize this tool does not allow a distance to be included".
> 
> If this means that you also want to measure a distance _within_ the 
> orchard, then instead of using a raster map of the orchard, use as input 
> to r.grow.distance a raster map with only the center pixel of the 
> orchard non-null.
> 
> Moritz
> 
> >
> > 2012/5/7 Tanya Dyck <tanya.dyck at hotmail.com <mailto:tanya.dyck at hotmail.com>>
> >
> >     Hello,
> >
> >     I am trying to run the grow.distance command to create a raster that
> >     displays the euclidean distance from an 'orchard' outward to 1108m.
> >       I am not trying to measure the distance between 2 non-null
> >     features, but simply wish to have the euclidean distance extend out
> >     from the orchard to 1108m.  I recognize this tool does not allow a
> >     distance to be included so I created a buffer around my orchard
> >     (1108m) and intended to run grow.distance on that, however it
> >     outputs the distance as if it includes the full raster extent (so I
> >     have an output raster of 1108m that is all yellow as opposed to a
> >     range of values displaying varying distances) and not limited to my
> >     buffer. I want it to assume the buffer extent is the raster extent,
> >     so to speak.  Is there another way to do this?
> >     Any ideas would be much appreciated.
> >
> >     Best,
> >
> >     Tanya
> >
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> >
> >
> >
> >
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> 
 		 	   		  
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