[GRASS-user] r.patch for stitching rasters?

[Boris Avdeev]

Well, you assuming that NULL=0, but the sole reason for having NULL
layer in grass is that those values are not identical.

Boris

On Nov 16, 2007 5:55 PM, Charles Ehlschlaeger
<c.ehlschlaeger at insightbb.com> wrote:
> > I couldn't figure out how to make gdal_merge output NULLs
> > instead of 0s (and what formats support NULLs?).
>
> r.mapcalc can easily convert your 0s into NULLS with the expression:
>
> newmap = if(map == 0, null(), map)
>
> r.mapcalc will solve most raster problems. GRASS users are advised to know
> that program inside and out.
>
> Sincerely, chuck
>
> Chuck Ehlschlaeger, Associate Professor of Geography
> Western  Illinois  University
> 215 Tillman Hall, 1 University Circle, Macomb, IL 61455
> cre111 at wiu.edu, phone: 309-298-1841, fax: 309-298-3003
>
>
> -----Original Message-----
> From: grass-user-bounces at lists.osgeo.org
> [mailto:grass-user-bounces at lists.osgeo.org] On Behalf Of Boris Avdeev
> Sent: Friday, November 16, 2007 1:11 PM
> To: dylan.beaudette at gmail.com
> Cc: grass-user at lists.osgeo.org
> Subject: Re: [GRASS-user] r.patch for stitching rasters?
>
> Yes, though I couldn't figure out how to make gdal_merge output NULLs
> instead of 0s (and what formats support NULLs?).
> But anyway, you think that this is normal performance?
>
> On Nov 16, 2007 2:08 PM, Dylan Beaudette <dylan.beaudette at gmail.com> wrote:
> > On Friday 16 November 2007, Boris Avdeev wrote:
> >
> > > Now, when you asking...
> > > Now it is this:
> > >
> > > projection: 3 (Latitude-Longitude)
> > > zone:       0
> > > datum:      wgs84
> > > ellipsoid:  wgs84
> > > north:      48:50:24.701676N
> > > south:      34:38:56.353164N
> > > west:       45:57:00.735336E
> > > east:       55:00:56.276712E
> > > nsres:      0:01:00.033312
> > > ewres:      0:00:59.991804
> > > rows:       851
> > > cols:       544
> > > cells:      462944
> > >
> > > But I believe that at the time I started r.patch it was this:
> > >
> > > projection: 3 (Latitude-Longitude)
> > > zone:       0
> > > datum:      wgs84
> > > ellipsoid:  wgs84
> > > north:      46N
> > > south:      35N
> > > west:       35E
> > > east:       55E
> > > nsres:      0:00:03
> > > ewres:      0:00:03
> > > rows:       13200
> > > cols:       24000
> > > cells:      316800000
> > >
> > > since I was trying to preserve resolution of original srtms.
> > >
> > > Boris
> > >
> >
> > That is pretty big, but not impossibly big. Have you considered something
> like
> > gdal_merge.py for merging the files outside of GRASS ?
> >
> > cheers,
> >
> > Dylan
> >
> >
> > >
> > > PS Sorry Dylan
> > >
> > > On Nov 16, 2007 12:49 PM, Dylan Beaudette <dylan.beaudette at gmail.com>
> wrote:
> > > > On Friday 16 November 2007, Boris Avdeev wrote:
> > > > > Hello grass (ab)users!
> > > > > I am using r.patch to merge 200 1 degree, 3 seconds resolution
> srtm's
> > > > > (1-2 Mb each). After 24 hours of real time and 20 hours of Xeon
> > > > > processor time I have 39% completed! My guess that this task
> shouldn't
> > > > > take so long. Is r.patch a wrong tool to do this thing? Or is it a
> > > > > bug? I am using grass-6.3.cvs.
> > > > >
> > > > > Thanks,
> > > > > Boris
> > > >
> > > > check region extents and resolution ... can you send the output from
> > > > g.region -p ?
> > > >
> > > > Dylan
> > > >
> > > >
> > > > --
> > > > Dylan Beaudette
> > > > Soil Resource Laboratory
> > > > http://casoilresource.lawr.ucdavis.edu/
> > > > University of California at Davis
> > > > 530.754.7341
> >
> >
> >
> > --
> >
> > Dylan Beaudette
> > Soil Resource Laboratory
> > http://casoilresource.lawr.ucdavis.edu/
> > University of California at Davis
> > 530.754.7341
> >
> _______________________________________________
> grass-user mailing list
> grass-user at lists.osgeo.org
> http://lists.osgeo.org/mailman/listinfo/grass-user
>
> No virus found in this incoming message.
> Checked by AVG Free Edition.
> Version: 7.5.503 / Virus Database: 269.15.33/1133 - Release Date: 11/15/2007
> 8:57 PM
>
>
> No virus found in this outgoing message.
> Checked by AVG Free Edition.
> Version: 7.5.503 / Virus Database: 269.15.33/1133 - Release Date: 11/15/2007
> 8:57 PM
>
>