Hello, Thanks for your suggestion. The point is that I need do develop a distributed infrastructure hence I need to store the raster in to a DB after the creation. Once I have created the raster immages I'll need to do some simple multiplication and I thought to do them with r.mapcalc. Then I'll use a vector map in order to extract the values of the raster.
So i think I'll have to use inevitably a DBMS to store the raster images produced with grass. I'm I wright? Tnx again regards Lorenzo 2015-10-08 8:40 GMT+02:00 Blumentrath, Stefan <[email protected]>: > Hi Dylan, > > > > Yes, r.external and r.external.out works pretty well with TGIS. Here is a > discussion in this regards I had mainly with Sören… > > https://lists.osgeo.org/pipermail/grass-user/2013-December/069377.html > > > > I have used r.external/r.external.out in TGIS for a while (with compressed > GeoTiffs, btw you should not pre-define the predictor for LZW-compression > as long as you are not sure that all raster maps are of the same type > (CELL/FCELL/DCELL)), but went back to using internal GRASS format, because > external links are a bit tricky to use on NFS and from different OS (or if > data is moved): > > https://trac.osgeo.org/grass/ticket/2660 > > > > Another minor (and often neglectable) drawback of using r.external is that > file names and map names get out of sync if you rename maps. g.rename > renames only the GRASS internal map name (modifies the link) the underlying > data file is not touched and stays with the old name… > > > > Cheers > > Stefan > > > > > > *From:* Dylan Beaudette [mailto:[email protected]] > *Sent:* 8. oktober 2015 00:17 > *To:* Markus Neteler <[email protected]> > *Cc:* Blumentrath, Stefan <[email protected]>; GRASS user list < > [email protected]> > *Subject:* Re: [GRASS-user] External Database and projections > > > > The use of r.external makes a lot of sense when dealing with very large > files. Does the use of "external" files work as expected in all of the new > t.* modules? > > > > Thanks, > > Dylan > > > > On Wed, Oct 7, 2015 at 12:09 PM, Markus Neteler <[email protected]> wrote: > > On Wed, Oct 7, 2015 at 12:55 PM, Blumentrath, Stefan > <[email protected]> wrote: > ... > > My suggestion is to not use PostGIS for big rasters, unless you have to, > > because you want to use the data in a specific application for example. > > Note r.external and r.external.out of GRASS GIS 7 for avoiding data > duplication: > > https://grass.osgeo.org/grass70/manuals/r.external.html > https://grass.osgeo.org/grass70/manuals/r.external.out.html > > Here an example: > > # register (rather than import) a GeoTIFF file in GRASS GIS: > r.external input=terra_lst1km20030314.LST_Day.tif output=modis_celsius > > # define output directory for files resulting from subsequent calculations: > r.external.out directory=$HOME/gisoutput/ format="GTiff" > > # perform calculations (here: extract pixels > 20 deg C) > # store output directly as GeoTIFF file, hence add the .tif extension: > r.mapcalc "warm.tif = if(modis_celsius > 20.0, modis_celsius, null() )" > > # cease GDAL output connection and turn back to write standard GRASS > raster files: > r.external.out -r > > # use the result elsewhere > qgis $HOME/gisoutput/warm.tif > > Best > Markus > _______________________________________________ > grass-user mailing list > [email protected] > http://lists.osgeo.org/mailman/listinfo/grass-user > > > > _______________________________________________ > grass-user mailing list > [email protected] > http://lists.osgeo.org/mailman/listinfo/grass-user >
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