On Tue, Feb 24, 2015 at 6:19 AM, Paolo Cavallini <[email protected]> wrote:
> > -------- Messaggio Inoltrato -------- > > Oggetto: Re: [Qgis-developer] QGIS and GRASS 7.0.0 > > Data: Tue, 24 Feb 2015 08:08:18 +0100 > > Mittente: Paolo Cavallini <[email protected]> > > Organizzazione: Faunalia > > A: Pedro Venâncio <[email protected]> > > CC: qgis-developer <[email protected]> > > > > Olá Pedro, > > > > Il 23/02/2015 22:06, Pedro Venâncio ha scritto: > > > >> Despite the great advantages of GRASS commands in Processing, I think > >> that the GRASS plugin still plays an important role and is an excellent > >> interface for GRASS. For those who still like to use the paradigm of > >> locations, mapsets and the GRASS topological model, GRASS plugin is very > >> important, because then it allows to use all QGIS tools, for example, to > >> create layouts using the Composer, etc. > > > > Agreed. Moreover, the overhead of importing/exporting data for each step > > of a complex analysis puts GRASS algs to a disadvantage for Processing > > users. > > The overhead is not necessarily needed in case of raster maps: > > #### Workflow example: > # register GeoTIFF file in GRASS GIS database (no import but direct link): > r.external input=tempmap1.tif output=modis_celsius > > # define output directory for files resulting from GRASS calculation: > # i.e. GRASS GIS writes directly a GeoTIFF file here, no GRASS DB storage > r.external.out directory=$HOME/gisoutput/ format="GTiff" > > # perform calculation (here: extract pixels > 20 deg C) and > # write output directly as GeoTIFF: > r.mapcalc "warm.tif = if(modis_celsius > 20.0, modis_celsius, null() )" > > # cease GDAL output connection and turn back to write GRASS raster files: > r.external.out -r > > # use the result elsewhere > qgis $HOME/gisoutput/warm.tif > #### END Workflow example: > > This approach could be used in "Processing" as well. Or in a WPS context > etc. > Hi, see also GRASS GIS (+QGIS?) GSoC 2015 idea for further discussion on that topic: http://trac.osgeo.org/grass/wiki/GSoC/2015#Neweasy-to-usecommandlineinterfaceforGRASSGIS >From the QGIS Processing source code, I actually got an impression that this approach is already used for rasters. Vaclav
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