[GRASS-user] what is requried when import data to grass?

maven apache apachemaven0 at gmail.com
Thu Jun 11 05:40:39 EDT 2009

Hi Nikos:Thanks for your detailed reply!
And I know the reason of the problem now.
However as what you said,I should create a new location and mapset
if necessary,it does not work.
I create two folders nLocation/nmapset and create a wind file in the nmapset
dir,however when I run the grass gui,I also can not seclect the new location
to enter. It throw the error message:the selection location [nlocation ]is
not valide. Is the procedure I create the new location is wrong? I followed
the maual


2009/6/11 Nikos Alexandris <nikos.alexandris at felis.uni-freiburg.de>

> maven apache:
> > When import some raster data to grass,I use the following cmd:
> > 1) g.region -d
> This sets to the "default" region which one previously needs to define,
> i.e. needs to create with "g.region -s". Please check the manual of
> g.region.
> > 2) r.in.gdal input=D:/test.TIF output=testTT --overwrite
> > I got the error message as following:
> > ---------------
> > Projection of dataset does not appear to match current location.
> >Location PROJ_INFO is:
> >name: UTM
> >datum: nad27
> [...]
> > Import dataset PROJ_INFO is:
> > cellhd.proj = 0 (unreferenced/unknown)
> > ------------------------
> That's seems normal. Your test.TIF either isn't georeferenced or it lost
> its geotags at some point (after editing with non-GIS tool perhaps?).
> > 3) change the cmd to " r.in.gdal -o input=D:/test.TIF output=testTT
> > --overwrite "  I know this override the projection,however I am not
> > sure the potential  effect to the data.
> You should use that only if you _know_ that your test.TIF data are
> projected in the system that your grass-location is defined (e.g.
> "datum: nad27" as one can see in the error message above). If your data
> (test.TIF) are projected in another proj. system expect errors.
> > Now the tiff is imported,and I got testTT.bule testTT.red
> > testTT.green, then I  open them can only see blank. So I wonder it is
> > caused by the projection or location,I use the spanish data as the
> > default location , and I tried to create new location and mapset but
> > never success...
> So, given that test.TIF is in "UTM, datum: nad27" then you need to:
> 1. import with r.in.gdal -o (as you already did).
> 2. g.region rast=testTT.blue
> 3. view your data
> If the test.TIF data are projected in another system you need to:
> 1. find out which is that projection system
> 2. use some gdal tools to assign the proj. information in the test.TIF
> file
> 3. define a "new" grass-location based on the projection information of
> the test.TIF data
> 4. import with r.in.gdal (without the use of "-o" flag)
> 5. g.region rast=OneOfTheImportedBands
> 6. view, process, etc.
> Greetings, Nikos
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