[GRASSLIST:275] Re: r.proj

[Sean Fulton]

On Sunday 01 June 2003 06:26 am, you wrote:
> On Sun, 1 Jun 2003, Sean Fulton wrote:
> > Hello,
> >
> > I'm trying to project some raster data from Lat/Lon/GRS80/NAD83 to
> > Albers/Clark66/NAD27. The data was downloaded from USGS NED site as
> > GeoTIFFs and imported using r.in.gdal without problems.
> >
> > When trying project the data, r.proj does its thing and appears to work,
> > however the range of data as shown by r.info for the newly projected
> > rasters show a min and max that are the same. On successive attempts the
> > vaules for min and max were 0, nan or -2147483648.
>
> What GRASS version are you using and what information does r.proj output
> to the screen? What is in the PROJ_INFO files (output of g.projinfo
> command). For projection information created by r.in.gdal the datum name
> may be in capitals and may need to be changed to small letters (e.g. NAD83
> to nad83) by manually editing the PROJ_INFO file, depending on which GRASS
> version you are using.
>
> Not really suggestions for solving the problem but the extra information
> might shed more light on it...

Thanks, Paul, that information pushed me in the right direction. I had set up 
the Lat/Lon location manually and imported the maps. I tried importing them 
to a new location using gdal (r.in.gdal in=file out=map location=latlon2) to 
set up the location. Projection from this new location worked! And the datum 
is in upper case. The projected maps look fine (except for color tables but I 
could manually copy those).

I've include the g.projinfo for both Lat/Lon locations in case this is useful 
to anyone (or anyone can explain what I did wrong).

Regards

	Sean

>From the first latlon location (manually set up):
-----------------------------------------------------------
PROJ_INFO file:
name:    Latitude-Longitude
datum:   nad83
dx:      0.000000
dy:      0.000000
dz:      0.000000
proj:    ll
ellps:   grs80
-----------------------------------------------------------
PROJ_UNITS file:
unit:    degree
units:   degrees
meters:  1.0
-----------------------------------------------------------

>From the latlon location (set up by r.in.gdal):
-----------------------------------------------------------
PROJ_INFO file:
proj:    ll
ellps:   grs80
datum:   NAD83
name:    Lat/Lon
a:       6378137
es:      0.0066943800
-----------------------------------------------------------
PROJ_UNITS file:
unit:    degree
units:   degrees
meter:   1.0
-----------------------------------------------------------