[GRASS-user] Wrong projection info after importing Geotif

[Markus Neteler]

On Wed, Oct 22, 2008 at 10:34 AM, Agustin Lobo <aloboaleu at gmail.com> wrote:
> Hi!
>
> I'm trying to import a geotif file
> (http://user.uni-frankfurt.de/~grieser/downloads/NetPrimaryProduction/npp_CruP_All_fine_geo.zip)

Note that the map exceeds South!


gdalinfo npp_CruP_All_fine_geo.tif
Driver: GTiff/GeoTIFF
Files: npp_CruP_All_fine_geo.tif
Size is 4320, 2160
Coordinate System is:
GEOGCS["WGS 84",
 ...
Metadata:
  AREA_OR_POINT=Area
...
Pixel Size = (0.083333333343262,-0.083333333343262)
...
Corner Coordinates:
Upper Left  (-179.9583334,  89.9583333) (179d57'30.00"W, 89d57'30.00"N)
Lower Left  (-179.9583334, -90.0416667) (179d57'30.00"W, 90d 2'30.00"S)
Upper Right ( 180.0416667,  89.9583333) (180d 2'30.00"E, 89d57'30.00"N)
Lower Right ( 180.0416667, -90.0416667) (180d 2'30.00"E, 90d 2'30.00"S)
Center      (   0.0416667,  -0.0416667) (  0d 2'30.00"E,  0d 2'30.00"S)
Band 1 Block=4320x1 Type=Byte, ColorInterp=Gray
  NoData Value=254
  Offset: 0,   Scale:10.4598910148779

-> 90d 2'30.00"S does not quite exist.

Looking at North:
> 89.9583333+0.083333333343262
[1] 90.04167

I suspect a pixel-refers-to-center versus pixel-refers-to-corner bug in the
map.

> I import the geotif file with:
>  r.in.gdal input=/media/mifat32/MASTER_ICTA2007_2008/2008b/npp.tif
> output=npp

Here I get

GRASS 6.4.svn (latlong):~ > r.in.gdal npp_CruP_All_fine_geo.tif out=test
Projection of input dataset and current location appear to match
WARNING: Fixing subtle input data rounding error of south boundary
         (-0.0416667>4.62963e-07)
 100%
<test> created
r.in.gdal complete.

-> South is "fixed" (not necessarily correct, though, see above).

GRASS 6.4.svn (latlong_tbe_climate):~ > g.region rast=test -p
projection: 3 (Latitude-Longitude)
zone:       0
datum:      wgs84
ellipsoid:  wgs84
north:      89:57:30.000039N
south:      90S
west:       179:57:30.000077W
east:       179:57:29.999923W
nsres:      0:05:00.069477
ewres:      0
rows:       2159
cols:       4320
cells:      9326880

-> Global wrap around problem... due to the apparently shifted map:
179d57'30.00"W and 180d 2'30.00"E do not look right to me.


> But, according to gdalinfo, the geotif file is correct:
>
> $ gdalinfo npp.tif
> Driver: GTiff/GeoTIFF
> Files: npp.tif
> Size is 1440, 572
...

You are looking at a different file here, comparing the size and the
coordinates.

The map in the ZIP file doesn't look properly positioned to me.
Subsequently GRASS fails.

Markus