[Qgis-user] projection confused during import from Grass to QGIS

Tyler Smith tyler at plantarum.ca
Mon May 11 14:11:13 PDT 2015


Hi,

I'm exporting some data from Grass 6.4 to QGis as .asc files. The source
location in Grass has the projection:

g.proj -p
-PROJ_INFO-------------------------------------------------
name       : Lat/Lon
proj       : ll
datum      : wgs84
ellps      : wgs84
no_defs    : defined
-PROJ_UNITS------------------------------------------------
unit       : degree
units      : degrees
meters     : 1.0

I generated the asc file from Grass with:

r.out.ascii input=tri_median at PERMANENT output=tri_median.asc 

When I import this into QGis, the layer is flipped east to west - the
atlantic coast of NA appears on the west, rather than the east!

The header appears correct:

tws:~$ head -6 tri_mean.asc 
north: 46:53:04.633938N
south: 34:44:13.536462N
east: 68:50:28.1616W
west: 94:51:40.938811W
rows: 1458
cols: 3122

But gdal mis-reads it:

tws:~$ gdalinfo tri_mean.asc 
Driver: GRASSASCIIGrid/GRASS ASCII Grid
Files: tri_mean.asc
Size is 3122, 1458
Coordinate System is `'
Origin = (94.000000000000000,46.000000000000000)
Pixel Size = (-0.008327994875080,-0.008230452674897)
Corner Coordinates:
Upper Left  (  94.0000000,  46.0000000) 
Lower Left  (  94.0000000,  34.0000000) 
Upper Right (  68.0000000,  46.0000000) 
Lower Right (  68.0000000,  34.0000000) 
Center      (  81.0000000,  40.0000000) 
Band 1 Block=3122x1 Type=Float32, ColorInterp=Undefined

I also tried opening this map directly from Grass within QGIS using the
Grass plugin. The problem persists - the projection of the map is
flipped east to west when it appears in QGIS.

Have I done something wrong somewhere, or is there a problem with the
Grass 6.4 export or QGis/gdal import?

Thanks!

-- 
  Tyler Smith
  plantarum.ca



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