[GRASS-user] Problem with g.region in lat-lon projection

John A Stevenson john.stevenson at ed.ac.uk
Mon Nov 28 07:23:45 EST 2011


I am trying to set up a grid with a specified resolution using 
g.region.  The information about the grid that came with the data that I 
want to plot is:
  X grid origin:                0.2812500
  Y grid origin:                -89.81250
  X grid size:                         640
  Y grid size:                         480
  X grid resolution:            0.5625000
  Y grid resolution:            0.3750000

I set up the grid with the following command:

GRASS 6.4.1 (global_ll_wgs84):~/NAME/G2011 > g.region w=0.2812500 
s=-89.81250 cols=640 rows=480 ewres=0.562500 nsres=0.3750000

I would expect this grid to cover the whole globe (e.g. 640*0.5625=360), 
but instead it just generates a thin strip, and the ewres is too small.

GRASS 6.4.1 (global_ll_wgs84):~/NAME/G2011 > g.region -p
projection: 3 (Latitude-Longitude)
zone:       0
datum:      wgs84
ellipsoid:  wgs84
north:      74N
south:      89:48:45S
west:       0:16:52.5E
east:       24E
nsres:      0:20:28.59375
ewres:      0:02:13.417969
rows:       480
cols:       640
cells:      307200

Where am I going wrong?


Dr John A Stevenson
RSE/Scottish Government Personal Research Fellow
(co-funded by Marie Curie Actions)
School of GeoSciences
The University of Edinburgh
Grant Institute
West Mains Road
Edinburgh EH9 3JW
PHONE: (+44) 131 650 7526
FAX:   (+44) 131 668 3184
email: john.stevenson at ed.ac.uk
web: http://www.geos.ed.ac.uk/homes/jsteven5
blog: http://all-geo.org/volcan01010

The University of Edinburgh is a charitable body, registered in
Scotland, with registration number SC005336.

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