Markus Neteler neteler at geog.uni-hannover.de
Wed Feb 7 10:45:29 EST 2001

Hi all,

maybe a stupid question, but I don't fully understand how
to interprete the ASCII GRID header of ESRI maps.
I am currently writing a script to generate locations
directly from GIS files.

Example: I have a ESRI header looking like this:

ncols         1121
nrows         1121
xllcorner     3442000
yllcorner     5840000
cellsize      12.5
NODATA_value  -9999

My script detects now:
Checking file: v12_grid.asc
Recognized format: ESRI
north:      5854012.5000
south:      5840000
east:       3456012.5000
west:       3442000
cols:       1121
rows:       1121
N-S Resolution: 12.5
W-E Resolution: 12.5

I am quite sure that this is not what to be written to DEFAULT_WIND.
My problem is to understand the "xllcorner/yllcorner" and the behaviour
of GRASS to store in the middle of a cell, properly.

If I change my script to produce:
north:      5854006.2500
south:      5829993.75
east:       3456006.2500
west:       3441993.75
cols:       1120
rows:       1120   
N-S Resolution: 12.5
W-E Resolution: 12.5

would I get the ESRI data into GRASS correctly referenced?

Help/confirmation would be appreciated.



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