[GRASS-user] Displaying Multiple Adjacent Raster Maps

Rich Shepard rshepard at appl-ecosys.com
Wed Jan 13 12:53:44 EST 2010

   What I expected to be simple is eluding me.

   Using r.in.gdal I've imported 10m DEM maps for the NE, SE, and SW
quadrants of Oregon to augment the already imported NW quadrant. Now,
however, I'm having difficulties displaying all four simultaneously to make
sure they edge match and cover the entire state. This happens with both the
GUI and the command line.

   I can display only one at a time. It must be a WIND/region issue that I've
not correctly defined, and I don't see what I've missed.

   The rows, columns, and total cells for each map are:

   Quadrant	Rows	Columns		Cells
     NW		18724	24657		461677668
     NE		18856	24779		467232824
     SE		18680	24650		460462000
     SW		18732	24662		461968584

   Using the highest pair of rows (37588) and highest pair of columns (49441)
I set g.region with those totals. The PROJ_UNITS are in feet so I also set
ewres and nsres to 3.048, but one setting overrides the other, so I elected
to go with the rows/columns.

   d.rast draws very slowly, and as soon as I repeat the command with a
different map the first is erased and replaced.

   What is the proper approach to defining a region to accommodate 4 DEM
quadrants? How do I display them all simultaneously on the monitor?


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