USGS data usage in GRASS
Kemal Gurer
gurer at cumulus.rutgers.edu
Tue Oct 17 08:00:00 EDT 1995
Dear GIS colleagues,
I am trying to read USGS DEM and LULC data into GRASS but data appears to
be nowhere in the display. I would appreciate if one kind soul can tell me
what I should do to correct the problem. Here is what I did step by step:
1) got a sample data "new_york-e.gz" from edcftp.cr.usgs.gov in
"/pub/data/DEM/250/N"
2) unzipped it,
3) applied the following conversions:
dd if=new_york-e ibs=10240 | m.dmaUSGSread top=1 bottom=1201 \
left=1 right=1201 output=demtest logfile=log
and rotated it
m.rot90 input=demtest output=demtest.r90 rows=1201 cols=1201 bpc=2
Now, after this step I needed to set the frame of the data region. But the
only information given for the data resides within the file in UTM
coordinates and there is no .txt file that I can get information. Header
lines of the data gives the information that data has 1201 columns, its
resolution is 3 arc seconds and its four corners are shown as:
Ground Coordinates of the 4 corners of the DEM:
-0.262800000000000D+06:
0.144000000000000D+06:
-0.262800000000000D+06:
0.147600000000000D+06:
-0.259200000000000D+06:
0.147600000000000D+06:
-0.259200000000000D+06:
0.144000000000000D+06:
Finally, the last step
r.in.ll input=demtest.r90 output=dem.utm3 dimension=1201,1201 bpc=2\
res=3,3 corner=sw,41N,74W spheroid=wgs72
Here, I assigned the lat-lon info from a map (roughly). When I display the
data, however, a box of data is plotted but with zero height and
message is displaced stating "no data". I tried a larger area to
give cushion regions so that I can guarantee to capture the data; it did
not work either.
I would appreciate if one could give me an answer on how to solve the
displaying the data. With my best regards. Sincerely.
Kemal Gurer
Department of Environmental Science
Rutgers University
New Brunswick, NJ 08903
(908) 932 9588
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