m.dem.extract

[Susan Stitt]

>I am a grass user trying to extract a DEM from a tape drive. I have not 
>been very successful. Each time i try to extract the DEM i get the message
>m.rot90:disc quota exceeded. I checked my disc space there is no problem there
>the problem is some where in the execution of the command
>m.dem.extract input='  " output=" " blocksize="  ".
>can some one solve my problem. I am attaching the error message as i read 
>it on the computer.
>    
>min elevation: 0.000000  max elevation: 0.000000
>ns_res: 0.000000  ew_res: 0.000000
># of columns in file = 0
>Making system call to m.rot90
>
>m.rot90 input=/ecn/kittyhawk/rent0/sktangel/macalester.w/practice/.tmp/
>skywarrior.ecn.uoknor.edu/15263.0 
>output=/ecn/kittyhawk/rent0/sktangel/macalester.w/practice/.tmp/
>skywarrior.ecn.uoknor.edu/15263.1  bpc=4  rows=1292400  cols=360
>m.rot90: error writing output file: Disc quota exceeded
>ERROR: can't rotate cell file

I am not sure exactly what you are doing, but did you really have a dem file
with 1,292,400 rows and only 360 columns?  Can you be more specific about what
you told the machine in the m.dem.extract command?  Did you actually leave the
input, output, and blocksize blank?  You need to specify them based on the file
on the tape.  example:

m.dem.extract input=/dev/rmt0 output=elev.quad blocksize=4096

m.dem.extract has historically had problems with tape format variations, 
specific devices, etc. but can work great.  As far as I know, it currently
only extracts 7.5 minute DEM data (1:24000 scale)  NOT 1:250000 scale.  If
your data are the 1:250000 scale data, you need to dd the file and pipe it 
into m.dmaUSGSread, then run m.rot90, and r.in.ll.  See GRASS 4.0 Tutorial: 
DTED and DEM Elevation Data Extraction by Stuart Bradshaw, Mary Martin, 
Chester Kos, and Scott Tweddale, December 1991.

Good luck and have fun!

Susan Stitt

  National Park Service                      
  Geographic Information Systems Division
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  susan%nps at cerl.cecer.army.mil