m.dem.extract

[sktangel at quercus.ecn.uoknor.edu]

Hello Mr. Krueger,
        I read your question on users_list today. I was faced with the same prob
lem some time back. "m.dem.extract" works only for 1:24000 scale DEMs. For the 1
degree chunks we get from the ftp site you have to use m.dmaUSGSread command. th
e procedure is to read the DEM in using the fore mentioned program and then rota
te the product using m.rot90. Then the resulting data can be imported into GRASS
 by "r.in.ll". Try and read the manual for "m.dmaUSGSread" program. It explains 
in detail the syntax and also the use of "dd" with this command. Hope this works. All the best!
Bye,

Sree.


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Dear Sree,
I am trying to use your suggestion to use m.dmaUSGSread, m.rot90, and r.in.ll
for the DEM data I got from the ftp site, but I do not know what information to
supply for some of the parameters these commands ask for.  Specific questions:

1.  When I go to the ftp site to get the DEMs, there is a message that comes up
that says to use the UNIX command: dd if=(inputfilename) of=(outputfilename)
ibs=4096 cbs=1024 conv=unblock.  So do I use this command at the UNIX prompt 
after I get the file from the ftp site, or do I use this command within the
m.dmaUSGSread GRASS command?  And if I do use it in the m.dmaUSGSread command,
do I use the whole command, or just the information that the manual asks for?
(In the manual it does not ask for cbs=xxxx or conv=unblock.)

2.  In the m.rot90 command, it asks for bpc value (bytes per cell).  Where do I
find this information?  And for number of rows and columns, can I just use the
maximum number (1201), or do I have to know the exact number of rows and 
columns?  If I need the exact number, where do I find this information?

3.  In the r.in.ll command, it asks for bpc value again, corner latitude and
longitude, and resolution of the input (in arc seconds).  Where do I find this
information?

Sorry for all the questions, but I have been trying to get these DEMS into
GRASS for three days now, and I am desperate.  Appreciate any help you can
give me.

Ms Jeri Krueger