How to transfer USGS 1:250k DEM data to grass?

[Mike Hanratty]

In message <Pine.3.89.9607251028.A20842-0100000 at alize.ERE.UMontreal.CA>  writes
:
> 
> Hi everyone,
> 
> I want to transfer some USGS 1:250k DEM data to grass. Is there an 
> available method to do that?
> 
> Thanks in advance!
> 
> Daiyuan Pan

To convert USGS dem files to GRASS format:

1. convert ascii file to binary:
m.dmaUSGSread top=1 bottom=1201 left=1 right=1201 output=binfname 
        logfile=logfname < demfname

2. Rotate binary file 90 degrees, creating dem in lat-long format
m.rot90 [-q] input=binfname output=llfname rows=1201 cols=1201
     bpc=2

3. Convert from lat-long to UTM projection and put in GRASS database
 r.in.ll [-s] input=llfname output=rastfname bpc=2
        corner=corner,lat,lon dimension=1201,1201
        res=3,3 spheroid=wgs72
    The latitude and longitude of the sw corner is the first pair of
the 6-digit values in the header of the original dem file.  These six
digit values are arc-seconds.  Divide by 3600 to get degrees. Enter
these values in the corner= input value for r.in.ll.


I hope this helps.
Mike



Michael Hanratty                               Phone: (612) 627-4590
Dept. of Civil Engineering                            (612) 626-0024
University of Minnesota                        Fax:   (612) 627-4609
St. Anthony Falls Laboratory
Mississippi River at 3rd Ave SE
Minneapolis, MN 55414