[GRASS5] New USGS DEM data format

Helena hmitaso at unity.ncsu.edu
Wed Aug 1 18:24:32 EDT 2001


your data appear to be all correct - I worked with this type of data just
and they a far supperior to the 30m data (the mine were created by more accurate
and due to the higher vertical precission they did not have those nasty 1m steps,
they have
other problems though). Your data are correctly in integer decimeters.
Just divide them by 10.  (don't forget the decimal point) in r.mapcalc and you
will get
a floating point DEM in meters with vertical precission in dm. Unless there is
some additional
problem that I don't know about this should do it.


Shepard wrote:

> On Wed, 1 Aug 2001, Rich Shepard wrote:
> >   Second, and more importantly, they have changed the format of the
> > elevation data within the DEM to "decimal meters" which I assume to be
> > fractional meters. The elevations used to be only in integral feet or
> > meters. So, on this basis, more accurate DEM data is a Good Thing. But, they
> > changed the SDTS format to this, and ESRI's ARC/GIS-8 (and Maptitude-5.0)
> > are the only software that can read and translate the new SDTS format.
> > GeoComm, the only site at which these data are available, is an ESRI
> > reseller. Well, leaving out the politics of this arrangement, leaves my
> > question: can r.in.gdal handle the new format with the "decimal meter"
> > elevations?
> >
> >   I've imported a DEM using r.in.gdal, and it didn't complain, but I've no
> > idea what elevation values it has. Anyone know? Frank?
> Follow up:
>   I just ran r.out.ascii on the DEM. It has apparently rounded (or
> truncated?) the elevations to integer values.
>   May I put in a request that this be fixed now? I can't imagine that it
> requires too much work to change an int to a float.
> Thanks,
> Rich
> Dr. Richard B. Shepard, President
>                        Applied Ecosystem Services, Inc. (TM)
>             2404 SW 22nd Street | Troutdale, OR 97060-1247 | U.S.A.
>  + 1 503-667-4517 (voice) | + 1 503-667-8863 (fax) | rshepard at appl-ecosys.com
>                  Making environmentally-responsible mining happen.
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