[GRASS5] New USGS DEM data format

Roger S. Miller rgrmill at rt66.com
Wed Aug 1 22:55:11 EDT 2001

Rich Shepard wrote:
> On Wed, 1 Aug 2001, Roger S. Miller wrote:
> > Where did your information come from?  They haven't done that yet, and I
> > don't see any evidence on their site that they intend to ever do that.
> Roger,
>   I just forwarded Bill's message to the GRASS-5 list.

Thanks, I read it.  I guess they made the transition to the
GeoCommunities servers pretty seamlessly.  Or maybe the step from
webglis to earthexplorer *is* the shift to GeoCommunities, in which case
it isn't working very well.
> > They keep threatening to take webglis down and force all traffic through
> > earthexplorer, which would be unfortunate.  I have never gotten
> > EarthExplorer to work right.
>   Me, neither. I wrote to them and explained that it wouldn't work with
> Navigator-4.77, mozilla-0.9.1 or opera-5.0 (identifying itself as MSIE5.0).
> Still broken.

I've written them a couple times about it.  Most recently today.  They
have been announcing that shift for a long time now and just moving the
date back.  Hopefully they will get it right before they force the
shift.  So far, earthexplorer looks like a massive mistake.

> > I would be surprised if they added any accuracy by changing the file
> > format.  In fact, I would be surprise if they changed the file format on
> > anything they already released in an older format.  They put out new
> > digital map data all the time (especially in the 7.5 minute series).
> > Perhaps they are using a new format for the newly released data?
>   Read the article. They _did_ change the data and they modified SDTS
> format. Strangely enough, only ARC/GIS-8 supports that format. And the GS is
> a complete ESRI shop (which is how ESRI got to be as big as they are).

Actually, as I read the article it appears that the format change
they're talking about isn't a change *in* the SDTS format, but the (now
old news) change *to* the SDTS format.  The article is talking about the
differences between the old DEM format (which I think was mostly phased
out more than a year ago) and the SDTS format.

They underestimate the number of applications that read SDTS.  The SDTS
standard was published quite a while ago.  Surfer started importing SDTS
files in version 6, which was released in 1997.  I could have sworn that
GRASS used to have at least a v.in.sdts, but now I can't find it.  I
must be going crazy. Some programs were available from government
agencies for reading SDTS files almost as soon as the standard was

Roger Miller

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