[Xastir] USGS DRG files no longer free..

[Curt Mills, WE7U]

On Sun, 5 Oct 2003, Tyler Allison wrote:

> Looks like the USGS has now "partnered" with a commercial group that
> charges an arm and a leg for the DRG maps and they've removed the 'free'
> download. (something like $75 per grid, which would cost me over $1000 to
> get the topos for Kentucky)
> 
> I found the following Kentucky State website to download DRG files im
> interested in:
> http://ogi.ky.gov/data/drg/drgzone.htm

There were two partnerships that I recall.  They've have existed
quite a while.  One was in the KY/TN area, another was in CA.  I
don't know if those two area were ever available as free downloads.


> However, I downloaded one of the tif files and of course it doesnt come
> with a fgd file and the file is not in USGS name format so the perl script
> that creates fgd files that comes with Xastir doesnt work.

If you change it to USGS name format, the script should work.


> So I created a bogus fgd file using the README.MAPS information just to
> see if it would load anywhere in the world.  However, it looks like the
> TIF file was created using the commercial library of tiff so it's using a
> compression format that was removed from libtiff due to lawsuits and what
> not...what that means it that xastir is trying to access the file in
> 'random access' mode which is not support by libtiff with that type of
> compression.

Was it MrSID compression?  If so, you're out of luck.  That's a
proprietary compression format.  Then again, perhaps the GDAL library
might have some MrSID decompression in it?  We've been working on
adding that library to Xastir, but I haven't heard much about that
project for a while.

Another method might be to use the MrSID tools to decompress it, then
either save the decompressed file or take a screen snapshot of it in
order to use it in Xastir, depending on what the capabilities of
their free viewers are.


> So I use tiffcp to 'uncompress' the file. I get a couple errors about some
> lines ignored because of bad format or what not but the new files reads
> okay in my various graphic viewing software.

It probably got rid of the geotiff tags.  You need those.  You can use
some tools to snag those out of the original file and then add the tags
back in to the file after you convert the file to the proper format.


> I put the new tiff in the maps directory for Xastir and Xastir prints an
> error every time it tries to load the map:
> 
> Problem in translating
> Problem in translating
> 
> Anybody know how I can get these tif's to work in Xastir?

Just the ideas I had above.  Even the normal DRG's need to be in a
particular geoTIFF format.  The OziExplorer site had some info on
converting to this format.


> Or a place to download the USGS name formated tif's without paying my
> first born for them?

There are DRG sharing groups around.  You might contact some of them
to see what quads they have and do some trading.


> ps: does it make anybody else mad that their taxes paid for the USGS topo
> work yet you have to pay to get what your tax dollars paid to create?

Yes!  Some of the states are putting out MrSID compressed format
files that they call Enhanced DRG files.  We can't do much with them.

Curt, WE7U.				archer at eskimo.com
http://www.eskimo.com/~archer
  Lotto:  A tax on people who are bad at math. - unknown
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