[Xastir-Dev] problem with drg geotiff maps

[Gerry Creager]

In this case, I suspect that the quick-n-dirty websearch for DRGE's I 
did may have led Curt astray, and we're really seeing "enhanced" (that's 
bureaucratese for munged) DRGs, sans collar and "rubber-sheeted" to a 
rectangle.  When I get home I can do some more looking and tell a lot 
more.  I don't have the horsepower (I don't think; I'll try to load 
VMWare on the laptop and see if I can make Win9x work with MapInfo) to 
really check out this stuff, and unless I can snag the files tomorrow, I 
  really cannot download 'em via 56k dialup on the road.

I may have time Sat-Mon, while I'm back in town, else it'll have to wait 
until I get back from Boulder and Norman OK.

73, gerry

J. Lance Cotton wrote:
> Curt,
> 
> I don't think what I have are MrSID compressed files. They have the .tif 
> extension and I can `xview` them with the following output from xview:
> 
> [jlc7944 at baconcheddar geotiff]$ xview 309621o.tif
> 309621o.tif: Warning, unknown field with tag 33550 (0x830e) ignored.
> 309621o.tif: Warning, unknown field with tag 33922 (0x8482) ignored.
> 309621o.tif: Warning, unknown field with tag 34735 (0x87af) ignored.
> 309621o.tif: Warning, unknown field with tag 34737 (0x87b1) ignored.
> 309621o.tif is a 5042x5796 8-bit single-plane colormap Macintosh TIFF 
> imageTitled "single-plane "
> Using DirectColor visual
> Building XImage...done
> 
> ImageMagick can read it just fine. I do have some other files in MrSID 
> format, but they're areal photographs and I know ImageMagick won't read it.
> 
> However, I will re-install my MrSID tools and see if I can do anything 
> with that... I'll keep you guys up on my progress.
> 
> 73 KJ5O
> 
> 
> Curt Mills, WE7U wrote:
> 
>> On Wed, 30 Oct 2002, J. Lance Cotton wrote:
>>
>>
>> >Yes, Sorry. Still doesn't draw the DRGE.
>>
>>
>> Just figured out that they use a proprietary compression format
>> called MrSid for the DRG-E files.
>>
>> Here's a blurb from a MicroDEM web page that talks about them.
>> Looks like you might be able to convert them to standard geoTIFF
>> files:
>>
>>
>> "See: http://wgiac.state.wy.us/wsdc/usgs/drg/AboutDRG.html for topo
>> maps in DRG format.
>>
>> See: http://wgiac.state.wy.us/wsdc/drg-e/index.html for the topo
>> maps in DRG-E format. You can download the quads at 1:24,000 scales
>> in MrSid (DRG-E) or GeoTiff (DRG) format. Save the DRG-Es in Geotiff
>> format using the MrSid viewer.  Check metadata and note that the
>> coordinates are in UTM on the NAD27."
>>
>>
>> You might give it a try and see if it works.  If so, I'll add some
>> stuff to the README.1ST file about this map format.
>>
>> Be careful of the NAD27/NAD83 difference.  It's possible that the
>> converted files might be off by a datum shift when used with Xastir.
>>
>