[Xastir] MrSid format DRG maps

[Tom Russo]

On Tue, Oct 10, 2006 at 06:59:20AM -0700, we recorded a bogon-computron collision of the <archer at eskimo.com> flavor, containing:
> On Mon, 9 Oct 2006, Bennett, Bruce wrote:
> 
> > Does anyone just happen to be working on '.sid' support for xastir a the
> > moment? It would be nice to save disk space for other needs by keeping them
> > in compressed form...
> 
[...]
> 
> Some states have started making MrSID topo maps or perhaps DOQQ
> images available for free.  Sometimes these are cropped USGS images
> (no white border) as well.  Disks are cheap these days and I'd much
> rather see them make the original unmodified files available for
> download.

And many of these MrSID files have been produced with ArcGIS, and therefore
are missing *all* metadata necessary to georeference it properly.  At most
they have an associated worldfile that tells you pixel-to-PCS transformation,
but not what the PCS is.  That makes them a huge PITA to use even after
conversion to open formats, although once you massage them with GDAL to
add metadata they work OK.  

There is a GDAL plug-in that allows the MrSID SDK to be used, but that 
plug-in is only available on linux and Losedows.  When xastir supports
gdal rasters it could theoretically make use of that SDK for anyone who 
was willing to install it and build GDAL with that support (I don't think it's 
especially expensive anymore).  But I'm guessing GDAL raster support is a
fairly distant wish at the moment.

-- 
Tom Russo    KM5VY   SAR502   DM64ux          http://www.swcp.com/~russo/
Tijeras, NM  QRPL#1592 K2#398  SOC#236 AHTB#1 http://kevan.org/brain.cgi?DDTNM
"And, isn't sanity really just a one-trick pony anyway? I mean all you get is
 one trick, rational thinking, but when you're good and crazy, oooh, oooh,
 oooh, the sky is the limit!"  --- The Tick