[Xastir] Map formats and ordering

[Tom Russo]

On Thu, Jan 21, 2010 at 01:02:02PM +1100, we recorded a bogon-computron collision of the <ibennett at tpg.com.au> flavor, containing:
> 	I use Oziexplorer when 4WDing and have collected a LOT of topo maps over the 
> years and would like to use them in Xastir. Problem is ECW and DrSid formats 
> are not supported. I vaguely remember something about Xastir using ImageMagik 
> for image processing so maybe I should hit them up??

Your only choice for using ECW and MrSID images is to convert them to GeoTIFF.
Xastir handles GeoTIFF just fine, and most of us who use topo maps use them
in GeoTIFF format.

There are multiple routes for that.  For ECW, you can download the source code
for the ECW SDK from www.erdas.com, and build it; it's a free download, but
not open-source --- you have to register, accept a license agreement, and
then get the code.  Then you can build GDAL with ECW support, and use 
gdal_translate (or gdalwarp, depending on what coordinate system your ECW 
images are in) to create geotiff files.  They'll need to be in either UTM 
projection or equidistant cylindrical ('lat/lon') projection for Xastir to use 
them.

For MrSID you might also have an option to download the MrSID SDK in binary form
and link it in to GDAL.  Last time I checked, though, the versions available
for linux were for compilers so old that you couldn't use it on any recent
Linux distro.  The one they have there now is compiles with gcc 4.1, and
even the system I keep at Ubuntu 8.04 has only gcc 4.2 --- libraries for the
one won't link with the other.

The other choice for MrSID is to download the "mrsiddecode" application from
lizardtech at http://www.lizardtech.com/download/dl_options.php?page=tools
With this you can create geotiff files from MrSID files.

In both cases, your ECW and MrSID files need to be properly georeferenced.  In
both cases, the result will be files that are absolutely enormous compared
to the compressed files.  Both ECW and MrSID are extremely efficient 
compression algorithms.

ImageMagick is not the right project to hit up here.  The support for
ECW and MrSID would be in GDAL --- and right now, Xastir doesn't use GDAL for
raster access.  There is embryonic code in the repository to use GDAL for this,
but it was never finished.  If it ever is, then one could link Xastir with
an ECW and MrSID-enabled GDAL library and use those files directly.  But the
code in map_gdal.c was started in 2003 and only vector handling was ever
made to work.  So I wouldn't hold my breath if I were you.

-- 
Tom Russo    KM5VY   SAR502   DM64ux          http://www.swcp.com/~russo/
Tijeras, NM  QRPL#1592 K2#398  SOC#236        http://kevan.org/brain.cgi?DDTNM
  In some cultures what I do would be considered normal. 
                                  -- Ineffective daily affirmation