[Xastir] Converting National Geographic Maps?

[Chris Bell]

> 
> The TOPO! CDs that I have are fairly easy to figure out.
> 
> Each map has it's own directory, with a format that is similar to what the
> mapfgd.pl script takes (I haven't tried it, but I assume that it is the
> same).  In each folder are small segments of the map, in .GIF.  Each segment
> is numbered in their own numbering scheme, but if you look at a known map
> vs. the map on the CD, it will take you all of about 30 seconds to figure it
> out.
> 

You are lucky, that is an old version.  They then switched to jpgs,
but the same simple layout, and now are using a combined format that
packs the whole degree worth of jpgs and DEM data into one large file.

> I want to write a script to generate .geo files for each piece, but have
> been a little tied up lately.
> 

I have a script for a jpg set, you should be able to make it work
fairly easily.  As Curt said, this is not an official support, since
these are a commercial product with restrictive licenses and such.

I just want to warn you, it generates *A LOT* of files to manage.  My
data is on a FAT partition so I can still use it via windows, so each
tiny little .geo file uses a big chunk of disk space since the
allocation units are large.  (I think my set of california, 11 cdroms,
is about 7 Gb of files.  The geo files add almost another gig or so.)
Then in xastir it is slow to index all those files (it takes my 1 GHz
laptop about 4 hours to reindex the full set of california), and then
if you have the map chooser to expand directories, it takes 10 minutes
or so to bring up the chooser window.  All that aside, once you have
it running, it is much faster to pan and zoom around compared to the
DRG files, since they are so much smaller.  They also look really
good!

I setup a directory with symlinks into the subdirectories of each zoom
level so I can select an un-expanded directory to get a certain
resolution.  Selecting the directories as they exist on the cdroms
gets all resolutions at once.  You could solve that by putting
reasonable zoom limits in the map chooser properties though.

Chris.
cbell at junknet.com
KD6ZWR