[Xastir] Speeding up map processing?

[Curt, WE7U]

On Wed, 23 Jul 2008, Andreas Weller wrote:

> I converted a map for Xastir usage. This resulted in a 4000x4000 px PNG
> with abt. 20 MB size.
> Processing this with Xastir is rather slow. Is there any way in speeding
> up processing this raster data? For example whole germany at 1:50000
> level results in a 1 GB GeoTIFF...
> How can I convert these big files into smaller tiles which are processed
> just in time by Xastir when they are really in view?

Any image processing program that can convert them to smaller tiles
should work, then you'll have to create a .geo file for each of the
tiles.  Xastir will work well with that, displaying only those tiles
that fit the current view.

Another method that many use is to define map levels for each type
of map.  This way the higher-level overview maps will only be
displayed when zoomed way out, detailed maps will be used when
you're zoomed in.  Take this scheme to as many levels as you wish.


> Another thing I thought about:
> Can I convert the Openstreetmaps data to a vector file format usable
> with Xastir?

I don't know what vector format they're in now.  If you can find
something to convert them to ESRI Shapefile format, it's likely they
can be used in Xastir.  You'll need to assure the vertices are in
lat/long format and preferably WGS84 or NAD83 datum, plus you'll
more than likely need to create your own dbfawk file to get them
displayed and colored as you prefer.

-- 
Curt, WE7U.				archer at eskimo dot com
http://www.eskimo.com/~archer
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