[Xastir] Adding offline maps?

[Gerry Creager N5JXS]

At some point, we're gonna have to get reprojection into better shape 
for the Tiger maps.  That said, they're an excellent start, and the 
anomolies you might see won't detract from their utility.

A lot of State governments have started posting GIS data on the Web for 
citizen use.  Texas, for example, has over 4 terabytes of GIS data, 
ranging from transportation to critical infrastructure, maps of the 
Original Texas Land Survey, land use/land cover, hydrology, digital 
orthoimagery, and a plethora of other data.  http://tnris.state.tx.us is 
the home of all this.  Later this year, we're hoping to start linking 
weather data in real time (but of course, you can already get the radar 
overlays and nearly real-time weather that's pretty darned good, now, 
via RF and/or internet!).

Plan to learn more about some of the open source tools.  If you find 
maps with an extension of '.e00' don't despair.  There's a tool that'll 
translate 'em to '.shp'.  MapInfo ('.map') files are a little more 
problemmatical, but not much.

One thing to keep in mind when you're looking, is to make sure you find, 
download, and read the metadata associated with the maps.  It's pretty 
dry, but you need to have a grasp of the information about the data 
(maps), such as geodetic horizontal and vertical datums used in their 
derivation, projections, and accuracy, just as starting points.  It 
hardly does any good, for example, to have a map accurate to 1:100k, 
when you're looking for 2 ft accuracies in your work/play.

Where possible, avoid files compressed with MrSid style encoding.  If 
you have to get them, snag the free reader and use 'em as wallpaper. 
Xastir can't handle the proprietary format.

There's a plethora of older DOS-APRS and WinAPRS maps scattered across 
the net.  Typically, they're not quite as smooth as the GIS products, 
but often very useful if they were created by someone in the local 
community who has an interest in that sort of thing.

In general, look for packages claiming to be in ESRI ShapeFile format 
('.shp') and where possible, snag them in WGS-84 or NAD83 (horizontal) 
datum and NAVD88 vertical datum.  Mean Sea Level (NGVD29) datums have 
some problems associated with 'em.  After all these years, we've 
determined that measuring sea level ain't as scientific as we thought!

Oh... there are a few of us who can become pedantic and petulant when we 
start talking about maps and measurement.  It's usually safe to just 
hide until we quiet down, but sometimes we have some info of interest:-)

73, gerry n5jxs

Steven May wrote:
> First let me say that due to much help from various web sites and posts 
> from the mailing list archive, I now have Xastir running!  (And I am new 
> to anything Unix-like.)  I am running Mac OS 10.3, with an installation 
> of X11, made possible by the excellent instructions on N1OFZ's web 
> site.  i followed his instructions, and Xastir works pretty good. After 
> a bit of reading readme's, etc., I was able to get the program to 
> connect via an APRS server, and also with my Kenwood D7 connected via a 
> USB to serial converter.  Xastir will load the online terraserver, tiger 
> and toposerver maps fine.  Quite a successful weekend's work.
> 
> Since one of my main goals in having Xastir is to provide tracking in 
> the field, away from internet access, I now need to find out how to add 
> maps offline.  I downloaded the Tiger maps that are in shapefile format 
> from http://xastir.tamu.edu/ as a start.  Even after reading more in the 
> readme's and online, I am now stuck as to how to proceed.  If I am to 
> copy the files to the maps directory I have the problem of an error 
> message saying permission denied.  If there is some other program to 
> run, I must have missed seeing it.
> 
> Thanks for any assistance.
> 
> Steve
> N1ESC
> 
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-- 
Gerry Creager -- gerry.creager at tamu.edu
Network Engineering -- AATLT, Texas A&M University	
Cell: 979.229.5301 Office: 979.458.4020 FAX: 979.847.8578
Page: 979.228.0173
Office: 903A Eller Bldg, TAMU, College Station, TX 77843