[Xastir] ShapeFile Zone duplicates?

[Curt, WE7U]

On Tue, 1 Mar 2011, Lynn W. Deffenbaugh (Mr) wrote:

> As many of you know, I've been working on Shapefile support in APRSISCE/32 
> and have recently uncovered an unexpected "feature" in one of the NWS 
> shapefiles, specifically c_15jl09.shp.  It seems that this shapefile has 
> multiple objects for a single zone ID and even better, a few of those 
> multiple objects are actually the responsibility of different CWAs (namely 
> FLC087 and VAC099).

That file is out of date.  Check the currently active file "c_01de10" to see if it has the same issues.  You might also check newer ones (which are not supposed to be used yet) listed on the NWS site.

One thing I discovered recently while conversing with David (kd7myc) about these files is that there's an activation date for each of the files, and you want to be using the one that is currently active.  There may be newer ones but you aren't supposed to use them until the date listed.  A bit confusing.

If you find problems like you describe in the active (or newer) files, report them to the people putting the files out.  Some years back I reported that some polygons in the shapefiles crossed the -180 degree longitude boundary.  People at NOAA did respond to my e-mail, saying that their CAD software allowed it, and the resulting polygons were as intended.  Not the result I was looking for, but they did respond which was nice.


> I was wondering how xastir handles this when attempting to light up an area 
> for an NWS message-specified zone?  Currently I just run with the first one, 
> but am considering actually merging the multiple definitions into one and 
> activating the composite results.

We use the first match we find.

-- 
Curt, WE7U.                         <http://www.eskimo.com/~archer>
    APRS:  Where it's at!                    <http://www.xastir.org>
   Lotto:  A tax on people who are bad at math. - unknown
Windows:  Microsoft's tax on computer illiterates. - WE7U.
The world DOES revolve around me:  I picked the coordinate system!"