[Xastir] Wx Alerts

[Tom Russo]

On Mon, Jan 17, 2011 at 01:30:43PM -0800, we recorded a bogon-computron collision of the <curt.we7u at gmail.com> flavor, containing:
> On Mon, 17 Jan 2011, Lynn W Deffenbaugh (Mr) wrote:
> 
> > Please include the Multiline Object information documented in
> > http://www.aprs-is.net/WX/MultilineProtocol.aspx
> 
> The first implementation in a client for that last protocol was Xastir.  Xastir code was written by a guy who was working closely with Dale at the time.  It was _very_ nice to see that up and running.  That protocol worked well to describe the areas.
> 
> 
> > PS.  t/n filter seems to be quiet and even an e/WXSRV* filter only gives
> > me stuff from Australia hence my reluctance to build support for
> > something that's nigh on impossible to test with "real" data...
> 
> I have a test file that I use to test the Xastir code with.  It started as a capture of real data, then got munged to light up different areas in the northwest US.  I could send it your way if it would be useful to you.

Multiline is awesome, and every client should support it.  Curt's test file
is helpful for testing the client's capability.

FWIW, even though the multiline protocol was proposed primarily for WX alert
boxes, it is also a general-purpose "area object" format that is much more
useful than the built-in area objects in the APRS spec.  I use it in my (still
alpha-quality) program for computing DF fixes --- the program spits out 
multiline objects representing probability/confidence regions around position 
fixes.  

Multiline is a much-underused capability.  Having the ability to draw and
transmit such objects from an APRS client would be cool (Xastir has a 
draw-polygon mode for drawing on the local screen, and there is actually a 
so-far-unused subroutine in Xastir that could be used to create the multiline 
object, but the two have never been combined).

One user here once used multiline to transmit a bike race course to share it
among APRS stations at aid stations (used a custom shapefile-to-multiline
program to inject it into Xastir's server port, copying the above-mentioned
unused subroutine to generate the multiline string).

-- 
Tom Russo    KM5VY   SAR502   DM64ux          http://www.swcp.com/~russo/
Tijeras, NM  QRPL#1592 K2#398  SOC#236        http://kevan.org/brain.cgi?DDTNM
 "The truth will set you free, but first it will piss you off."