RE: [emergency] RE: Sample email to interestedpartiesWRTgeoenhancements to CAP

["Ron Lake" <rlake@galdosinc.com>]

Art:

Then one says that for such devices there is only one CRS and this is
specified by a particular CRS registry entry.  In either case the
specification of the CRS MUST be unambiguous,  Just agreeing on say
(lat,lon) will not be enough if the different users select for example
different datums as this will lead to the same (lat,lon) corresponding
to different places on the earth. 

Since at the present time, there are not a great number of truly global
alerts - it could make sense to have the single CRS used in one part of
the world differ from that in another part of the world - I think the
key issue is to eliminate ambiguity in the meaning of coordinates.

Ron

-----Original Message-----
From: Art Botterell [mailto:ABott@so.cccounty.us] 
Sent: November 26, 2007 5:17 PM
To: Ron Lake; emergency@lists.oasis-open.org; sandro@oss.com
Subject: Re: [emergency] RE: Sample email to
interestedpartiesWRTgeoenhancements to CAP

Ron, that makes perfect sense for full-blown GIS installation, but what
about cellphones and wristwatches and mass-market alerting devices?
What about systems that receive broadcast, one-way signals?  If they
can't access these remote lookup/conversion services, significant errors
could result.

I'd encourage any of us who weren't around for our earlier CAP
proceedings to at least review the introductory text of the current
spec.  I suspect some aspects of the application domain that may not be
obvious, especially for folks who come from an IT background more than a
telecommunications perspective.

- Art  
-----Original Message----- 
From: "Ron Lake" <rlake@galdosinc.com> 
To:  <emergency@lists.oasis-open.org> 
To:  <sandro@oss.com> 
To: Botterell, Art <ABott@so.cccounty.us> 
 
Sent: 11/26/2007 5:03:20 PM 
Subject: RE: [emergency]  RE: Sample email to interested
partiesWRTgeoenhancements to CAP 
 
Hi Art: 
 
I think this is a good point.  Suppose you use GML geometries in CAP 
constructs.  For example, a GML point is encoded as follows: 
 
<gml:Point srsName = "urn:x-ogc:def:crs:EPSG:4326"> 
	<gml:pos>45.7 110.6</gml:pos> 
</gml:Point> 
 
The srsName attribute indicates the CRS in use.  This does NOT need to 
be resolved in real time, but those wishing to consume or generate this 
data may wish to look this up. This can be done using a registry such as

at http://www.epsg-registry.org and entering the URN string or the EPSG 
code.  A giving alerting community (the whole world or the US or 
whatever) can select the set of CRS definitions that they permit. 
 
If you do not understand the srsName (there could be a default value 
also) then you need to talk to a conversion service or request the data 
in an srsName you do understand. 
 
Cheers 
 
Ron 
 
 
-----Original Message----- 
From: Art Botterell [mailto:ABott@so.cccounty.us]  
Sent: November 26, 2007 4:38 PM 
To: emergency@lists.oasis-open.org; sandro@oss.com 
Subject: Re: [emergency] RE: Sample email to interested 
partiesWRTgeoenhancements to CAP 
 
Let's keep our eye on the ball here.  Our goal isn't adoption of CAP for

its own sake and at any cost.  The purpose of CAP is to achieve 
interoperability among warning systems globally.  
 
 If we start to sacrifice interoperability in pursuit of nominal 
adoptions that can't actually communicate with each other, I'm afraid 
we'll be justly criticised for having lost sight of our real mission.   
 
- Art 
 
 
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