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Subject: [emergency] RE: Sample email to interested parties WRT geoenhancements to CAP

Friends -

We may want to think a bit more about the "what" before we dive too deeply into the "how."  Experience has revealed some ambiguities in the semantics of the existing CAP geospatial elements, and I think addressing those may help us understand better exactly what sort of geospatial elements will best meet the functional requirements.

One of those ambiguities has to do with whether the CAP Area element describes the area directly affected by a hazard, the location of the hazard itself, or the area to which information about the hazard should be routed.  All three are legitimate topics, but they don't necessarily raise the same requirements.  I'm not sure, for example, that there would be any meaningful use of a line or point in describing an affected area or a message-targeting area, while a hazard location might be a point and a hazard in motion (see below) might be described as a line or an unterminated vector.

The temporal dimension is another aspect I'm thinking we may not have addressed fully.  Currently the only formal way to describe motion or trends in CAP is by means of a set of Info blocks each with its own <effective> and <expires> values... in effect, a set of "key frames" which might or might not imply some continual transition between the described states.  I notice that NWS has recently started adding motion vectors (starting location, direction and rate) to its geospatial descriptions in storm warnings.

And of course one of the long-standing requirements for CAP generally is that it be easy to process on autonomous devices with various kinds and degrees of connectivity.  That's why I have some anxiety about the idea of supporting multiple coordinate systems... do we risk making it impractical for lightweight devices to know about all the possible coordinate systems?  My mind is open on that, but I hope we'll keep in mind the differences between the requirements for a full-blown GIS application and those for a portable (e.g., wristwatch-sized) or embedded system.

- Art

Art Botterell, Manager
Community Warning System
Contra Costa County Office of the Sheriff
50 Glacier Drive
Martinez, California 94553
(925) 313-9603
fax (925) 646-1120

>>> "Carl Reed OGC Account" <creed@opengeospatial.org> 11/16/2007 11:44 AM >>>
Hi All -

We would like to get this email out to all interested CAP parties so that we can collect requirements and move forward. I originally sent this email in September and only heard from Rex. Other feedback would be appreciated. 

Thanks and regards


----- Original Message ----- 
From: Carl Reed OGC Account 
To: emergency@lists.oasis-open.org 
Sent: Wednesday, September 12, 2007 8:24 AM
Subject: [emergency] RE: Sample email to interested parties WRT geo enhancements to CAP

A bit tardy :-)

First stab at a letter to interested party to collect additional requirements for geo enhancements to CAP and by extension to EDXL.



Dear < >

CAP has now been widely implemented. As a result, we are beginning to receive considerable feedback regarding implementation experience, especially in the realm of requirements for enhanced capabilities to express additional (and richer) geographic elements. Some suggestions have been to allow additional coordinate reference systems in addition to WGS-84, the ability to encode point, line, and route features, and the ability to reference the output of a plume model have been suggested.

Therefore, in order to document a consistent set of requirements for potential enhancement or extensions to CAP, we are seeking your input and experience. Please note that we are not seeking input on how to change CAP or to implement changes in CAP. We are instead seeking either use cases or new requirements for using/encoding/referencing geospatial content in a CAP message.

Thank you for your help and consideration.


Carl Reed (CTO, OGC)
OASIS Emergency Management TC GIS SC Chair.
Carl Reed, PhD
CTO and Executive Director Specification Program

The OGC: Helping the World to Communicate Geographically


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