Subject: [Geopriv] coordinates

From: Ron Shacham <[email-masked]>
Date: Wed, 16 Nov 2005 15:35:40 -0500 (EST)

Hello.

We have found it useful in a tracking application at Columbia to support
the notion of coordinates within a specific place, and represent this in 
a presence document.  For example, in an auditorium, we wish to keep track 
of a user's (X, Y, Z) coordinates, with respect to a corner that is chosen 
as the point of reference. Although the pidf-lo format borrows an existing 
format for representing civil location, might it nevertheless be useful to
extend the format to include such a coordinate element?

Regards,
Ron

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From: "James M. Polk" <[email-masked]>
Date: Wed, 16 Nov 2005 15:08:17 -0600

Ron

The PIDF-LO already supports coordinates, borrowing from GML. In GMLv3.0 
they define an XY or an XYZ as a point. In GMLv3.1, they changed "point" to 
"pos" (for position) to get away from the aspect of defining the precision 
related to a point.  Here is a paragraph at the bottom of page 5 from the 
PIDF-LO ID 
http://www.ietf.org/internet-drafts/draft-ietf-geopriv-pidf-lo-03.txt that 
discusses this, including giving a good reference (with section) for the 
coordinate examples:

"
The Geography Markup Language (GML) is an extraordinarily thorough and 
versatile system for modeling all manner of geographic object types, 
topologies, metadata, coordinate reference systems and units of 
measurement. The simplest package for GML supporting location information 
is the 'feature.xsd' schema. Although 'feature.xsd' can express complicated 
geographical concepts, it requires very little markup to provide basic 
coordinates points for the most common use cases. Various format 
descriptions (including latitude/longitude based location information) are 
supported by Feature (see section 7.4.1.4 of [16] for examples), which 
resides here:
         urn:opengis:specification:gml:schema-xsd:feature:v3.0
"

This should give you a hint that this spec does cover XY and XYZ 
coordinates and where to look for the text of this description.

At 03:35 PM 11/16/2005 -0500, Ron Shacham wrote:
>the notion of coordinates within a specific place, and represent this in a 
>presence document.  For example, in an auditorium, we wish to keep track 

cheers,
James

                                 *******************
                 Truth is not to be argued... it is to be presented.

---

From: "Carl Reed OGC Account" <[email-masked]>
Date: Wed, 16 Nov 2005 14:17:30 -0700

You could do this using the GML 3.1.1 option in PIDF-LO - would require a 
profile/schema of GML.

Carl

---

From: Henning Schulzrinne <[email-masked]>
Date: Wed, 16 Nov 2005 16:15:25 -0500

James,

let me try to add a bit of perspective to Ron's note. The issue is that 
we're dealing with combined geo/civic coordinates. What we'd like is to 
be able to say something like:

"User is 3 m to the left, 5 m ahead of the (defined) corner of the Polk 
Auditorium, located at 1214 Amsterdam Avenue, NY, NY". (The University 
will gladly discuss with you how to get your own named auditorium...)

There are several applications for that:

- directing cameras during classes and lectures
- people proximity detection in large indoor venues such as stadiums and 
convention centers
- directional microphones
- matching faces and speakers
- directing jets of water to owners of ringing cell phones
etc.

I don't think the use of standard geo coordinates (long/lat degrees) 
would be rather inconvenient in this case. Can GML express these types 
of reference-point relationships?

Henning

James M. Polk wrote:
> they define an XY or an XYZ as a point. In GMLv3.1, they changed "point" 
> to "pos" (for position) to get away from the aspect of defining the 
> precision related to a point.  Here is a paragraph at the bottom of page 
> 5 from the PIDF-LO ID 
> http://www.ietf.org/internet-drafts/draft-ietf-geopriv-pidf-lo-03.txt 
> that discusses this, including giving a good reference (with section) 
> for the coordinate examples:
> 
> "
> measurement. The simplest package for GML supporting location 
> information is the 'feature.xsd' schema. Although 'feature.xsd' can 
> express complicated geographical concepts, it requires very little 
> markup to provide basic coordinates points for the most common use 
> cases. Various format descriptions (including latitude/longitude based 
> location information) are supported by Feature (see section 7.4.1.4 of 
> [16] for examples), which resides here:
>> the notion of coordinates within a specific place, and represent this 
>> in a presence document.  For example, in an auditorium, we wish to 
>> keep track of a user's (X, Y, Z) coordinates, with respect to a corner 
>> that is chosen as the point of reference. Although the pidf-lo format 
>> borrows an existing format for representing civil location, might it 
>> nevertheless be useful to

---

From: "Carl Reed OGC Account" <[email-masked]>
Date: Wed, 16 Nov 2005 14:32:01 -0700

As a follow on to James' excellent synopsis, there is a new profile of GML 
3.1.1 that will soon be an official OGC Profile Implementation 
Specification. It is titled, "GML Profile for Simple Features" and can be 
found http://portal.opengeospatial.org/files/?artifact_id=11266. This is the 
version that was provided for public comment. The editing team has worked 
the comments and a new version will be posted in the near future.

This profile of GML was defined to 1.) make it easier for developers to use 
GML (don't have to worry about the entire GML package) and 2.) enable a 
higher degree of interoperability for applications using this profile.  In 
OGC/ISO parlance, a profile is a restricted subset of a core OGC 
Implementation Specification.

Hope that this is of use.

Regards

Carl

----- Original Message ----- 
From: "James M. Polk" <[email-masked]>
To: "Ron Shacham" <[email-masked]>; <[email-masked]>
Cc: <[email-masked]>
Sent: Wednesday, November 16, 2005 2:08 PM
Subject: Re: [Geopriv] coordinates

> precision related to a point.  Here is a paragraph at the bottom of page 5 
> from the PIDF-LO ID 
> is the 'feature.xsd' schema. Although 'feature.xsd' can express 
> complicated geographical concepts, it requires very little markup to 
> provide basic coordinates points for the most common use cases. Various 
> format descriptions (including latitude/longitude based location 
> information) are supported by Feature (see section 7.4.1.4 of [16] for 
> examples), which resides here:

---

From: "James M. Polk" <[email-masked]>
Date: Wed, 16 Nov 2005 15:55:07 -0600

Henning

I wasn't sure what Ron meant (it was one of two), so I guessed wrong with 
how to respond. My bad...

I see the needs you list below as quite valid, and can come up with several 
more.  I see this as an instance of the "where's the nearest Pizza Hut to 
me" question we brought up years ago.

What we're talking about here is the delta (in each direction/dimension) 
from a known point in either format. I don't have my version of GMLv3.0 or 
v3.1 in front of me at the moment, but I would be amazed if this wasn't 
accounted for in the 550 page spec (as everything else was  ;-)

And if it is in that spec, we ought to use it here. I'm afraid Ted is going 
to have a cow with the thought of this fairly advanced usage written in an 
ID somewhere... d`oh!

BTW - when I win the Trump Lotto, I'll be calling someone at Columbia about 
naming rights...

At 04:15 PM 11/16/2005 -0500, Henning Schulzrinne wrote:
>we're dealing with combined geo/civic coordinates. What we'd like is to be 
>able to say something like:
>
>I don't think the use of standard geo coordinates (long/lat degrees) would 
>be rather inconvenient in this case. Can GML express these types of 
>reference-point relationships?
>
>Henning
>
>James M. Polk wrote:
>>Ron
>>that discusses this, including giving a good reference (with section) for 
>>the coordinate examples:
>>"
>>>a presence document.  For example, in an auditorium, we wish to keep 
>>>track of a user's (X, Y, Z) coordinates, with respect to a corner that 
>>>is chosen as the point of reference. Although the pidf-lo format borrows 
>>>an existing format for representing civil location, might it 

cheers,
James

                                 *******************

---

From: "Carl Reed OGC Account" <[email-masked]>
Date: Wed, 16 Nov 2005 16:52:07 -0700

Just to show that James is correct in his assumption regarding that he would 
be amazed if this requirement is not accounted for, this from the "father" 
of GML:

"IF I understand here the bottom line is whether or not we can support
rectilinear coordinate systems.  The answer is yes - and of course for
the example quoted one would need to define the coordinate system."

Cheers

Carl

----- Original Message ----- 
From: "James M. Polk" <[email-masked]>
To: "Henning Schulzrinne" <[email-masked]>
Cc: <[email-masked]>
Sent: Wednesday, November 16, 2005 2:55 PM
Subject: Re: [Geopriv] coordinates

> I see the needs you list below as quite valid, and can come up with 
> several more.  I see this as an instance of the "where's the nearest Pizza 
> Hut to me" question we brought up years ago.
>
> And if it is in that spec, we ought to use it here. I'm afraid Ted is 
> going to have a cow with the thought of this fairly advanced usage written 
> in an ID somewhere... d`oh!
>
> BTW - when I win the Trump Lotto, I'll be calling someone at Columbia 
> about naming rights...
>