Subject: [Geopriv] specifying holes in polygons

From: "Winterbottom, James" <[email-masked]>
Date: Wed, 7 Feb 2007 23:29:13 -0600

Hi All,

I was updating the PIDF-LO profile draft when it occurred to me that we
do not have any examples of how one might specify holes in a polygon.
When you are specifying your own location, as is likely to be the case
with a PIDF-LO, I am not convinced that this is a terribly useful thing
to be able to do. When specifying a service boundary map I can see that
it may be an essential thing to do.

For example, I want to specify the boundary for Italy, but I want to
exclude the Vatican. This would be a hole.

I considered putting this an appendix to PIDF-LO profile, but I think
that it would be more useful in a document that talks about specifying
service map boundaries and the associated schema for these interchanges.
The closest document that I could find was
draft-schulzrinne-ecrit-lost-sync-00.txt.

I would be interested in hearing what the rest of the community thought
on this idea.

Cheers
James

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From: "Brian Rosen" <[email-masked]>
Date: Thu, 8 Feb 2007 08:49:34 -0500

Agree: no holes when reporting location, holes allowed when reporting
service boundaries.

Also note you only need one "shape" for position, and a set of shapes for
boundaries (not only holes, but multiple islands).

Brian

> -----Original Message-----
> From: Winterbottom, James [mailto:[email-masked]]
> Sent: Thursday, February 08, 2007 12:29 AM
> To: ECRIT; GEOPRIV WG
> Subject: [Geopriv] specifying holes in polygons
> 
> Hi All,
>

---

From: "Carl Reed OGC Account" <[email-masked]>
Date: Fri, 9 Feb 2007 11:21:21 -0700

GML already supports the ability to identify exterior and interior 
boundaries.

"
<Interior> elements (also known as island, holes, or doughnuts) can also be 
expressed using GML. Interior elements can be expressed using:

<element ref="gml:interior" minOccurs="0" maxOccurs="unbounded" />"

I can provide example snippets if desired.

Carl

---

From: "Winterbottom, James" <[email-masked]>
Date: Fri, 9 Feb 2007 15:27:54 -0600

Hi Carl,

Thanks for the offer. I was aware that GML could do it, and basically
how.
But if you example snippets that will save me from going and producing
some.

Thanks
James

> From: Carl Reed OGC Account [mailto:[email-masked]]
> Sent: Saturday, 10 February 2007 5:21 AM
> To: Winterbottom, James; ECRIT; GEOPRIV WG
> Subject: Re: [Geopriv] specifying holes in polygons
> 
> <Interior> elements (also known as island, holes, or doughnuts) can
also
> be
------------------------------------------------------------------------
> ------------------------
------------------------------------------------------------------------
> ------------------------

---

From: "Carl Reed OGC Account" <[email-masked]>
Date: Fri, 9 Feb 2007 15:45:21 -0700

Will do.

Have a good weekend.

Carl

----- Original Message ----- 
From: "Winterbottom, James" <[email-masked]>
To: "Carl Reed OGC Account" <[email-masked]>; "ECRIT" 
<[email-masked]>; "GEOPRIV WG" <[email-masked]>
Sent: Friday, February 09, 2007 2:27 PM
Subject: RE: [Geopriv] specifying holes in polygons

---

From: "Carl Reed OGC Account" <[email-masked]>
Date: Sat, 10 Feb 2007 18:12:37 -0700

James -

Here is an example. Hope the formatting stays OK!

Please note that the coordinates do not need to be specified one coordinate 
pair per line. You can use gml:poslist to put all coordinates on the same 
line for an element (<gml:posList>12 4.... </gml:posList> tag).

Cheers

Carl

<gml:Polygon>

<gml:exterior>

<gml:LinearRing>

<gml:pos>-117.589 34.127</gml:pos>

<gml:pos>-117.526 34.127</gml:pos>

<gml:pos>-117.526 34.082</gml:pos>

<gml:pos>-117.589 34.082</gml:pos>

</gml:LinearRing>

</gml:exterior>

<gml:interior>

<gml:LinearRing>

<gml:pos>-117.576 34.122</gml:pos>

<gml:pos>-117.559 34.122</gml:pos>

<gml:pos>-117.559 34.107</gml:pos>

<gml:pos>-117.576 34.107</gml:pos>

</gml:LinearRing>

</gml:interior>

<gml:interior>

<gml:LinearRing>

<gml:pos>-117.559 34.107</gml:pos>

<gml:pos>-117.541 34.107</gml:pos>

<gml:pos>-117.541 34.09</gml:pos>

<gml:pos>-117.559 34.09</gml:pos>

</gml:LinearRing>

</gml:interior>

</gml:polygon>

---

From: "Winterbottom, James" <[email-masked]>
Date: Sun, 11 Feb 2007 03:43:15 -0600

Thanks a lot Carl.

Henning, I think that these we would be very good examples to add to an
appendix of your LoST server file protocol exchange draft. They explain
how people such as Michael Haberler can represet holes in their polygon
definitions.

Cheers
James

> Sent: Sunday, 11 February 2007 12:13 PM
> >> > I was updating the PIDF-LO profile draft when it occurred to me
that
> > we
> >> > to be able to do. When specifying a service boundary map I can
see
> > that

---

From: Henning Schulzrinne <[email-masked]>
Date: Sun, 11 Feb 2007 09:46:21 -0500

Since this isn't really specifically about LoST, I'm not sure we need  
to cover that in that particular spec. It is probably worth  
mentioning that this is possible, but normative descriptions of the  
GML would presumably be elsewhere.

On Feb 11, 2007, at 4:43 AM, Winterbottom, James wrote:

> Ecrit mailing list
> [email-masked]
> https://www1.ietf.org/mailman/listinfo/ecrit

---

From: Hannes Tschofenig <[email-masked]>
Date: Sun, 11 Feb 2007 20:59:55 +0100

Maybe we should also add it to the PIDF-LO profile document.
It would fit in there.

Henning Schulzrinne wrote:
> to cover that in that particular spec. It is probably worth mentioning 
> that this is possible, but normative descriptions of the GML would 
> presumably be elsewhere.
>

---

From: "Winterbottom, James" <[email-masked]>
Date: Sun, 11 Feb 2007 14:16:26 -0600

I thought about this, but I can't see a need for a hole is specifying
one's own location. I do however see a need, and other have been vocal
on this, for specifying a hole in a service boundary. I thought that
Henning's document was describing the format for data and how service
boundaries are propagated throughout the network. If it isn't then I
agree with Henning, and another home would be good. If it is, then I
think a section at the end of Henning's document would be a good home.

I think just saying "take a look at GML" is a not a good idea.

Cheers
James

> From: Hannes Tschofenig [mailto:[email-masked]]
> Sent: Monday, 12 February 2007 7:00 AM
> To: Henning Schulzrinne
> Cc: Winterbottom, James; GEOPRIV WG; Carl Reed OGC Account; ECRIT
> Subject: Re: [Ecrit] RE: [Geopriv] specifying holes in polygons
> 
mentioning

---

From: Hannes Tschofenig <[email-masked]>
Date: Sun, 11 Feb 2007 22:03:36 +0100

Hi James,

the PIDF-LO Profile document contains a section about shapes relevant 
for emergency services.
I wonder why it does not fit in there.

Ciao
Hannes

Winterbottom, James wrote:
>>> Since this isn't really specifically about LoST, I'm not sure we
>>>       
> need
>

---

From: "Winterbottom, James" <[email-masked]>
Date: Sun, 11 Feb 2007 15:20:08 -0600

Hi Hannes,

But the general flow of the PIDF-LO profile document is how to craft and
use a PIDF-LO to represent your location, and also applies to the
emergency shape section. The emergency shape section basically says be
careful because not all shapes may be acceptable for emergency service
applications in all areas.

I guess I don't see a PIDF-LO containing a polygon that requires a hole
in it, and that is my reasoning for suggesting that PIDF-LO profile is
not a good fit for this discussion.

Cheers
James

> Sent: Monday, 12 February 2007 8:04 AM
> To: Winterbottom, James
> Cc: Henning Schulzrinne; GEOPRIV WG; Carl Reed OGC Account; ECRIT

---

From: "Marc Berryman" <[email-masked]>
Date: Mon, 12 Feb 2007 06:32:49 -0600

I have though about this over the weekend and must agree with James (in
part anyway). I can not think of a scenario where one would need to pass
a polygon with a hole (or doughnut) in it as part of a PIDF-LO. 

There are many cases where the information used to route the PIDF-LO
must be able to support polygons with holes, but not the actual
information within the PIDF-LO.

Marc B

-----Original Message-----
From: Winterbottom, James [mailto:[email-masked]] 
Sent: Sunday, February 11, 2007 3:20 PM
To: Hannes Tschofenig
Cc: GEOPRIV WG; ECRIT; Henning Schulzrinne
Subject: RE: [Ecrit] RE: [Geopriv] specifying holes in polygons

Hi Hannes,

Cheers
James

---

From: Henning Schulzrinne <[email-masked]>
Date: Mon, 12 Feb 2007 08:40:32 -0500

Maybe this leads to a slightly different approach. Rather than  
targeting PIDF-LO as only a means of specifying locations for  
presentities, another view is that the profile document enumerates  
and describes standard representations for geographic shapes in  
GEOPRIV/IETF-geo related work.

My fear is that the donut is not just useful for LoST but for other  
applications outside that protocol. Thus, rather than having each  
protocol specify GML subsets, it seems useful to gather them in a  
protocol-neutral place.

Even for PIDF-LO, one could, with a bit of a stretch of the  
imagination, imagine a use for donuts, say, for a GPS-game or  
geocaching where the hint is "I'm somewhere on the lake front, but  
not including the water itself".

Henning

---

From: "Marc Berryman" <[email-masked]>
Date: Mon, 12 Feb 2007 07:55:43 -0600

Using the example of  "I'm somewhere on the lake front, but not
including the water itself", would be where the application using the
information sent in the PIDF-LO would be used (to define the water say).

I think that the set of protocols used for PIDF-LO is a small subset of
those that are used to describe representations for geographic shapes. 

Marc Berryman, ENP
Geographic Information Systems
Greater Harris County 9-1-1 Emergency Network
Houston, Texas      (713) 407-2254
[email-masked]

-----Original Message-----
From: Henning Schulzrinne [mailto:[email-masked]] 
Sent: Monday, February 12, 2007 7:41 AM
To: Marc Berryman
Cc: Winterbottom, James; Hannes Tschofenig; GEOPRIV WG; ECRIT
Subject: Re: [Ecrit] RE: [Geopriv] specifying holes in polygons

Henning

On Feb 12, 2007, at 7:32 AM, Marc Berryman wrote:

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