Subject: Re: [Geopriv] Clarification of comments on Relative Loc draft

From: Hannes Tschofenig <[email-masked]>
Date: Mon, 27 Aug 2007 11:22:38 +0200

Hi James, Hi  Marc,

I read through some of the mails and through the draft 
http://tools.ietf.org/wg/geopriv/draft-linsner-geopriv-relativeloc-01.txt

I think that the schema & instance document suggested in this mail is 
quite good. It allows to express reference points in geodetic and in 
civic form.

I would like to understand the envisioned use cases a bit better since 
they might have an impact on the way how geodetic location information 
is represented, i.e., is it sufficient to use a point only. How is the 
reference location obtained?
Based on your response I wonder whether it isn't more realistic to be a 
bit more flexible with regard to the geodetic reference point.

http://tools.ietf.org/wg/geopriv/draft-linsner-geopriv-relativeloc-01.txt 
seems to envision that the reference point is a named point, for example 
<REFPT>elevator-1</REFPT>.

Although GML allows this usage I wonder whether it wouldn't be better to 
use use the corresponding civic representation. For example:

<location-info>
    <relativeLocation
        xmlns:relLoc="urn:ietf:params:xml:ns:geopriv:relativeLoc">
        <referenceLoc>
            <civicAddress
                xmlns="urn:ietf:params:xml:ns:pidf:geopriv10:civicAddr">
                <country>Germany</country>
                <A1>Bavaria</A1>
                <A3>Munich</A3>
                <A6>Otto-Hahn-Ring</A6>
                <HNO>6</HNO>
                <PC>81675</PC>
            </civicAddress>
        </referenceLoc>
        <xOrientation uom="urn:ogc:def:uom:EPSG::9102">
            45
        </xOrientation>
        <offset uom="urn:ogc:def:uom:EPSG::9001">
            <x>15</x>
            <y>26</y>
        </offset>
    </relativeLocation>
</location-info>

So, my question is: Isn't it sufficient to express the civic location 
reference point as the value itself?

Ciao
Hannes

Winterbottom, James wrote:
> Hi All,
>
> This is just a clarification of my previous comments made on this draft,
> as I am not sure that points I made are quite the points described in
> Marc's final slide. (www.nostrum.com/~rjsparks/RelativeLoc.pdf)
>
> Attached to this email is a very quickly thrown together XML schema that
> crudely defines the form of location I was suggesting (this has
> certainly got bugs in it). An example of what a fragment using this
> schema might look like is included below.
>
> <location-info>
> <relativeLocation
> xmlns:relLoc="urn:ietf:params:xml:ns:geopriv:relativeLoc">
>     <referenceLoc>
>         <gml:Point> -34.25626327 122.44447 </gml:Point>
>     </referenceLoc>
>     <xOrientation uom="urn:ogc:def:uom:EPSG::9102">
>         45
>     </xOrientation>
>     <offset uom="urn:ogc:def:uom:EPSG::9001">
>        <x>15</x>
>        <y>26</y>
>     </offset>
> </relativeLocation>
> </location-info>
>
>
>
> Now to try and describe my view of the orientation parameter. It define
> the orientation of the reference point with respect to North, and set
> the vectors for the subsequent x,y and z offsets. If you look at slide 4
> from Marc's pack, the elevator used as the reference point is oriented
> at about 45 degrees to North. The offset is then measured from this
> position with x being in line with the orientation defined.
>
> I believe that this solution provides everything that Marc's
> specification is trying to achieve, but without introducing x,y, z and
> UOM into the civic form.
>
> Cheers
> James
>
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