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Re: data model for location information (fwd)

From: Dave Raggett <dsr@w3.org>
Date: Thu, 29 Nov 2007 15:18:33 +0000 (GMT)
To: public-uwa@w3.org
Message-ID: <alpine.DEB.0.99.0711291517590.7018@ivy>

Forwarding Roland's pointer to the RDF schema for location data.

  Dave Raggett <dsr@w3.org> http://www.w3.org/People/Raggett

---------- Forwarded message ----------
Date: Thu, 29 Nov 2007 14:15:29 +0000
From: Roland Merrick <roland.merrick@googlemail.com>
To: Dave Raggett <dsr@w3.org>
Subject: Re: data model for location information

Greetings Dave, the "WGS84 Geo Positioning: an RDF vocabulary" on the W3C
site [1] might be something you could/should work with.

[1] http://www.w3.org/2003/01/geo/wgs84_pos#

Regards, Roland

On 29/11/2007, Dave Raggett <dsr@w3.org> wrote:
>
>> The aim here is to extend the delivery context ontology with
> information on the device's location. This is something we can do
> without having to make any commitments at this stage on specific
> APIs or on privacy issues associated with location information.
>
> Some relevant existing work is:
>
> * JSR179 - location API for J2ME
> * GPX - common XML format for exchanging waypoints
> * EXIF metadata format for JPEG images
>
> The most essential data is the latitude and longitude
> which can be expressed as floating point numbers.
>
> - Latitude is a number in the range [-90.0, 90.0]
>
> - Longitude is a number in the range [-180.0, 180.0]
>
> GPS-based sensors may also be able to determine the altitude.
> This is represented as a floating point number denoting the
> height in metres above the WGS84 ellipsoid.
>
> Estimates of the accuracy of the measurement may be provided.
> A simple approach is to provide estimates of the horizontal
> and vertical accuracy in metres, as per JSR179.
>
> The location measurement may be associated with a timestamp
> and this can be represented in the ISO datetime format,
> e.g. 2007-06-10T01:38:55Z
>
> Further possibilities include the observed speed and course
> based upon a sequence of measurements, and the orientation,
> e.g. the compass azimuth, pitch and roll:
>
> - Speed: metres per second
>
> - Course: degrees relative to true north
>
> - Compass azimuth: horizontal compass azimuth in degrees
>    relative to either magnetic or true north
>
> - Pitch: device tilt in degrees defined as an angle in the
>    vertical plane orthogonal to the group and through the
>    logitudinal axis of the device
>
> - Roll: device rotation in degrees around its own
>    longitudinal axis
>
> - A boolean flag indicating whether the compass reading
>    is with respect to magnetic north or true north.
>
> New kinds of cameras could include GPS sensors for the location,
> magnetic sensors for the compass azimuth, and tilt sensors
> for the pitch and roll. This information could be recorded
> as part of the EXIF metadata included with each image.
>
> Such information could also be used to select points of
> interest to show to the user, and for games as exemplified
> by the Nintendo wii.
>
> It is harder to deal with semantically richer information on
> device location, e.g. street address, as the schema for such
> data varies from one country to another, and moreover it
> complicates how you deal with measurement inaccuracies.
>
> I therefore suggest that we don't include such information in the
> ontology at this stage.
>
> Dave Raggett <dsr@w3.org> http://www.w3.org/People/Raggett
>
>
Received on Thursday, 29 November 2007 15:18:23 GMT

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