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Re: Geolocation WG taking up work on Orientation/Acceleration

From: Christian Timmerer (ITEC) <christian.timmerer@itec.uni-klu.ac.at>
Date: Tue, 10 Nov 2009 18:02:28 +0100
Cc: Dominique Hazael-Massieux <dom@w3.org>, public-device-apis <public-device-apis@w3.org>, Matt Womer <matt@w3.org>
Message-Id: <FC74B3BB-631A-4EBB-8D2F-0513960561F9@itec.uni-klu.ac.at>
To: Robin Berjon <robin@robineko.com>

Dear Robin,

On Nov 9, 2009, at 5:32 PM, Robin Berjon wrote:

> Hi Christian,
> On Nov 9, 2009, at 15:29 , Christian Timmerer (ITEC) wrote:
>> MPEG-21 DIA Usage Environment Description defines Mobility  
>> Characteristics for a User. The excerpt from the schema you can  
>> find below and the full schema is available at [1]. As this is  
>> somewhat related it might be helpful for (some of) you. If you need  
>> information on the semantics, please let me know.
> I guess that this is more a topic for our Geolocation friends since  
> they're taking over this work item, but in general since I am  
> reasonably confident that very few people here will want to read an  
> XML Schema (let alone chase up dependencies in the MPEG-7 schema :)  
> can you summarise:
I'm sorry, I didn't know that... please find responses to your  
questions below.

>  - what this sub-segment of MPEG-21 does
"There are two tools standardized by DIA that target location-based  
characteristics of a User: mobility characteristics and destination.  
The first of these tools aims to provide a concise description of the  
movement of a User over time. In particular, directivity, location  
update intervals and erraticity are specified. Directivity is defined  
to be the amount of angular change in the direction of the movement of  
a User compared to the previous measurement. The location update  
interval defines the time interval between two consecutive location  
updates of a particular User. Erraticity defines the degree of  
randomness in a User's movement. Together, these descriptions can be  
used to classify Users, e.g., as pedestrians, highway vehicles, etc.  
Destination is a tool to indicate, as the name implies, the  
destination of a User, i.e., an intended location at a future time.  
The destination itself may be specified very precisely, e.g., with  
geographic coordinates, or more conceptually using a specified list of  
terms. In conjunction with the mobility characteristics, this tool  
could also be used for adaptive location-aware services" [1].  If I  
remember correctly, the work is based on [2].

>  - what is particularly good about it that leads you to suggest that  
> we reuse it (or at least take a look)
It is because I think it's related to the subject of this email, in  
particular on "Orientation/Acceleration"...

>  - if there is a WebIDL expression of the same
No but the MPEG Extensible Middleware (MXM) [3] defines APIs to a  
broad range of MPEG technologies.

As said previously, if you need the exact semantics, I can provide it  
and believe me, the MPEG-7 stuff used here is not so complicated as  
one might think. Actually, the mpeg7:GeographicPointType consists of  
three attributes, longitude, latitude, and altitude ;-) The same holds  
for mpeg7:TimeType and mpeg7:probabilityVector

Best regards,

[1] Anthony Vetro and Christian Timmerer, Digital Item Adaptation:  
Overview of Standardization and Research Activities, IEEE Transactions  
on Multimedia, vol. 7, no. 3, pp. 418-426, June 2005.
[2] Sahinoglu, Z.; Vetro, A., "Mobility Characteristics for Multimedia  
Service Adaptation", Signal Processing: Image Communication, Vol. 18,  
Issue 8, pp. 699-719, September 2003 (http://www.merl.com/reports/docs/TR2003-53.pdf 
[3] http://mxm.wg11.sc29.org/

> Concerning the last bit, it's largely because that's what we're  
> dealing with, and it's simpler (and one doesn't have to walk all the  
> XSD inheritance tree to figure out what's on it).
> Thanks!
> --
> Robin Berjon
>  robineko  hired gun, higher standards
>  http://robineko.com/

Received on Tuesday, 10 November 2009 17:03:05 UTC

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