W3C home > Mailing lists > Public > public-geolocation@w3.org > October 2008

Location terminology

From: Thomson, Martin <Martin.Thomson@andrew.com>
Date: Fri, 17 Oct 2008 00:58:23 -0500
Message-ID: <E51D5B15BFDEFD448F90BDD17D41CFF104F7D00D@AHQEX1.andrew.com>
To: <public-geolocation@w3.org>
Having read the draft and the use cases, I think that the API--long overdue as it is--takes the correct approach, particularly with regards to its simplicity.

I was involved in implementing a similar API several years ago; unfortunately, we haven't had the opportunity to follow up on the project.

To preface my future comments, as a regular participant in IETF discussions on geo-location (in the GEOPRIV working group in particular), my interest is in ensuring that there is a degree of compatibility between the approaches taken in both forums.  The goals of these working groups differ, but I see no need in creating solutions that are in conflict.

~~

I notice that in the recent discussion, the question of correct terminology has come up.  In the interests of uniform terminology across the industry, I'd like to make a few terminology suggestions.

    readonly attribute double accuracy;
    readonly attribute double altitudeAccuracy;

Accuracy is a term that can be very easily misinterpreted.  For a quantitative concept, the term "uncertainty" is preferred.  NIST advises that there are two many potential interpretations for accuracy and they prefer it to be used only for qualitative statements.

  http://physics.nist.gov/Pubs/guidelines/appd.1.html


In addition, your specification should make some statement about the expected confidence related to this uncertainty.  You will get a number of opinions on the topic: users and application providers will demand the impossible value of 100%, location providers like lower numbers (because it makes the circle look smaller).  I'd recommend picking between 67%, 90% and 95%, which are commonly used values.  The IETF favour 95% (siding with the users and application providers).


    readonly attribute double heading
    readonly attribute double velocity

Using the term "velocity" for a scalar is misleading, since velocity is a vector concept.  The combination of these two values define the velocity.  "speed" would be a more correct term for the scalar.

Regards,
Martin
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Received on Friday, 17 October 2008 07:48:04 UTC

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