Re: [Geopriv] Some comments on draft-thomson-geopriv-uncertainty-08

Not claiming I know more than you, but I think E2 and MLP report position AND they report uncertainty by describing the position as a point, and the uncertainty as the radius of a circle or ellipse.  They don’t just sent a circle.  It’s point plus circular uncertainty, not just a circle.  In PIDF, you can’t tell the difference between a location reported as a circle with no uncertainty specified from a point with circular uncertainty.

The definition of the reported position is the lat/lon of the position and the radius of uncertainty.  We have no similar way to report uncertainty in PIDF.

Brian

On Nov 7, 2013, at 2:00 PM, James Winterbottom <a.james.winterbottom@gmail.com> wrote:

> Hi Brian,
> 
> MLP and E2 are essentially the same as what we use in Geopriv
> 
> Sent from my iPad
> 
> On 08/11/2013, at 8:49 AM, Brian Rosen <br@brianrosen.net> wrote:
> 
>> Sure:
>> 
>> When you get a location from a GPS receiver, it typically uses the NMEA interface, which reports a lat/lon and a Dilution of Precision method of specifying uncertainty.
>> MLP usually reports location as point with circle, ellipse or arc uncertainty
>> E2 usually reports location as point with uncertainty
>> 
>> Brian
>> 
>> On Nov 7, 2013, at 1:02 PM, James Winterbottom <a.james.winterbottom@gmail.com> wrote:
>> 
>>> Hi Brian,
>>> 
>>> Can you give an example of point 2 please?
>>> I guess all the systems that I am familiar with use the area to express the uncertainty so I am keen to understand how it might be done differently.
>>> 
>>> Cheers
>>> James
>>> 
>>> Sent from my iPad
>>> 
>>> On 08/11/2013, at 7:48 AM, Brian Rosen <br@brianrosen.net> wrote:
>>> 
>>>> I’ve read this draft, and think it is an excellent explanation of the issues we face in geopriv with measurements.  I highly recommend that we adopt the draft and process it as a work group item.  I am particularly happy with the definitions it offers for the various quantities.
>>>> 
>>>> 
>>>> 
>>>> I find it lacking in two areas:
>>>> 
>>>> 
>>>> 
>>>> 1. I think the draft needs to discuss the issues of comparing measurements with different confidence.  I think the bottom line on that is: don’t do it, use one agreed upon confidence.
>>>> 
>>>> 2. I think we need to stop expressing measurements as just the uncertainty area.  While I understand why doing so is attractive, I think it is not what real systems do.  Real systems express a measurement and explicitly state the uncertainty of the measurement.  I think we need a way to express that.
>>>> 
>>>> 
>>>> 
>>>> Brian
>>>> 
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>> 