Re: [netmod] Benjamin Kaduk's Discuss on draft-ietf-netmod-geo-location-08: (with DISCUSS and COMMENT)

[Benjamin Kaduk <[e-mail]>]

On Sat, Jul 17, 2021 at 07:17:09PM -0400, Christian Hopps wrote:
> 
> 
> > On Jul 17, 2021, at 6:14 PM, Benjamin Kaduk <[e-mail]> wrote:
> > 
> > So, when we refine the coord-accuracy and height-accuracy for an
> > instantiation of the grouping, what does that mean?
> 
> It’s supposed to mean the accuracy of the measurement that is recorded in the grouping. So if the coord-accuracy is .1 and the measurement is lat/long then the accuracy is within 1/10 of a decimal degree. if the measurement is in cart coordinates the accuracy would be 100cm. I don’t think we need to make this anymore complex than that. Is there some text you would like to see to make that clearer?

The accuracy of the measurement with respect to what?  The coordinate
system, or the actual physical object?

And, if the concept here is that "I made a measurement, and my measurement
device reported a value to 1/10 of a decimal degree", that would typically
correspond to a "precision" rather than an "accuracy"
(https://en.wikipedia.org/wiki/Accuracy_and_precision).

In either case, I think that "accuracy of the measurement recorded in the
grouping" is a qualitatively different concept of "accuracy" than the
listed accuracy of the geodetic-datum, which (AIUI) relates to the maximum
deviation between the model of the object used by the coordinate system and
the actual physical object.  So it's not really clear that we should be
talking the one "overriding" the other.

-Ben