Is the Geo URI uncertainty a radius or a diameter?

Question

Uncertainty is inherent in geospatial data... Maybe it's supposed to be obvious, and, some standards forget to define it.

The RFC 5870 — A Uniform Resource Identifier for Geographic Locations ('geo' URI) — has no clue about the uncertainty measurement definition:

The u ("uncertainty") parameter indicates the amount of uncertainty in the location as a value in meters.

The statistical/metrological uncertainty is a well-known measurement, and usually associated with a disk around the point, but the measurement could be defined as the radius or the diameter of the disk.

Note. If the RFC is really informal, perhaps any set of GIS "trusted books" (or scientific papers) could be used as evidence... It seems that radius is the most widely adopted.

score 2 · Answer 1 · answered Jan 01 '23 at 21:25

2

That RFC refers to uncertainty in RFC5491, and a Wikipedia section on Uncertainty in Geo URIs assesses it to mean the radius of a Gaussian error model containing 95% of the total unit probability. https://en.wikipedia.org/wiki/Geo_URI_scheme#Uncertainty

I've not seen much adoption of the geo: URI so I am not surprised this hasn't really cropped up much.

answered Jan 01 '23 at 21:25

Spacedman

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Thanks Spacedman (!). Well, it remains to be seen if you cited Wikipedia as "authority on the subject", or you agree with what I wrote on Wikipedia in 2019 (and no one has corrected it yet). Ideal is to cite another source — and we can use it also at Wikipedia, is waiting 4 years for it. – Peter Krauss Jan 02 '23 at 10:43
haha. I did think that section was a bit "hand wavy" and lacking in true authority or reference, and did seem like guesswork. But an RFC is a "Request For Comments" so maybe the right thing to do is comment on it, and delete that from WP until there's something definitive. – Spacedman Jan 02 '23 at 12:33

Is the Geo URI uncertainty a radius or a diameter?

1 Answers1