[...]
>>> SI units are good.
>> ... Except that these would be quite hard to apply to the (latitude,
>> longitude) pairs as specified by the geo: URIs.
>> The location specification reading ``53 degrees latitude plus/minus
>> 1000 meters, ...'' seems rather unsound to me. I'd expect the
>> deltas' dimensions to align with the corresponding axes' dimensions,
>> as per the CRS used.
[...]
> You make a good point. Maybe it would be best to leave the
> complexity out and we can discuss this in a separate draft.
No objections here, but I'm completely unfamiliar with the
``draft process.''
> This would specify a new "uncertainty" URI parameter and its
> semantics.
I'd rather opt for a set of per-axis parameters.
> I support the idea of uncertainty and would be willing to help.
> On the point of metres uncertainty, that's how we do it.
How ``we'' is defined here?
> For one thing, that makes it more usable by people.
I don't think so. One point is whether we're going to have a
single, or several (one per axis), uncertainty values.
If the latter way is choosen, how would one apply an uncertainty
specified in meters to a value in degrees (like a longitude)?
The former way is no better, as one, once again, cannot easily
reconstruct the area (or volume) within which the object is to
be most likely positioned. At least, one'll have to transform
the projected space's (x', y', z') triplet to the Euclidean
space, make a sphere in that space, using the uncertainty as the
radius, and then transform this sphere back to the projected
space. I didn't much research into these ``volume
tranformations'', but it seems overly complex to me.
... Especially when compared to simply making an axes-aligned
ellipsoid in the selected projected space.
To put it simple, one's going to take a long way to simply draw
the object's likely position area with MapServer (or GRASS),
while with the per-axis, axis-aligned parameters it's simple and
straightforward.
--
FSF associate member #7257
_______________________________________________
Geopriv mailing list
Geopriv@ietf.org
https://www.ietf.org/mailman/listinfo/geopriv
