Seems we are on the same page, Robert
At the moment, I am preparing (for the BioGeomancer project) a document oin "Best Practices for Georeferencing" which will discuss in detail how to calculate Uncertainty. At the moment, we are using a Point Radius Method (hence the Darwin Core element), but this is likely to move to footprinting in the future. Also be aware, that the Geospatial Elements are being removed from Darwin Core 2, to be obtained via an Extension related to GML. These will still include Uncertainty Elements.
Cheers
Arthur D. Chapman
From "Robert K. Peet" peet@unc.edu on 9 Feb 2006:
From: "Lynn Kutner" Lynn_Kutner@natureserve.org
"An observation characterizes the evidence for the presence or absence of an organism or set of organisms through a data collection event at
a
location. Observations are not necessarily independent and could be linked via characteristics such as time, place, protocol, and co-occurring organisms."
I am happy with something close to this.
- location
I (Lynn) suggest: (a) Location information be required, preferably geocoordinates and mapping precision, but if not available then a text description and
the
finest level of geolocation using the Darwin Core attributes.
(b) Location data include the representation of observations as point, line, or polygon data (with the necessary spatial metadata).
I agree, however, I would like to include a measure of uncertainty. Darwin Core has such an element, CoordinateUncertaintyInMeters, that would work. "The upper limit of the distance (in meters) from the given latitude and longitude describing a circle within which the whole of the described locality must lie. Use NULL where the uncertainty is unknown, cannot be estimated, or is not applicable."
- could be linked
Can have a pointer or pointers to other observations, thereby creating aggregate observations. Note that commonality of date, time, place, etc. is not sufficient in that the none of the observation authors explicitly made the connection
Some revision along these lines would be helpful.
From: tdwg@achapman.org
The word 'protocol' what does this mean in this context?
In your Locality definition a). I don't think you mean Mapping Precision here - it is only one aspect of accuracy/uncertainy. Also -
not all coordinates will be attached to a map (e.g. GPS). I prefer
any
of the the terms 'Uncertainty', 'Accuracy' or 'Maximum Error' (or all three/four with Precision). They are all slightly different in
meaning.
See my note above about the Darwin Core element CoordinateUncertaintyInMeters.
My other suggestion revolves around the mention of Darwin Core here -
is
it necessary - some may be using ABCD, etc. and should we necessarily have the definition tied to a protocol
We don't need to be tied to a standard, but the closer we come to being consistent with the rest of the community, the more likely our standard is to be widely accepted. In short, I like following the Darwin Core where
it works for us, but I see no need to explicitly refer to the Darwin Core. Neither the Darwin Core or ABCD will work for us when it come to taxonomic identification and there we will need to use the TDWG TCS schema.
From: Hannu Saarenmaa hsaarenmaa@gbif.org
"set of organisms" doesn't sound very natural to me. What about "group
of organisms"? However, doesn't the second sentence covers this
anyway?
"Set of", or "group of", or "assemblage of" all work for me.
Bob
====================================================================== Robert K. Peet, Professor & Chair Phone: 919-962-6942 Curriculum in Ecology, CB#3275 Fax: 919-962-6930 University of North Carolina Cell: 919-368-4971 Chapel Hill, NC 27599-3275 USA Email: peet@unc.edu http://www.unc.edu/depts/ecology/ http://www.bio.unc.edu/faculty/peet/ ======================================================================
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