[tdwg-content] Inclusion of geo:lat, geo:long, geo:alt in Darwin Core unresolved

[John Deck]

DecimalLatitude and DecimalLongitude are very clear and it is nice to point
to their name as an indication of the restrictions on their contents.

Another issue with geo_lat/geo_lng is that while they can be readily adapted
by certain applications, there are still other ways of expressing
coordinates for consuming applications (e.g.
http://www.w3.org/2003/01/geo/wgs84_pos).  My view is that the data
structures can be clear about what the data contains and communication
between webapps can use geo_lat/geo_long, etc....

John Deck


On Tue, Sep 6, 2011 at 3:49 PM, John Wieczorek <tuco at berkeley.edu> wrote:

> Dear all,
>
> I have reviewed both the recent and ancient discussions regarding the
> proposal to include geo:lat, geo:long, and geo:alt among the
> recommended terms from Darwin Core. This particular proposal is not
> being voted on for inclusion by the TAG at this point, because further
> research has revealed some issues that need to be addressed. I'll
> include here the issues I raised to the TAG in the hope of stimulating
> further discussion in pursuit of a public consensus.
>
> The proposal is to recommend the
> inclusion of the terms from the geo: namespace
> (xmlns:geo="http://www.w3.org/2003/01/geo/wgs84_pos#").
>
> Support in tdwg-content for this request comes from multiple
> independent sources. There has been a long history of discussion
> (http://lists.tdwg.org/pipermail/tdwg-tag/2010-August/000050.html),
> beginning in anticipation of the 2010 TDWG BioBlitz. The proposal has
> gone through the minimum 30-day public review and discussion on the
> forum tdwg-content at lists.tdwg.org:
>
> http://lists.tdwg.org/pipermail/tdwg-content/2011-July/002581.html
>
> There seems to be general support for the additions. However, after
> reviewing the discussions and the references. I have the following
> observations/concerns:
>
> 1) The discussions presented geo:lat and geo:long as W3C standards.
> This is not actually the case. These terms were created by the W3C
> Semantic Web Interest Group in 2003. The documentation for these terms
> (http://www.w3.org/2003/01/geo/) states:
>
> "This document was created as an informal collaboration within W3C's
> Semantic Web Interest Group. This work is not currently on the W3C
> recommendation track for standardization, and has not been subject to
> the associated review process, quality assurance, etc. If there is
> interest amongst the W3C membership in standards work on a
> location/mapping RDF vocabulary, this current work may inform any more
> formal efforts to follow."
>
> These terms do seem to have widespread usage in the semantic web.
> Should we be concerned that they are not part of a standard?
>
> 2) geo:lat and geo:long are not semantically equivalent to the existing
> Darwin Core terms decimalLatitude and decimalLongitude, which have
> been a part of the Darwin Core since it 2003 (or before, if we ignore
> the missing Datum term in earlier versions). The addition of the geo:
> terms as a third set of geolocation terms for Darwin Core raised
> concerns about confusion, having so many spatially-related terms.
> I share this concern. An option would be to
> adopt these terms and deprecate dwc:decimalLatitude, dwc:Longitude,
> and dwc:geodeticDatum. Data that would have occupied these terms would
> go instead to dwc:verbatimLatitude dwc:verbatimLongitude, and
> dwc:verbatimSRS. I see a couple of problems with this. First, most of
> the time the data in the decimal coordinate fields are not the
> verbatim originals, so this would be a misuse of the Darwin Core
> terms. Second, this change would make it more difficult for data
> consumer’s to use existing georeferences. Here’s how. Right now the
> verbatim fields are meant to hold the original coordinate information,
> which means they have a wide variety of content - everything from UTMs
> to custom-encoded coordinates, in any conceivable format. Meanwhile,
> the data in the decimal coordinates fields can be much more readily
> transformed into the desired standardized spatial reference system
> afforded by the geo: terms, because the values are at least
> standardized on geographic coordinates in decimal degrees and only a
> datum transformation has to be done on them to get geo_lat and geo:long.
>
> Do we abandon the dwc: terms decimalLatitude, decimalLongitude, and
> geodeticDatum? Do we abandon them now? Do we build the simplest
> possible tools necessary for anyone to do the transformations so that
> these terms are no longer needed? If so, do we wait until those tools
> exist before we abandon the terms and make millions of georeferenced
> records less readily usable?
>
> 3) A request was expressed by one reviewer that the term geo:alt should
> be added. No one has made a formal request for this. However, if the
> other geo: terms were adopted, it might be silly not to adopt this one
> as well. Doing so would raise a host of issues similar to those raised
> for lat and lng, but related to the Darwin Core elevation terms. No
> discussion
> of these issues has yet taken place.
>
> Cheers,
>
> John
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>



-- 
John Deck
(541) 321-0689
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