[tdwg-tag] DwC change review: geo terms

Javier de la Torre jatorre at gmail.com
Wed Sep 7 00:33:05 CEST 2011

Hi John,

As you mention from previous discussion I would still adopt option number 1 as I believe there is enough tools out there to handle transformations. The current situation I think is much worst on the consumer part and I think is time to think more on data use than on data mobilization. 



On 07/09/2011, at 00:00, John Wieczorek <tuco at berkeley.edu> wrote:

> Perhaps my message was too long for easy digestion and action, as I've
> received no responses. I will take the initiative to initiate option
> 3. No further action from the TAG on this at this point. Be prepared
> though, VOTES by the TAG on publicly resolved issues are forthcoming
> very soon.
> On Sat, Sep 3, 2011 at 9:34 AM, John Wieczorek <tuco at berkeley.edu> wrote:
>> Hi TAGers,
>> I am deep in the review process for the proposed changes to Darwin
>> Core, trying to do due diligence. Some of the change requests are
>> challenging to summarize to determine if there is consensus, in spite
>> of, or because of the discussions. One of the requests on which I’d
>> like some TAG help before proposing a solution is the request for 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:lng 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:lng 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. 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 decimal degrees and only a datum transformation has to
>> be done on them.
>> 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?
>> 3) Additional concern was expressed that the term geo:alt should also
>> 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.
>> I don’t have a good solution. The best short-term one, in my opinion,
>> is to leave Darwin Core as it is, and to recommend that if
>> applications (or aggregators) want to share “cleansed” point-based
>> georeferences, that they do so with the geo: tags, the values for
>> which they derive through transformations to WGS84 of the DwC decimal
>> coordinates and geodeticDatum.
>> Options:
>> 1) Accept the proposal, adding geo:lat, geo:lng, and geo:alt to the
>> list of recommended terms for DwC.
>> 2) Reject the proposal pending further directed research into a
>> comprehensive solution that considers all geospatial terms in Darwin
>> Core (including footprintWKT, for example).
>> 3) Reject the proposal for now, reopening the public discussion with
>> these concerns.
>> Others?
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