[tdwg-tag] DwC change review: geo terms

John Wieczorek tuco at berkeley.edu
Wed Sep 7 01:13:41 CEST 2011

Can I ask that, since this subject has been put back into the public
forum, that the conversation be moved over there from the TAG? If so,
Hilmar, could you please re-post there?

On Tue, Sep 6, 2011 at 4:10 PM, John Wieczorek <tuco at berkeley.edu> wrote:
> Excellent. We are in good company then in trying to resolve this issue.
> On Tue, Sep 6, 2011 at 4:08 PM, Hilmar Lapp <hlapp at nescent.org> wrote:
>> Where is adopting these terms now going to put us with respect to OGC
>> standards, which, I think, will ultimately be more authoritative than an
>> informal W3C vocabulary.
>> I don't have enough insight into OGC standards for vocabularies for
>> describing geolocations, but I have also learned earlier this year from Flip
>> Dibner (copied here) that there are efforts underway within OGC to create
>> RDF vocabularies (presumably corresponding to OGC's XML standards?).
>>        -hilmar
>> On Sep 6, 2011, at 6:33 PM, Javier de la Torre wrote:
>>> 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.
>>> Best,
>>> Javier.
>>> 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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>> --
>> ===========================================================
>> : Hilmar Lapp  -:- Durham, NC -:- informatics.nescent.org :
>> ===========================================================

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