[tdwg-content] Easting and northing
Markus Döring
mdoering at gbif.org
Wed Feb 11 13:17:48 CET 2015
Hi,
this suspicous flag in GBIF is raised for occurrences when our reprojection to WGS84 causes a suspicous large coordinate shift:
"Indicates successful coordinate reprojection according to provided datum, but which results in a datum shift larger than 0.1 decimal degrees.”
In those case we keep the original coordinates. We also ignore the verbatim values as there are valid lat/lon values in the record. We only try to interpret the verbatim ones if the regular lat/lon values do not exist.
In this specific case it is odd as the datum EPSG:3857 is the WGS84 Web Mercator projection which should not cause any change I believe?
http://spatialreference.org/ref/sr-org/7483/
This might boil down to a question I had with permitted values for dwc:geodeticDatum. The name suggests strictly a datum, but the definition and actual values found in there are mixing full reference systems, datums and any other identifyable spatial systems.
The current definition is: "The ellipsoid, geodetic datum, or spatial reference system (SRS) upon which the geographic coordinates given in decimalLatitude and decimalLongitude as based"
Most of the codes (often epsg) we find in GBIF occurrences represent full reference systems with a geoid, meridian, unit, projection and not just a datum. We do interpret the given coordinate in that case with the entire system, not just the datum. In case it is just a datum, we interpret coordinates with a default geodetic ellipsoid using the greeenwich meridian (DefaultEllipsoidalCS.GEODETIC_2D in geotools).
best,
Markus
On 10 Feb 2015, at 15:14, John Wieczorek <tuco at berkeley.edu> wrote:
> That looks great to me. What kind of a 'suspicious' notice do you get?
>
> On Tue, Feb 10, 2015 at 6:59 AM, Quentin Groom <quentin.groom at br.fgov.be> wrote:
> Here is an example of DwC where I think I'm correct, but GBIF considered my verbatim data "suspicious". Plant recording in Britain is conducted in grid squares of the Ordanace Survey. Those coordinates have a very specific notation so that my verbatimCoordinatesare some thing like this NZ3767 and my verbatimCoordinateSystem is OSGB36 (e.g. http://www.gbif.org/occurrence/1020049283/verbatim). To me this is correct usage of the verbatim fields. I do complete the decimal longitude and latitude fields, based upon the centre of the square, but as these are based on the point-radius view of observations they are largely useless for real analysis.
> To make my records internationally acceptable I also complete the footprintWKT and footprintSRS, but although this is probably the best description of the locality I'm fairly sure that nobody will actually use it.
> Quentin
>
> Roderic Page wrote:
> Is it wrong that I’d be happier if Darwin Core itself had terms for easting, northing, and zones so there was no ambiguity (or at least it would be minimised). Putting stuff in text fields and hoping people can figure it out is just asking for trouble, as is overloading fields.
>
> If they do go into verbatimCoordinates, I wonder if the spec/examples could add a regular expression to they would have to pass in order to be accepted.
>
> Regards
>
> Rod
>
> ---------------------------------------------------------
> Roderic Page
> Professor of Taxonomy
> Institute of Biodiversity, Animal Health and Comparative Medicine
> College of Medical, Veterinary and Life Sciences
> Graham Kerr Building
> University of Glasgow
> Glasgow G12 8QQ, UK
>
> Email: Roderic.Page at glasgow.ac.uk <mailto:Roderic.Page at glasgow.ac.uk>
> Tel: +44 141 330 4778
> Skype: rdmpage
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> ORCID: http://orcid.org/0000-0002-7101-9767
> Citations: http://scholar.google.co.uk/citations?hl=en&user=4Z5WABAAAAAJ <http://scholar.google.co.uk/citations?hl=en&user=4Z5WABAAAAAJ>
> ResearchGate https://www.researchgate.net/profile/Roderic_Page
>
>
> On 9 Feb 2015, at 17:03, Markus Döring <m.doering at mac.com <mailto:m.doering at mac.com>> wrote:
>
> Hi Rod & John,
>
> for the future documentation of dwc I’d be curious if we all think it is a good idea to overload verbatimLongitude/Latitude with not strictly lon/lat values like easting and northing.
> I *think* I would prefer a definition, comment and examples where UTM values go into the verbatimCoordinates field only, even though it would be great to not have to parse them out from a string.
> Any strong opinions?
>
>
> On 09 Feb 2015, at 17:25, Roderic Page <Roderic.Page at glasgow.ac.uk <mailto:Roderic.Page at glasgow.ac.uk>> wrote:
>
> Hi John,
>
> I guess my concern is that the TTU dataset in VertNet/GBIF didn’t explicitly say that the verbatimLatitude/Longitude were easting and northings (other values it has in those fields for other records are lats and longs), nor did it include the zone information, or the fact that the values were for south of the equator (TTU itself doesn’t say that either). I had to go back to the TTU web site to discover that.
>
> So, even if parsing is a mess (and I agree it pretty much always is) the TTU output didn’t have everything needed to figure out how to parse the data correctly. It would be nice if the data that gets to the aggregator is complete enough to be interepreted, leaving aside in what fields people stick that information.
>
> Regards
>
> Rod
>
> ---------------------------------------------------------
> Roderic Page
> Professor of Taxonomy
> Institute of Biodiversity, Animal Health and Comparative Medicine
> College of Medical, Veterinary and Life Sciences
> Graham Kerr Building
> University of Glasgow
> Glasgow G12 8QQ, UK
>
> Email: Roderic.Page at glasgow.ac.uk <mailto:Roderic.Page at glasgow.ac.uk>
> Tel: +44 141 330 4778
> Skype: rdmpage
> Facebook: http://www.facebook.com/rdmpage
> LinkedIn: http://uk.linkedin.com/in/rdmpage
> Twitter: http://twitter.com/rdmpage
> Blog: http://iphylo.blogspot.com
> ORCID: http://orcid.org/0000-0002-7101-9767
> Citations: http://scholar.google.co.uk/citations?hl=en&user=4Z5WABAAAAAJ <http://scholar.google.co.uk/citations?hl=en&user=4Z5WABAAAAAJ>
> ResearchGate https://www.researchgate.net/profile/Roderic_Page
>
>
> On 9 Feb 2015, at 16:12, John Wieczorek <tuco at berkeley.edu <mailto:tuco at berkeley.edu>> wrote:
>
> Hi Rod,
>
> I would treat easting and northing as latitude and longitude, but not following strictly the definition in Darwin Core. There is actually value in being able to have the easting (longitude) separate from the northing (latitude) if the source has them separated. It makes it that much less ambiguous to interpret. I would also have that full tuple as in the example you gave (18M 166624 9840350) along with "UTM" in verbatimCoordinateSystem, and a datum or something similar in verbatimSRS. We want more information, not less, when it comes time to try to turn this all into more readily usable information (decimalLatitude, decimalLongitude, geodeticDatum, coordinateUncertaintyInMeters). All of this verbatim separation arose from the heyday of massive collaborative georeferencing in MaNIS, HerpNET, and ORNIS where we were able to take good advantage of whatever information the source had, and that is why verbatimCoordinateSystem is part of the offerings, to help with tha parsing problem if the original source is known.
>
> In short, I wouldn't have it any other way than the way it is done with TTU. It actually allows use to extract more information correctly rather than less. Parsing is a mess, but it is a mess anyway. It takes me about 25 steps to parse the variations I see in verbatim coordinates in VertNet. but it is worth it.
>
> Now, to get back to TTU and upgrade their venerable migrator and see how things look afterwords. We appreciate the careful eye and the quality feedback reports to Github on TTU's behalf.
>
> Cheers,
>
> John
>
>
> On Mon, Feb 9, 2015 at 8:50 AM, Roderic Page <Roderic.Page at glasgow.ac.uk <mailto:Roderic.Page at glasgow.ac.uk>> wrote:
>
> Hi Dag,
>
> Gack, this is where things get messy. I wouldn’t treat easting
> and northing as latitude and longitude (although they are
> obviously related). When I write code to parse verbatim
> latitude and longitude the last thing I expect is easting and
> northing (it’s hard enough already given the various ways
> people write lats and longs). There seems to be enough
> ambiguity here to really mess things up, as indeed they have
> for the TTU dataset.
>
> Regards
>
> Rod
>
> ---------------------------------------------------------
> Roderic Page
> Professor of Taxonomy
> Institute of Biodiversity, Animal Health and Comparative Medicine
> College of Medical, Veterinary and Life Sciences
> Graham Kerr Building
> University of Glasgow
> Glasgow G12 8QQ, UK
>
> Email: Roderic.Page at glasgow.ac.uk
> <mailto:Roderic.Page at glasgow.ac.uk>
> Tel: +44 141 330 4778 <tel:%2B44%20141%20330%204778>
> Skype: rdmpage
> Facebook: http://www.facebook.com/rdmpage
> LinkedIn: http://uk.linkedin.com/in/rdmpage
> Twitter: http://twitter.com/rdmpage
> Blog: http://iphylo.blogspot.com <http://iphylo.blogspot.com/>
> ORCID: http://orcid.org/0000-0002-7101-9767
> Citations: http://scholar.google.co.uk/citations?hl=en&user=4Z5WABAAAAAJ
> <http://scholar.google.co.uk/citations?hl=en&user=4Z5WABAAAAAJ>
> ResearchGate https://www.researchgate.net/profile/Roderic_Page
>
>
> On 9 Feb 2015, at 11:41, Dag Endresen <dag.endresen at gmail.com
> <mailto:dag.endresen at gmail.com>> wrote:
>
> Hi Rod,
>
> I have assumed that the purpose of the dwc:verbatimCoordinates
> term is
> to allow for reporting coordinates originally recorded as one
> single
> tuple such as the MGRS (Military Grid Reference System).
>
> While original source coordinates that do have two tuples such
> as UTM
> would use dwc:verbatimLongitude (for the Easting or X coordinate
> tuple) and dwc:verbatimLatitude (for the Northing or Y coordinate
> tuple).
>
> Regards
> Dag
>
>
> On 9 February 2015 at 11:57, Roderic Page
> <Roderic.Page at glasgow.ac.uk
> <mailto:Roderic.Page at glasgow.ac.uk>> wrote:
> Hi John,
>
> So, if I understand you correctly, you would have hoped that
> TTU would have
> output something like this:
>
> “dwc:verbatimCoordinates” : “18M 166624 9840350”
>
> rather than put the easting and northing into
> verbatimLatitude and
> verbatimLongitude.
>
> Regards
>
> Rod
>
> ---------------------------------------------------------
> Roderic Page
> Professor of Taxonomy
> Institute of Biodiversity, Animal Health and Comparative Medicine
> College of Medical, Veterinary and Life Sciences
> Graham Kerr Building
> University of Glasgow
> Glasgow G12 8QQ, UK
>
> Email: Roderic.Page at glasgow.ac.uk
> <mailto:Roderic.Page at glasgow.ac.uk>
> Tel: +44 141 330 4778 <tel:%2B44%20141%20330%204778>
> Skype: rdmpage
> Facebook: http://www.facebook.com/rdmpage
> LinkedIn: http://uk.linkedin.com/in/rdmpage
> Twitter: http://twitter.com/rdmpage
> Blog: http://iphylo.blogspot.com <http://iphylo.blogspot.com/>
> ORCID: http://orcid.org/0000-0002-7101-9767
> Citations:
> http://scholar.google.co.uk/citations?hl=en&user=4Z5WABAAAAAJ
> <http://scholar.google.co.uk/citations?hl=en&user=4Z5WABAAAAAJ>
> ResearchGate https://www.researchgate.net/profile/Roderic_Page
>
>
> On 8 Feb 2015, at 20:22, John Wieczorek <tuco at berkeley.edu
> <mailto:tuco at berkeley.edu>> wrote:
>
> Hi Rod,
>
> The verbatimLatitude, verbatimLongitude, and
> verbatimCoordinates were all
> intended to be able to capture the original coordinates used
> at the source,
> where decimalLatitude and decimalLongitude, with
> geodeticDatum, were meant
> to contain the the easy to act on global system (UTMs do not
> cover the
> entire planet, for example). The verbatimCoordinate term's
> definition shows
> that this was the intent, but verbatimLatitude and
> verbatimLongitude do not.
> When we get the examples separated from the term definitions,
> it should be
> easier to make this clear.
>
> Cheers,
>
> John
>
> On Sat, Feb 7, 2015 at 2:36 PM, Dag Endresen
> <dag.endresen at gmail.com <mailto:dag.endresen at gmail.com>> wrote:
>
> Hi Rod,
>
> At least in Norway, it is very common for the GBIF node to
> receive
> (only) Easting and Northing of UTM zones 32V to 36W. For
> many datasets
> we will on routine automatically make the conversion to decimal
> degrees (and WGS84) at the node before these datasets are
> published to
> the GBIF portal. When people download occurrences from the
> Norwegian
> "GBIF portal", Artskart, my impression is that the UTM 32V
> (and the
> 33V) Easting and Northing coordinate format is actually more
> popular
> than the decimal degree format - this is because the
> geographic data
> layers for Norway more often are made available in the UTM
> format
> (most often 32V or 33V) [1]. And yes, this continued present day
> official use of such a wide variety of coordinate formats
> frustrates
> me too... The historic use reported with the verbatim terms,
> is of
> course difficult to do anything with...
>
> I assume that Easting and Northing coordinates are both
> valid and very
> common values (and not only in Norway) for the Darwin Core
> verbatim
> coordinate terms (dwc:verbatimLatitude and
> dwc:verbatimLongitude or
> dwc:verbatimCoordinates), but of course only at all useful when
> accompanied by the respective dwc:verbatimCoordinateSystem and
> dwc:verbatimSRS also reported. (And that the
> dwc:decimalLatitude and
> dwc:decimalLongitude correctly reported in WGS84 should
> preferably
> also always be there). I believe that Darwin Core is already
> fine with
> respect to terms to report geographic coordinates. If at all any
> additions are useful, I believe that identifying and
> recommending
> terms from more specialized geographic vocabularies and
> ontologies
> might be much more useful than adding any new dwc:Location
> terms to
> Darwin Core. In fact, most of the dwc:Location terms might
> perhaps
> preferably be replaced by terms from the geography
> community... such
> as perhaps [2] and [3] (as a start).
>
> [1]
> https://dagendresen.wordpress.com/2013/11/22/convert-coordinate-srs/
> [2] http://www.w3.org/2003/01/geo/wgs84_pos#
> [3] http://www.geonames.org/ontology/documentation.html
>
> Regards
> Dag
>
>
> On 7 February 2015 at 13:02, Roderic Page
> <Roderic.Page at glasgow.ac.uk <mailto:Roderic.Page at glasgow.ac.uk>>
>
> wrote:
> Pardon my ignorance, but has there ever been a discussion
> of easting and
> northing values in regards to Darwin Core? AFAIK the
> current standard
> doesn’t mention them. The reason I’m asking is that I’ve
> just come
> across
> some VerbatimLatitude and VerbatimLongitude values in a
> dataset that is
> aggregated by VertNet (and hence GBIF) where (after some head
> scratching) I
> realised that the verbatim values were actually Easting and
> Northing
> (which
> I didn’t know existed until yesterday). Details are here:
> https://github.com/ttu-vertnet/ttu-mammals/issues/11
>
> I’m guessing this isn’t a terribly common way to record
> location
> information, but it looks like in this case the lack of
> support for this
> type of data has resulted in somebody trying to shoehorn
> them into
> VerbatimLatitude and VerbatimLongitude, resulting in values
> which are
> uninterpretable to aggregators further up the chain.
>
> Regards
>
> Rod
>
>
>
> --
> Dag Endresen, Ph.D.
> Private email: dag.endresen at gmail.com
> <mailto:dag.endresen at gmail.com>
> Work email: dag.endresen at nhm.uio.no
> <mailto:dag.endresen at nhm.uio.no>
> Mobile: +47 4061 2982
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>
>
> -- Dag Endresen, Ph.D.
> Private email: dag.endresen at gmail.com
> <mailto:dag.endresen at gmail.com>
> Work email: dag.endresen at nhm.uio.no
> <mailto:dag.endresen at nhm.uio.no>
> Mobile: +47 4061 2982
>
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> Dr. Quentin Groom
> (Botany and Information Technology)
>
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