Comments/questions inline

Peter DeVries wrote:
Hi Steve,

This is mainly and advantage if everyone supports the ietf.org proposal in the way they support the geo vocabulary.
Well, up to this point, I've seen people using the geo: vocabularly as it was described in http://www.w3.org/2003/01/geo/ , i.e. as an RDF predicate to define string literal property elements.  The use as you've described it is new to me.

The way to think about this is ietf geo could become a well unknown URN.
Speaking completely out of ignorance, are there any LOD applications that know how to interpret URIs that aren't HTTP URIs?  I mean, if you have RDF that has something like geo:41.53000000,-70.67000000 as an object, is there any application that "understands" it?  I learned in the last few months that it's "legal" to have an LSID as an object in an RDF triple, but that doesn't mean that any application will know what to do with it. 
......

Note that your use of geo is not standard DarwinCore. What is the official word from the DarwinCore Illuminati on the use of geo?
Well there was a proposal on the table for including geo:lat, geo:long in the Darwin Core standard.  As far as I know, there hasn't been any movement on that proposal (haven't checked recently).  But I really don't feel compelled to use Darwin Core exclusively in RDF that I write.  If a vocabulary like FOAF is more "well-known" for describing people, I don't think there is any reason not to use it.  I think at this point, geo:lat is more well-known than dwc:decimalLatitude (plus specifying the dwc:geodedicDatum isn't required with geo: since WGS84 is assumed). 

Thanks for the comments,
Steve

I am sympathetic to the need for some measure of radius, pointSpatialFit,  coordinateUncertaintyInMeters etc. but adoption of these has been poor.

I think the "radius" and area form that I am proposing is easy for providers to understand and for tools to interpret.

It probably maps to dwc:coordinateUncertaintyInMeters

Here is a modification of your earlier location example using a TDWG BioBlitz record. Note how I replace some standard vocabulary terms with URI's.

Those things with txn, could be incorporated in to the DarwinCore.

<!-- The who, what, where and when and how of the observation, as efficient as I can make it but with a literal for scientific name (label) -->

<dwc:Occurrence about="http://www.cs.umbc.edu/~jsachs/occurrences/tdwg2010bioblitz_1607">
    <rdfs:label>OBS: Branta canadensis</rdfs:label>
    <dwc:Area resource="geo:41.53000000,-70.67000000;u=100">
    <txn:occurrenceHasSpeciesConcept rdf:resource="http://lod.taxonconcept.org/ses/SeecQ#Species"/>
    <txn::hasCollector rdf:resource="http://lod.taxonconcept.org/people/tdwg2010bioblitz#Dmitry_Mozzherin"/>
    <txn::occurrenceHasIndividual rdf:resource="http://www.cs.umbc.edu/~jsachs/individuals/tdwg2010bioblitz_1607"/>
    <foaf:depiction rdf:resource="http://farm5.static.flickr.com/4126/5037315500_4c555f742a_b.jpg"/>
    <txn:basisOfRecord rdf:resource="http://lod.taxonconcept.org/ontology/txn.owl#BasisOfRecord_StillImage"/>
    <dcterms:date>2010-09-29</dcterms:date>
</dwc:Occurrence>

<!-- The area is is a Location and the georeference method is included as metadata. wdrs is used to link the area to the RDF. -->
<!-- I will change the Area ontology so that it is a subclass of dcterms:Location -->
<!-- If others make statements about this particular area, their RDF's wdrs will create the provenence links -->

<dwc:Area about="geo:41.53000000,-70.67000000;u=100">
    <rdf:type resource="http://purl.org/dc/terms/Location"/>
    <dwc:georeferenceMethod  resource="http://rs.tdwg.org/dwc/terms/index.htm#GeoMethod_GoogleMaps">
    <dwc_area:areaWithInFeature rdf:resource="http://sws.geonames.org/4929772/"/>
    <wdrs:describedby rdf:resource="http://my_organization.com/occurrence/123.rdf"/>
</dwc:Area>

<!-- Like the occurrence the individual is only one thing but different people make assertions about what that thing is -->

<dwc:Individual about="http://www.cs.umbc.edu/~jsachs/individuals/tdwg2010bioblitz_1607">
    <rdfs:label>IND_1607: Branta canadensis</rdfs:label>
    <txn:occurrenceHasSpeciesConcept rdf:resource="http://lod.taxonconcept.org/ses/SeecQ#Species"/>
    <txn::hasCollector rdf:resource="http://lod.taxonconcept.org/people/tdwg2010bioblitz#Dmitry_Mozzherin"/>
    <txn::individualHasOccurrence rdf:resource="http://www.cs.umbc.edu/~jsachs/occurrences/tdwg2010bioblitz_1607"/>
    <foaf:depiction rdf:resource="http://farm5.static.flickr.com/4126/5037315500_4c555f742a_b.jpg"/>
    <!-- Identification history should be part of the documentation of the individual -->
    <txn:individualHasCurrrentIdentificationAssertion rdf:resource="http://www.cs.umbc.edu/~jsachs/identifications/tdwg2010bioblitz_1607_id_2"/>
    <txn:individualHasPreviousIdentificationAssertion rdf:resource="http://www.cs.umbc.edu/~jsachs/identifications/tdwg2010bioblitz_1607_id_1"/>
</dwc:Individual>

Respectfully,

- Pete

On Sun, Feb 27, 2011 at 6:55 AM, Steve Baskauf <steve.baskauf@vanderbilt.edu> wrote:
Pete,
This topic has come up several times before and each time I've left the email sitting in my inbox with the intention of trying to understand it better.  I guess what I don't understand is what one "does" with it.  I suppose I could dig in and do some research, but the multiple times the message has sat in my inbox without action tells me that I'm probably not going to get around to doing that.  So maybe you can explain it further. 

Is this supposed to be usable as a "Linked Data" resource (i.e. object of a predicate such as "hasLocation")?  It isn't an HTTP URI, so it can't get dereferenced via http.  I guess one parses it as a string and interprets the string directly based on some rules.  Isn't that a no-no in the GUID rules?  I guess with enough community support, applications would know what do do with it, but look what happened with "urn:lsid:my_organization.com:location:123".  Web browsers and "regular" Linked Data clients (e.g. Linked Data browsers) didn't know what to do with it.

The whole issue of provenance is pretty satisfactorily handled in the existing Darwin Core. There are a multitude of terms available to express all kinds of uncertainty and shapes.  For example, if I create a record like:

<rdf:Description about="http://my_organization.com/location/123">
    <rdf:type resource="http://purl.org/dc/terms/Location"/>
    <geo:lat>36.144719</geo:lat>
    <geo:long>-86.801498</geo:long>
    <dwc:coordinateUncertaintyInMeters>1000</dwc:coordinateUncertaintyInMeters>
    <dwc:georeferenceRemarks>Location determined from Google maps</dwc:georeferenceRemarks>
</rdf:Description>

I very explicitly express the type of thing, geocoordinates, datum (implicit in the use of geo:), uncertainty, and method of generating the data.  If necessary, I could also use dwc:dataGeneralizations and dwc:informationWithheld to explain how and why I have provided less precise coordinates than I actually know.  This is clearly more verbose, but hey, Linked data in xml IS verbose, and existing Linked Data applications would be able to "understand" something like what I wrote without any kind of special "plug-in" to interpret the spring.  I guess I don't really understand why you are proposing this, especially since you are a passionate advocate of Linked Data.  Your proposed thing is more succinct, but it doesn't seem like it would be usable by normal Linked Data clients.

Steve


Bob Morris wrote:
Your arguably reasonable recoding of the geo uri's of your example illustrates an issue on which so much metadata is silent: provenance. Once exposed, it is probably impossible for someone to know how the uncertainty (or any other data that might be the subject of opinion or estimate) was determined and whether the data is fit for some particular purpose, e.g. that the species were observed near each other. 

BTW, the IETF geo proposal was adopted in 2010, in the final form given at  http://tools.ietf.org/html/rfc5870 . One interesting point is  http://tools.ietf.org/html/rfc5870#section-3.4.3 which says 
  "Note: The number of digits of the values in <coordinates> MUST NOT be interpreted as an indication to the level of uncertainty." The section following is also interesting, albeit irrelevant for your procedure. It implies that when uncertainty is omitted (and therefore unknown), then "geo:41.53000000,-70.67000000"  and "geo:41.53,-70.67"  identify  the same geo resource.


Bob Morris

On Wed, Feb 23, 2011 at 4:56 PM, Peter DeVries <pete.devries@gmail.com> wrote:

[...]

5) I added in my proposed "area" so that it is easy to see what species were observed near each other. Since there was no measure of radius in these longitude and latitudes I made the radius 100 meters.
    Normally I would estimate the radius for a GPS reading to be within 10 meters but some of these observations were made where the GPS reading was taken and the readings were given only to two decimals.

Area = long, lat; radius in meters following the ietf proposal but with the precision of the long and lat standardized example "geo:41.53000000,-70.67000000;u=100"

[...]
--
Robert A. Morris
Emeritus Professor  of Computer Science
UMASS-Boston
100 Morrissey Blvd
Boston, MA 02125-3390
Associate, Harvard University Herbaria
email: morris.bob@gmail.com
web: http://efg.cs.umb.edu/
web: http://etaxonomy.org/mw/FilteredPush
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phone (+1) 857 222 7992 (mobile)


-- 
Steven J. Baskauf, Ph.D., Senior Lecturer
Vanderbilt University Dept. of Biological Sciences

postal mail address:
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delivery address:
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--
---------------------------------------------------------------
Pete DeVries
Department of Entomology
University of Wisconsin - Madison
445 Russell Laboratories
1630 Linden Drive
Madison, WI 53706
TaxonConcept Knowledge Base / GeoSpecies Knowledge Base
About the GeoSpecies Knowledge Base
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-- 
Steven J. Baskauf, Ph.D., Senior Lecturer
Vanderbilt University Dept. of Biological Sciences

postal mail address:
VU Station B 351634
Nashville, TN  37235-1634,  U.S.A.

delivery address:
2125 Stevenson Center
1161 21st Ave., S.
Nashville, TN 37235

office: 2128 Stevenson Center
phone: (615) 343-4582,  fax: (615) 343-6707
http://bioimages.vanderbilt.edu