Let me add, however, that there are very few contributors of data who would be able to make the transformation between spatial reference systems. Could you? It's not trivial. Therefore I think it far preferable for contributors to publish what they know with confidence, including "datum unknown". Let services make the transformations while leaving the original untouched.
On Tue, Jul 21, 2009 at 5:11 AM, Paul Kirkp.kirk@cabi.org wrote:
and it appears NASA still hasn't learnt it's lesson ...
http://www.newscientist.com/article/dn17350-nasa-criticised-for-sticking-to-...
Paul ________________________________ From: tdwg-tag-bounces@lists.tdwg.org [mailto:tdwg-tag-bounces@lists.tdwg.org] On Behalf Of Peter DeVries Sent: 21 July 2009 12:56 To: Bob Morris Cc: Technical Architecture Group mailing list; tdwg-geospatial@lists.tdwg.org Subject: Re: [tdwg-tag] Fwd: [Tc] Geo URI proposal in draft stage in the IETF
Hi Bob, You make several good points and I hope that this moves forward. I am less thrilled about not standardizing on WGS84. We have agreed to use metric and other standards and I think that data expressed using other Datum's will be largely misinterpreted. Arthur Chapman has convinced me that it may be impossible to get users to upload their GPS data in WGS84, but I think that it would be best if GBIF and others converted the data in regional Datum's into WGS84 and exposed it as WGS84. Encouraging the use of regional Datum's instead of WGS84 will likely lead to a number of scientific mistakes. I am sure your are familiar with these stories, but others on the list may not.
Math error equals loss of Mars orbiter
http://findarticles.com/p/articles/mi_m1200/is_15_156/ai_57155808/
NASA reported Sept. 30 that it had lost the $125 million Mars Climate Orbiter because the force exerted by the orbiter's thrusters remained in the system of units based on pounds and feet rather than being converted to metric. ... In 1985, he notes, controllers calculated distance in feet rather than nautical miles and inadvertantly pointed a mirror on the space shuttle Discovery away from Earth instead of toward a laser on Hawaii's Mauna Kea.
- Pete
On Fri, Jul 17, 2009 at 9:32 PM, Bob Morris morris.bob@gmail.com wrote:
I would say its concern is somewhat narrower than the illustrations in Bricklin's http://www.w3.org/2003/01/geo/
The IETF document is a draft proposal to have "geo" be an IANA registered URI scheme. (See http://en.wikipedia.org/wiki/URI_scheme) whereas the w3 Bricklin stuff is an informal (as you observe) vocabulary.
Were the IETF docment be accepted in its proposed draft form, the expression "geo:51.47026,-2.59466" would be a URI and so in RDF/XML one might see expressions like
<based_near rdf:about="geo:51.47026,-2.59466"/>
for the example from the Bricklin document's element
<based_near geo:lat="51.47026" geo:long="-2.59466"/>
All of that would support RDF semantic reasoning. For example, it would support the ability to axiomatize something like "If point p is in feature f, and if feature f is_near point q, then point p is_near point q".
But in RDF you can't talk about resources that don't have a URI, so the IETF proposal would make it possible for geographic entities to be RDF resources. Most importantly, this would happen in such a way that one can tell when two geographic resources are the same. For example, the comparison definition in the IETF proposal specifies http://www.w3.org/2005/Incubator/geo/XGR-geo-20071023/#owl that two points are the same if their coordinates (and a few other things) are mathematically the same. Thus, slightly oversimplified, geo:51.47026,-2.59466 and geo:51.470260,-2.59466 (note trailing 0 in lat) always designate the same resource, which is something one can only wish for in the nascent vocabulary semi-proposal, widely adopted despite Bricklin's warning that it is not in the W3C recommendation track.
In summary, the IETF proposal would elevate at least points to the status of entities in their own right, as opposed to "merely" properties of some other entity.
http://www.w3.org/2005/Incubator/geo/XGR-geo-20071023/ goes a little farther than the Bricklin document, and identifies a need to update that document. It also provides an OWL model of the main elements of GML:
"Geo OWL provides an ontology which closely matches the GeoRSS feature model and which utilizes the existing GeoRSS vocabulary for geographic properties and classes. The practical consequence is that fragments of GeoRSS XML within RSS 1.0 or Atom which conform to the GeoRSS specification will also conform to the Geo OWL ontology (front-matter aside). Thus, the ontology provides a compatible extension of GeoRSS practice for use in more general RDF contexts."--http://www.w3.org/2005/Incubator/geo/XGR-geo-20071023/#owl
So the IETF proposal should be welcome as helping uniform application of Geo OWL, should it ever make it into the W3 recommendation process. Maybe Flip Dibner knows what the status of Geo OWL is.
--Bob Morris
On Fri, Jul 17, 2009 at 7:44 PM, Peter DeVries pete.devries@gmail.com wrote:
This appears to be a more formalized version of the current w3C geo: standard. Which people should also be familiar with since it is widely used. http://www.w3.org/2003/01/geo/
- Pete
On Mon, Jul 6, 2009 at 1:01 PM, Bob Morris morris.bob@gmail.com wrote:
TDWG should track this and consider requiring/recommending its use if it is accepted by IETF Bob Morris
---------- Forwarded message ---------- From: creed@opengeospatial.org Date: Mon, Jul 6, 2009 at 11:55 AM Subject: [Tc] Geo URI proposal in draft stage in the IETF To: tc@lists.opengeospatial.org
There is an internet draft that may be of interest to the OGC. I have provided some review and comments but the authors are seeking additional feedback. Feel free to contact the authors directly. There are GML examples in the document.
http://tools.ietf.org/id/draft-ietf-geopriv-geo-uri-01.txt
This document specifies an Uniform Resource Identifier (URI) for geographic locations using the 'geo' scheme name. A 'geo' URI identifies a physical location in a two- or three-dimensional coordinate reference system in a compact, simple, human-readable, and protocol independent way. The default coordinate reference system used is WGS-84.
Cheers
Carl
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-- Robert A. Morris Professor of Computer Science UMASS-Boston ram@cs.umb.edu http://bdei.cs.umb.edu/ http://www.cs.umb.edu/~ram http://www.cs.umb.edu/~ram/calendar.html phone (+1)617 287 6466
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Pete DeVries Department of Entomology University of Wisconsin - Madison 445 Russell Laboratories 1630 Linden Drive Madison, WI 53706
-- Robert A. Morris Professor of Computer Science UMASS-Boston ram@cs.umb.edu http://bdei.cs.umb.edu/ http://www.cs.umb.edu/~ram http://www.cs.umb.edu/~ram/calendar.html phone (+1)617 287 6466
--
Pete DeVries Department of Entomology University of Wisconsin - Madison 445 Russell Laboratories 1630 Linden Drive Madison, WI 53706
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