RE: Issue 27: correction of the description of the Coverage in Linked Data deliverable

I would think that QB[1] (which is derived from SDMX) would have something to contribute here. It is an RDF vocabulary that describes the structure of a datacube, and this provides specific RDF-oriented queries into cells, slices, dimensions of gridded data. Geospatial coverages have the additional feature that one or more of the dimensions is spatio-temporal.

My view is that there should be no expectation that whole datasets would have to be transformed and stored following QB, but that subsets can be uniquely identified using QB-bases queries, which would then be transformed into the native query (WCS, SOS, OPeNDAP) and passed on to the hosting service).

[1] http://www.w3.org/TR/vocab-data-cube/


From: Peter Baumann [mailto:p.baumann@jacobs-university.de]
Sent: Monday, 12 October 2015 8:29 AM
To: Jon Blower <j.d.blower@reading.ac.uk>
Cc: Ed Parsons <eparsons@google.com>; Cox, Simon (L&W, Clayton) <Simon.Cox@csiro.au>; frans.knibbe@geodan.nl; public-sdw-wg@w3.org
Subject: Re: Issue 27: correction of the description of the Coverage in Linked Data deliverable

Hi Jon,

exciting questions indeed, you are absolutely right: large portions of the overall issue are independent from "to coverage or not to coverage" (sorry for bending language).
What I find particularly interesting is this transition from general data linking into referencing the internals of an object. A coverage is just one particular case, so solving this might open up vistas for other links - into graphs, into documents (I mean: more than just HTML anchors), etc. This is one reason why I am curiously following progress in this group.

Nite,
Peter

On 2015-10-11 21:06, Jon Blower wrote:
Hi Peter,

I’m not suggesting redefining “coverage”, I’m suggesting that there are interesting questions around the use of coverages in the Linked Data world that aren’t concerned with ISO19123, for example:

1. Identifying coverages (hence being able to link to them).
2. Behaviour of web services that serve coverages (e.g. how can we improve WCS, OPeNDAP, NcSS etc to play more nicely with the wider web?).
3. Linking between data catalogues and coverage services (e.g. linking between GeoDCAT descriptions and concrete data access services)

None of these are within scope for ISO19123, but I believe are interesting problems that this group could help with (and are on my mind at the moment because we need solutions for the MELODIES project).

The question of linking *into* coverages (i.e. identifying coverage subsets) probably does involve stuff like ISO19123(-2), because for that we do need some common understanding of what a coverage data structure looks like.

By leaping immediately into the ISO19123 world we restrict ourselves unnecessarily to the problem of modelling and encoding coverages, which is certainly relevant but not the only problem that’s pertinent to Linked Data (particularly since there are many other groups covering* some of this).

Cheers,
Jon

* no pun intended


On 11 Oct 2015, at 19:29, Peter Baumann <p.baumann@jacobs-university.de<mailto:p.baumann@jacobs-university.de>> wrote:

Hi Jon-

several case studies for a range of different areas have been conducted, here a theoretical [1] and an applied one [2] - these are just a few, of course, others have worked on this, too. It is just that the term "coverage" has a particular definition, so we cannot redefine at will if interoperability is among the goals. A clear scientific treatment of terms seems important. Hence, for scientific groundwork I'd suggest to use a neutral term, maybe "pictures" or anything else that appears meaningful and not yet taken.

cheers,
Peter

[1]  Angelica Garcia, Peter Baumann: Modeling Fundamental Geo-Raster Operations with Array Algebra. IEEE international workshop in spatial and spatio-temporal data mining, October 28-31 2007, Omaha, USA
[2] Peter Baumann, Maximilian Höfner, Walter Schatz: Querying Large Geo Image Databases: A Case Study. IV Brazilian Symposium on GeoInformatics - GeoInfo 2002, December 5-6 2002, Caxambu, Brazil

(BTW, similar studies have been done for astro and life sciences, too)
On 2015-10-10 20:31, Jon Blower wrote:
Hi all,

I’m relatively new to this group so I don’t know all the history behind the wording of the Charter but I have always found this particular requirement to be prematurely specific. Personally I would be more comfortable with a requirement along the lines of (in imprecise language), “We know that a lot of coverage data are being published and such data pose challenges for Linked Data approaches. This group will develop recommendations for making best use of coverage data in a Linked Data environment.”

From this high-level requirement we need to develop specific use cases that identify real gaps in the ecosystem and work out what we can actually do to fill them, within the scope of this group (and what we defer to other groups). I don’t think I’ve seen this level of analysis so far (apologies if I’ve missed something) but I’d be keen to participate in such an activity.

Personally I don’t see a need to mention ISO19123, WaterML2, NetCDF or any other specific standard at the level of this requirement, except perhaps to give examples of what a coverage is. The following sentence in the Charter does a good job of highlighting that we will look at prior art:

"Where deliverables build on prior work, any variance developed by the Spatial Data on the Web WG will be backwards compatible with the existing work. The aim is to formalize existing work, not to replace or compete with it.”

Just my 0.013p (at current exchange rates).

Jon




On 10 Oct 2015, at 18:44, Ed Parsons <eparsons@google.com<mailto:eparsons@google.com>> wrote:

So would a better approach be to have less specificity in the requirement?
Ed

On Sat, 10 Oct 2015, 11:41 Peter Baumann <p.baumann@jacobs-university.de<mailto:p.baumann@jacobs-university.de>> wrote:
yes, indeed ISO will take its time. Once there, ISO CIS will stay for many years as ISO's understanding of coverages.
It will be a core decision for the SDW WG whether to bypass ISO and INSPIRE and establish a silo solution, or be compatible with the mainstream.


-Peter


On 2015-10-10 08:13, Simon.Cox@csiro.au<mailto:Simon.Cox@csiro.au> wrote:
>  ISO-19123-2 (the soon to be published ISO version of the OGC Coverage Implementation Schema 1.1)?

‘soon to be published’ is optimistic.
It is not yet on the ISO/TC 211 program of work [1].
The duration from NWIP (New Work Item Proposal) to IS (International Standard) is never less than 3 years, even if there is a mature starting document.

[1] http://www.isotc211.org/pow.htm


From: Frans Knibbe [mailto:frans.knibbe@geodan.nl]
Sent: Friday, 9 October 2015 11:28 PM
To: SDW WG Public List <public-sdw-wg@w3.org><mailto:public-sdw-wg@w3.org>; Peter Baumann <p.baumann@jacobs-university.de><mailto:p.baumann@jacobs-university.de>
Subject: Issue 27: correction of the description of the Coverage in Linked Data deliverable

Issue 27<http://www.w3.org/2015/spatial/track/issues/27> is a special one, because it is about one of the deliverables. The Coverage in Linked Data deliverable<http://www.w3.org/2015/spatial/charter#cov> reads "The WG will develop a formal Recommendation for expressing discrete coverage data conformant to the ISO 19123 abstract model. ..."

Peter explained that this statement probably requires some adjustment, see this message<https://lists.w3.org/Archives/Public/public-sdw-wg/2015Apr/0024.html>, otherwise the deliverable will not have the proper foundation.

Do I understand correctly that is is a matter of saying that the Recommendation will not be based on ISO-19123, but on ISO-19123-2 (the soon to be published ISO version of the OGC Coverage Implementation Schema 1.1)?

We can not change the charter text, but we could add a clarification (a note) in the chapter about deliverables in the UCR document (Ed, Kerry or Phil: is that correct?).

If the assumption above are correct, could someone suggest a good wording for the note that should be added?

Regards,
Frans


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--

Dr. Peter Baumann

 - Professor of Computer Science, Jacobs University Bremen

   www.faculty.jacobs-university.de/pbaumann<http://www.faculty.jacobs-university.de/pbaumann>

   mail: p.baumann@jacobs-university.de<mailto:p.baumann@jacobs-university.de>

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 - Executive Director, rasdaman GmbH Bremen (HRB 26793)

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   tel: 0800-rasdaman, fax: 0800-rasdafax, mobile: +49-173-5837882

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--

Dr. Peter Baumann

 - Professor of Computer Science, Jacobs University Bremen

   www.faculty.jacobs-university.de/pbaumann<http://www.faculty.jacobs-university.de/pbaumann>

   mail: p.baumann@jacobs-university.de<mailto:p.baumann@jacobs-university.de>

   tel: +49-421-200-3178, fax: +49-421-200-493178

 - Executive Director, rasdaman GmbH Bremen (HRB 26793)

   www.rasdaman.com<http://www.rasdaman.com>, mail: baumann@rasdaman.com<mailto:baumann@rasdaman.com>

   tel: 0800-rasdaman, fax: 0800-rasdafax, mobile: +49-173-5837882

"Si forte in alienas manus oberraverit hec peregrina epistola incertis ventis dimissa, sed Deo commendata, precamur ut ei reddatur cui soli destinata, nec preripiat quisquam non sibi parata." (mail disclaimer, AD 1083)