W3C home > Mailing lists > Public > public-sdw-wg@w3.org > July 2016

RE: BP restructuring: Metadata section

From: Byron Cochrane <bcochrane@linz.govt.nz>
Date: Wed, 27 Jul 2016 13:01:41 +1200
To: 'Rob Atkinson' <rob@metalinkage.com.au>, 'Andrea Perego' <andrea.perego@jrc.ec.europa.eu>, 'Linda van den Brink' <l.vandenbrink@geonovum.nl>, "'SDW WG (public-sdw-wg@w3.org)'" <public-sdw-wg@w3.org>
Message-ID: <666FB8D75E95AE42965A0E76A5E5337E15D4E1731E@prdlsmmsg01.ad.linz.govt.nz>
Hi Rob,

I agree that capturing metadata in formats other than 19115 works fine, but I would be hesitant to call that best practice.
This is a best practices document.  Can’t we say capture in 19115 is current best practice for spatial metadata capture?  Doing so does not preclude other approaches – especially compatible ones.

Cheers,
Byron

From: Rob Atkinson [mailto:rob@metalinkage.com.au]
Sent: Wednesday, 27 July 2016 11:41 a.m.
To: Byron Cochrane; Andrea Perego; Linda van den Brink; SDW WG (public-sdw-wg@w3.org)
Subject: Re: BP restructuring: Metadata section

Hi Byron...

another way of looking at this is that different metadata has different degrees of expressivity - and the form closest to the actual creation processes of the data is usually the most detailed and accurate.

The implication is that ISO19115 is potentially a view of richer metadata itself - and/or a way of annotating it.  DCAT and RDf in general make attaching more detail relatively easy, and annotation of any component comes as a natural component.

So I'm not sure that a BP should be as prescriptive as "data creators and publishers capture metadata in ISO 19115" - rather that they capture metadata in a form that can be used to generate both ISO 19115 XML  and GeoDCAT RDF resources.  Capturing in ISO19115 works - but its not the only way.

Rob



On Wed, 27 Jul 2016 at 07:05 Byron Cochrane <bcochrane@linz.govt.nz<mailto:bcochrane@linz.govt.nz>> wrote:
Hi,

Jumping in here with  questions and comments about the role of 19115 in this.

Currently, the practice I am proposing here in NZ is that data creators and publishers capture metadata in ISO 19115 and publish GeoDCAT.  While GeoDCAT is great for search and discovery (two different things), it is only a subset of the 19115 standard.  For a more complete documentation of the dataset, ISO 19115 is still necessary.  But since 19115 is not (yet) linked data friendly, presentation in DCAT is a good best practice for publishing.

So I would suggest that the full best practice would be to capture metadata in ISO 19115 and present as GeoDCAT on the web.  This is the way that current GeoDCAT tools that I know of are designed to work.

Two further notions to throw out here, but not too sure how they fit.  Good metadata is first and foremost a tool that is necessary for good data management.  Search and discovery is secondary to this.  Also, I like to think of metadata, presented as HTML, as the natural landing page for datasets.  Not sure yet if the default landing page should be GeoDCAT or 19115.

Cheers,
Byron

-----Original Message-----
From: Andrea Perego [mailto:andrea.perego@jrc.ec.europa.eu<mailto:andrea.perego@jrc.ec.europa.eu>]
Sent: Wednesday, 27 July 2016 2:55 a.m.
To: Linda van den Brink; SDW WG (public-sdw-wg@w3.org<mailto:public-sdw-wg@w3.org>)
Subject: Re: BP restructuring: Metadata section

Thanks, Linda.

I would be happy to help here, also with examples.

Some preliminary comments on the listed types of spatial metadata:

 > data type (raster or vector)

Not sure if this completely matches with the ISO 19115 notion of "spatial representation type" - which is modelled with a code list including "grid", "vector", "text table", etc. - see:

https://geo-ide.noaa.gov/wiki/index.php?title=ISO_19115_and_19115-2_CodeList_Dictionaries#MD_SpatialRepresentationTypeCode


In any case, GeoDCAT-AP models this information by using adms:representationTechnique + URIs corresponding to the items in the ISO 19115 code list.

 > Coordinate Reference System(s)

I've already mentioned the approach used in GeoDCAT-AP:

https://lists.w3.org/Archives/Public/public-sdw-wg/2016May/0072.html


The "link" between data and the relevant CRS(s) is made with dct:conformsTo - which is also in line with the use of such property in DQV to express conformance with a "standard".

 > spatial resolution

As I said in another mail [1], DQV may offer a solution to this:

https://www.w3.org/TR/vocab-dqv/#ExpressDatasetAccuracyPrecision


The examples cover spatial resolution expressed as horizontal ground distance, equivalent scale, angular distance (which is how spatial resolution is expressed in ISO 19115 - we just miss an example on vertical distance).


About making "spatial *meta*data indexable", is this going under BP1 as well? I think we have already good examples to include, also showing how this is a feature that can be (more or less) easily integrated in existing geo catalogue services and tools.

On this specific topic, I take the opportunity to mention that we started a mapping exercise between DCAT-AP + GeoDCAT-AP and Schema.org:

https://webgate.ec.europa.eu/CITnet/stash/projects/ODCKAN/repos/dcat-ap-to-schema.org/


One of the preliminary results of this work is: do we really need to map everything? Besides the fact that Schema.org does not include terms to model all what is in DCAT-AP / GeoDCAT-AP, the use cases addressed by these metadata schemas are different. So, the question is: what is really needed to be mapped to Schema.org to enable Web indexing and discoverability?

I think this is a general design issue about enabling the re-use of spatial data (not only metadata), that, in my understanding, was shown pretty clearly in the Geonovum testbed, where only a "simplified"
version of spatial data and metadata is represented via Schema.org.

Cheers,

Andrea

----
[1]https://lists.w3.org/Archives/Public/public-sdw-wg/2016Jul/0164.html



On 26/07/2016 14:47, Linda van den Brink wrote:
> Hi all,
>
>
>
> Finally, some progress. I’ve begun restructuring the Best Practices
> document based on the structure of the DWBP (same grouping and
> ordering of BPs). I shuffled all the BPs around to the best of my
> ability based on discussions we had in various places. I may have
> missed some insights because I find it difficult to keep track of all
> the mailing list discussions sometimes, so comments are more than
> welcome.  I’ve not started merging/consolidating BPs yet, but will do
> if appropriate. I’m working on them one by one, now.
>
>
>
> http://w3c.github.io/sdw/bp/

>
>
>
> In particular, I welcome more detailed comments on the section in the
> BP on spatial metadata. http://w3c.github.io/sdw/bp/#bp-metadata

>
>
>
> I’ve got three BPs in that section at the moment.
>
>
>
> The first one is about spatial coverage and other spatial descriptive
> metadata. Getting there, but needs examples at least.
>
>
>
> The second is about CRS – there have been comments on this in the past
> as well as recent discussion, which I’ve tried to capture without
> making the section overly long or complex. Please review!
>
>
>
> The third is on making the entities within a spatial dataset indexable
> (it was SDWBP25 in the FPWD). Even though this is not really a spatial
> but a general issue I’ve retained it for now, because it’s useful
> information and not detailed in DWBP. And even though it’s not clearly
> about metadata (at least not on dataset level), this section seems the
> best fit for it. Also, this BP needs examples and can probably be improved.
>
>
>
> Your thoughts are appreciated!
>
>
>
> Linda
>
>
>

--
Andrea Perego, Ph.D.
Scientific / Technical Project Officer
European Commission DG JRC
Directorate B - Growth and Innovation
Unit B6 - Digital Economy
Via E. Fermi, 2749 - TP 262
21027 Ispra VA, Italy

https://ec.europa.eu/jrc/



This message contains information, which may be in confidence and may be subject to legal privilege. If you are not the intended recipient, you must not peruse, use, disseminate, distribute or copy this message. If you have received this message in error, please notify us immediately (Phone 0800 665 463 or info@linz.govt.nz<mailto:info@linz.govt.nz>) and destroy the original message. LINZ accepts no responsibility for changes to this email, or for any attachments, after its transmission from LINZ. Thank You.
Received on Wednesday, 27 July 2016 01:02:44 UTC

This archive was generated by hypermail 2.4.0 : Thursday, 24 March 2022 20:31:23 UTC