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Re: BP restructuring: Metadata section

From: Andrea Perego <andrea.perego@jrc.ec.europa.eu>
Date: Sun, 31 Jul 2016 23:05:34 +0200
To: Linda van den Brink <l.vandenbrink@geonovum.nl>
Cc: "SDW WG (public-sdw-wg@w3.org)" <public-sdw-wg@w3.org>
Message-id: <f5b11302-5e1c-edf0-c2ce-c9cdfa4daeaf@jrc.ec.europa.eu>
Hi, Linda.

On 29/07/2016 10:35, Linda van den Brink wrote:
> Thanks for you useful feedback Andrea!

Happy you found it useful!

> I made some changes in the BP accordingly.
> - In BP1, I changed data type to spatial representation type. Also, in the listed types of spatial metadata I now reference BP2, about CRS, and BP4, about specifying spatial resolution (which is in the Data Quality section).
> - In BP2, I now mention the Geo-DCAT-AP approach for linking CRS
> - In BP3, I have made adjustments so that this BP is now not only about making entity level resources crawlable, but also metadata records about datasets. They can both follow the same general approach.

As far as BP3 is concerned, I wonder whether it may be worth adding the 
Geonovum testbed and GeoDCAT-AP as examples, the former for data and 
metadata, the latter for metadata.

About the possible relevance of GeoDCAT-AP here, this is related to the 
fact that one of the output serialisations is HTML+RDFa - see, e.g.:

http://bit.ly/1QqffsK

> - in BP4, I reference DQV
>
> Happy to receive code examples and more comments to improve these sections!

In BP1, BP2 & BP4 I've added some draft examples from GeoDCAT-AP about:
1. Spatial representation type (BP1)
2. CRS (BP2)
3. Data quality as conformance test result (BP4):

I've just submitted the relevant pull request:

https://github.com/w3c/sdw/pull/325

Do you think they are clear enough? Should they be further elaborated?

BTW, in BP4 I also added a placeholder for an example from DQV, since 
I'm unsure which examples we would like to include. DQV offers many, so 
I guess it would be useful to focus on those having an explicit "spatial 
flavour". And maybe we can elaborate them further.

> It would also be great if we could include a schema.org mapping for spatial metadata in the possible approach of BP3. As you noted, an open question is if a partial mapping is enough here.  My feeling is that a simplified mapping is enough. It depends on the requirements; which metadata attributes are the most useful for discovery?

Maybe an option would be to focus on what is in DCAT. We can create the 
mapping table merging the work concerning:
- the ISO 19115 to Schema.org mappings defined in the Geonovum testbed
- the ISO 19115 to DCAT mappings defined in GeoDCAT-AP

We can have a mapping table with 3 columns: (a subset of) ISO 19115, the 
corresponding DCAT terms, Schema.org.

If this makes sense to you, I can try to prepare a draft within the end 
of the week, and add it to the wiki.

Cheers,

Andrea


> -----Oorspronkelijk bericht-----
> Van: Andrea Perego [mailto:andrea.perego@jrc.ec.europa.eu]
> Verzonden: dinsdag 26 juli 2016 16:55
> Aan: Linda van den Brink; SDW WG (public-sdw-wg@w3.org)
> Onderwerp: 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/
>

-- 
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/
Received on Sunday, 31 July 2016 21:06:18 UTC

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