Re: Data Quality Vocab for SDW

Dear all,

Just a brief note about this, to
1: thank you for the input!
2: warn you that we've noted an action [1] on creating an example with DQV that shows how we could represent your case.
This may go as far as creating a specific instance of dqv:Dimension for granularity/precision.

Cheers,

Antoine

[1] https://www.w3.org/2013/dwbp/track/actions/264

On 3/9/16 2:37 PM, Heaven, Rachel E. wrote:
> Noting also that in the latest version of ISO 19115 (ISO 19115-1:2014) the spatial resolution of a dataset can also be expressed as a vertical distance, an angular distance (gco:Angle), or as levelOfDetail (gco:CharacterString), in addition to the previous options of distance (=horizontal ground distance) or equivalent scale.
>
> Cheers,
> Rachel
>
> -----Original Message-----
> From: Andrea Perego [mailto:andrea.perego@jrc.ec.europa.eu]
> Sent: 09 March 2016 10:23
> To: Antoine Isaac
> Cc: Phil Archer; Linda van den Brink; Riccardo Albertoni; 'public-sdw-comments@w3.org'
> Subject: Re: Data Quality Vocab for SDW
>
> Hi, Antoine.
>
> I can contribute a use case concerning geospatial metadata.
>
> One of the information that is typically included concerns the spatial resolution of a dataset. This is expressed either by a distance - e.g., data have a 1km resolution - or with an equivalent scale (i.e., a
> fraction) - e.g., 1:1,000,000.
>
> I include below two XML code snippets to show how this is expressed in ISO 19115:
>
>
> Spatial resolution as distance (1,000 m):
>
> <gmd:spatialResolution>
>     <gmd:MD_Resolution>
>       <gmd:distance>
>         <gco:Distance
> uom="http://standards.iso.org/ittf/PubliclyAvailableStandards/ISO_19139_Schemas/resources/uom/ML_gmxUom.xml#m">1000</gco:Distance>
>       </gmd:distance>
>     </gmd:MD_Resolution>
> </gmd:spatialResolution>
>
>
>
> Spatial resolution as equivalent scale (1:1,000,000):
>
> <gmd:spatialResolution>
>     <gmd:MD_Resolution>
>       <gmd:equivalentScale>
>         <gmd:MD_RepresentativeFraction>
>           <gmd:denominator>
>             <gco:Integer>1000000</gco:Integer>
>           </gmd:denominator>
>         </gmd:MD_RepresentativeFraction>
>       </gmd:equivalentScale>
>     </gmd:MD_Resolution>
> </gmd:spatialResolution>
>
>
> Property dct:conformsTo (or a specific subproperty to be defined) can be
> used to specify the spatial resolution of a dataset / distribution, but
> three things are missing:
>
> 1. How to model the notion itself of (spatial) resolution.
>
> 2. How to express in RDF quantity values (e.g., 1m, 2km, 3s, 4h, 5l) and
> fractions.
>
> 3. How to glue #1 and #2
>
> Actually, solutions exist to address point #2 - as the QUDT vocabulary
> [1] mentioned during our first joint call [2]. But, to the best of my
> knowledge, there's currently no best practice on how to use them.
>
> This situation is also the reason why in GeoDCAT-AP the decision taken
> was to dump spatial resolution into a free-text field - a provisional
> "mapping" meant to be replaced in the future with a more appropriate
> approach.
>
>
> So, looking at DQV, I wonder whether dqv:QualityMeasure (and the related
> properties and classes) are generic enough to model also this
> information. E.g. (just trying):
>
>
> a:Dataset dqv:hasQualityMeasure [ a dqv:QualityMeasure ;
>     dqv:hasMetric :spatialResolutionAsEquivalentScale ;
>     dqv:value "0.000001"^^xsd:decimal ] .
>
>
> another:Dataset dqv:hasQualityMeasure [ a dqv:QualityMeasure ;
>     dqv:hasMetric :spatialResolutionAsDistanceInMetres ;
>     dqv:value "1000"^^xsd:decimal ] .
>
>
> Not sure this is correct. In particular, it is unclear to me whether
> this is the correct way (in DQV) of modelling the notions of resolution,
> distance / equivalent scale, and units of measurement. In the examples
> above, they are all merged together in one instance of dqv:Metric -
> which, besides resulting in a strange N-headed beast (formally
> speaking), is not scalable.
>
>
> A final (general) note:
>
> In my understanding, spatial (as well as temporal) resolution can be
> considered as a specific type of data granularity. From this
> perspective, and in order to ensure consistency and interoperability, it
> would be desirable to have a DQV-based approach to model the general
> notion of granularity, that could then be used as a basis for specific
> types (as spatial / temporal resolution).
>
>
> Cheers,
>
> Andrea
>
> ----
> [1]http://www.qudt.org/
> [2]https://www.w3.org/2016/02/17-sdw-minutes
>
>
> On 07/03/2016 08:08, Antoine Isaac wrote:
>> Dear Phil, Linda,
>>
>> Thanks a lot for this. This is in fact quite an important requirement;
>> I've flagged it as an issue at
>> https://www.w3.org/2013/dwbp/track/issues/243
>>
>> It may however take some time to come back to you, as we still have many
>> issues. Actually we had granularity in scope, when we started with DQV.
>> But this was downplayed as the DWBP requirements were very vague then.
>> Do you have some precise examples from SDW, i.e. showing what data would
>> look like, and its problems?
>>
>> Best,
>>
>> Antoine
>>
>> On 3/3/16 10:46 AM, Phil Archer wrote:
>>> Antoine, Riccardo,
>>>
>>> As Antoine will recall, the Spatial Data WG, here represented by
>>> Linda, has a particular interest in the DQV. An issue that comes up a
>>> lot in spatial datasets is that of precision and accuracy (the fact
>>> that Magna Carta was signed in 1215 is accurate, just not very
>>> precise, saying it was signed at 1215-06-15T00:00:00 is precise but
>>> inaccurate). It occurs in general datasets too but it's particularly
>>> acute for spatial.
>>>
>>> On last night's SDW call, I was asked to put you in touch with linda
>>> specifically to talk about this, in particular, how you might express
>>> these ideas in the DQV?
>>>
>>>
>>> Process note: I'm archiving this in the SDW's public comment list to
>>> avoid having to sign you all up to yet another mailing list.
>>>
>>> For tracker this is ACTION-149
>>>
>>
>
> --
> Andrea Perego, Ph.D.
> Scientific / Technical Project Officer
> European Commission DG JRC
> Institute for Environment & Sustainability
> Unit H06 - Digital Earth & Reference Data
> Via E. Fermi, 2749 - TP 262
> 21027 Ispra VA, Italy
>
> https://ec.europa.eu/jrc/
>
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Received on Tuesday, 15 March 2016 15:42:51 UTC