- From: Andrea Perego <andrea.perego@jrc.ec.europa.eu>
- Date: Tue, 12 Apr 2016 19:42:51 +0200
- To: Riccardo Albertoni <albertoni@ge.imati.cnr.it>
- Cc: Antoine Isaac <aisaac@few.vu.nl>, "Heaven, Rachel E." <reh@bgs.ac.uk>, Phil Archer <phila@w3.org>, Linda van den Brink <l.vandenbrink@geonovum.nl>, "public-sdw-comments@w3.org" <public-sdw-comments@w3.org>
Dear Riccardo,
Many thanks for having integrated the examples in the DQV specification!
About this point:
>> 2. As Rachel said earlier in this thread [1], the new ISO 19115
>> supports the possibility of specifying resolution as vertical or
>> angular distance, and with level of detail.
>>
>> Based on the DQV example, I guess the first two should be modelled
>> as instances of dqv:Metric (:spatialResolutionAsVerticalDistance &
>> spatialResolutionAsAngularDistance), whereas the level of detail
>> should be specified with a dqv:QualityAnnotation (or a subclass -
>> :LevelOfDetail).
>>
>> Is this correct?
>
> Sorry, I am not sure to fully understand your question, why do you
> think that the level of detail should be expressed as a Annotation?
My fault, sorry. I missed to explain the context.
I was referring specifically to how this is done in ISO 19115-1:2014,
where (as Rachel said [1]) the "level of detail" is specified by using
element gco:CharacterString - which is meant to be used with free text /
alphanumeric strings (including URLs), and not with numbers (as expected
by dqv:value, right?).
Cheers,
Andrea
----
[1]https://lists.w3.org/Archives/Public/public-sdw-comments/2016Mar/0008.html
On 12/04/2016 18:29, Riccardo Albertoni wrote:
> Hi Andrea,
>
> Thanks for your feedback, my replies are inline.
>
> On 10 April 2016 at 00:39, Andrea Perego <andrea.perego@jrc.ec.europa.eu
> <mailto:andrea.perego@jrc.ec.europa.eu>> wrote:
>
> Hi, Antoine.
>
> I went through the 7 Apr 2016 version of DQV, and I saw that in
> Section 5.13 ("Express dataset precision and accuracy") the examples
> include one on spatial resolution :)
>
> http://w3c.github.io/dwbp/vocab-dqg.html#ExpressDatasetAccuracyPrecision
>
> I have a couple of questions - mainly to better understand how
> spatial resolution can be modelled in DQV:
>
>
> 1. The first is specifically related to the "spatial resolution as
> distance in metres" example. The example specifies explicitly the
> unit of measure used:
>
>
> :myDatasetPrecision a dqv:QualityMeasurement ;
> dqv:hasMetric :spatialResolutionAsDistanceInMetres ;
> dqv:value "1000"^^xsd:decimal ;
> sdmx-attribute:unitMeasure
> <http://www.wurvoc.org/vocabularies/om-1.8/metre>
>
> :spatialResolutionAsDistanceInMetres a dqv:Metric;
> skos:definition "It expresses dataset resolution as distance in
> Metres"@en ;
> dqv:expectedDataType xsd:decimal ;
> dqv:inDimension dqv:precision
>
>
> So, I wonder whether it'd rather be re-written as:
>
>
> dqv:QualityMeasurement ;
> dqv:hasMetric :spatialResolutionAsDistance ;
> dqv:value "1000"^^xsd:decimal ;
> sdmx-attribute:unitMeasure
> <http://www.wurvoc.org/vocabularies/om-1.8/metre> .
>
> :spatialResolutionAsDistance a dqv:Metric;
> skos:definition "It expresses dataset spatial resolution as
> distance"@en ;
> dqv:expectedDataType xsd:decimal ;
> dqv:inDimension dqv:precision .
>
>
> In other words, the relevant instance of dqv:Metric needn't be bound
> to a specific unit of measure - or I'm wrong?
>
> You are right, I've changed it accordingly.
>
>
> Also, I wonder how, by using this approach, it should be possible to
> specify spatial resolution as "equivalent scale" (e.g., 1:1,000,
> 1:1,000,000, etc.) - i.e., with a fraction, without unit of measure.
> It would be great to have an example also on this!
>
> I'm making a try below:
>
>
> dqv:QualityMeasurement ;
> dqv:hasMetric :spatialResolutionAsEquivalentScale ;
> dqv:value "0.000001"^^xsd:decimal .
>
> :spatialResolutionAsEquivalentScale a dqv:Metric;
> skos:definition "It expresses dataset spatial resolution as
> equivalent scale, by using a representative fraction (e.g., 1:1,000,
> 1:1,000,000)."@en ;
> dqv:expectedDataType xsd:decimal ;
> dqv:inDimension dqv:precision .
>
>
> Does this make sense?
>
>
> It makes sense to me, I have added it in the example.
>
>
>
>
> 2. As Rachel said earlier in this thread [1], the new ISO 19115
> supports the possibility of specifying resolution as vertical or
> angular distance, and with level of detail.
>
> Based on the DQV example, I guess the first two should be modelled
> as instances of dqv:Metric (:spatialResolutionAsVerticalDistance &
> spatialResolutionAsAngularDistance), whereas the level of detail
> should be specified with a dqv:QualityAnnotation (or a subclass -
> :LevelOfDetail).
>
> Is this correct?
>
> Sorry, I am not sure to fully understand your question, why do you
> think that the level of detail should be expressed as a Annotation?
>
>
>
>
> Finally, on a different note:
>
> I think there's a typo in the following example (always Section 5.13):
>
> :spatialAccuracy a dqv:Metric;
> skos:definition "It returns the percentage of spatial element
> that are found accurate acconding to methodology XYZ"@en ;
> dqv:expectedDataType xsd:decimal ;
> dqv:inDimension ldqd:semanticAccuracy
>
>
> s/acconding/according/
>
>
> I have corrected it.
> Many thanks.
> Riccardo
>
> Thanks!
>
> Andrea
>
> ----
> [1]https://lists.w3.org/Archives/Public/public-sdw-comments/2016Mar/0008.html
>
>
>
> On 15/03/2016 16:42, Antoine Isaac wrote:
>
> 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
> <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 <mailto: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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>
> --
> 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/
>
>
>
>
> --
> ----------------------------------------------------------------------------
> Riccardo Albertoni
> Istituto per la Matematica Applicata e Tecnologie Informatiche "Enrico
> Magenes"
> Consiglio Nazionale delle Ricerche
> via de Marini 6 - 16149 GENOVA - ITALIA
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> <mailto:Riccardo.Albertoni@ge.imati.cnr.it>
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Received on Tuesday, 12 April 2016 17:43:34 UTC