Re: Georeferenced sensor and coverage data

Hello Peter, all,

So actually we have two definitions of the term 'georeference'? A general
definition (link a spatial thing to a geographical geometry (some
coordinates)), and a narrower definition from ISO 19123?

And if a coverage in the sense of ISO 19123 has a georeference built in,
why do we need a requirement saying that it should be possible to
georeference coverages?

As you can probably tell, I am still confused. If we keep the requirements
as they are, would it be possible to extend the descriptions so they will
be less confusing?

Greetings,
Frans



2015-06-01 16:46 GMT+02:00 Peter Baumann <p.baumann@jacobs-university.de>:

>  Hi Frans,
>
> not quite, coverages are built around georeferences. The difference is:
> - a coverage (at least the ones we are considering here) _has_ a
> georeference built in
> - a non-georeferenced object can reference some other object that has a
> georeference.
>
> So a coverage does not need to reference anything for having
> geocoordinates, they are part of the coverage object.
>
> Now let us look into what a "georeference" is. Can be a single point (eg,
> a point feature), can be an area (eg, a satellite image).
> If some other object links to a point in the sense "I sit where this guy
> sits" you can dereference this and get a point location for the linking
> object.
> If this object links to a coverage in this sense then it will sit where
> the image sits: in an area.
>
> Whether such a link is meaningful depends on what you want.
>
> -Peter
>
>
>
>
> On 06/01/15 16:33, Frans Knibbe wrote:
>
> Hello Alejandro, Kerry, Peter,
>
>  I think the intention of the two requirements is dawning on me now:
> There is a need for georeferencing coverage data and sensor data because
> the two models that the WG has indentified as the starting point for
> further work (ISO 19123 for coverage data, SSN for sensor data) do not
> support georeferencing at the moment.
>
>  I think it would help if we extend the requirement description a bit to
> make that clear.
>
>  Greetings,
> Frans
>
> 2015-05-31 13:03 GMT+02:00 <Kerry.Taylor@csiro.au>:
>
>>  Frans,
>>
>> I think they are different.  Linkability was all about “*different facts
>> in different data sets” *whereas the two “georeferenced...” requirements
>> are particularly asking that those 2 ontologies  include georeference
>> capability (ssn, for example, does not in its current form – instead it
>> asks you get it from some arbitrary other ontology. Users want more help
>> here – they want to be told where to get it from – this could be in ssn
>> itself, but more likely we will just decide to say in ssn  to use whatever
>> we recommend in bp . In this case it is perhaps true that the different
>> requirements would collapse to a single solution – nevertheless they are
>> different requirements ).
>>
>>
>>
>> Kerry
>>
>>
>>
>> *From:* Peter Baumann [mailto:p.baumann@jacobs-university.de]
>> *Sent:* Friday, 29 May 2015 3:47 AM
>> *To:* Frans Knibbe; Alejandro Llaves
>> *Cc:* SDW WG Public List
>> *Subject:* Re: Georeferenced sensor and coverage data
>>
>>
>>
>> Hi Frans,
>>
>> not sure, but I understand that "spatial data" has its georeference built
>> in (through particular technical means, eg, in the coverage model) whereas
>> the linkability text just demands that any data can be connected to such
>> georeferenced data:
>>
>> *"Spatial data on the Web should be linkable (by explicit relationships
>> between different facts in different data sets), to other spatial data and
>> to or from other types of data."*
>>
>>
>> best,
>> Peter
>>
>>
>> On 05/28/15 18:54, Frans Knibbe wrote:
>>
>>  Hello Alejandro,
>>
>>
>>
>> I wonder if there should be separate requirements for Georeferenced
>> coverage data
>> <http://w3c.github.io/sdw/UseCases/SDWUseCasesAndRequirements.html#GeoreferencedCoverageData>
>> and  Georeferenced sensor data
>> <http://w3c.github.io/sdw/UseCases/SDWUseCasesAndRequirements.html#GeoreferencedSensorData>.
>> Aren't those requirements covered by the Linkability requirement
>> <http://w3c.github.io/sdw/UseCases/SDWUseCasesAndRequirements.html#Linkability>?
>> If this requirement is met, anything can be georeferenced.
>>
>>
>>
>> Regards,
>>
>> Frans
>>
>>
>>
>> --
>>
>> Frans Knibbe
>>
>> Geodan
>>
>> President Kennedylaan 1
>>
>> 1079 MB Amsterdam (NL)
>>
>>
>>
>> T +31 (0)20 - 5711 347 <%2B31%20%280%2920%20-%205711%20347>
>>
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>>
>> www.geodan.nl
>>
>> disclaimer <http://www.geodan.nl/disclaimer>
>>
>>
>>
>>
>>
>>  --
>>
>> Dr. Peter Baumann
>>
>>  - Professor of Computer Science, Jacobs University Bremen
>>
>>    www.faculty.jacobs-university.de/pbaumann
>>
>>    mail: p.baumann@jacobs-university.de
>>
>>    tel: +49-421-200-3178, fax: +49-421-200-493178
>>
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>>
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>>
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>> "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)
>>
>>
>>
>>
>>
>>
>
>
>  --
>  Frans Knibbe
>  Geodan
> President Kennedylaan 1
> 1079 MB Amsterdam (NL)
>
>  T +31 (0)20 - 5711 347
> E frans.knibbe@geodan.nl
> www.geodan.nl
> disclaimer <http://www.geodan.nl/disclaimer>
>
>
> --
> Dr. Peter Baumann
>  - Professor of Computer Science, Jacobs University Bremen
>    www.faculty.jacobs-university.de/pbaumann
>    mail: 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, mail: 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)
>
>
>
>


-- 
Frans Knibbe
Geodan
President Kennedylaan 1
1079 MB Amsterdam (NL)

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