Proposal: direct link from Observation/Sampling to ultimate feature of interest

[dr-shorthair]

When revising SSN last year, a few requirements identified in om-lite never made it onto the agenda. One of these was the need to have links to both a sample and to the 'ultimate' feature of interest of an observation.

There is currently just one property - sosa:hasFeatureOfInterest - whose definition matches that from OGC O&M: it links to the proximate feature whose property is being observed. However, in the case where a sample is involved, this requires traversal of a property-chain to find what the ultimate feature-of-interest is ( sosa:hasFeatureOfInterest , sosa:isSampleOf ) . This adds complexity to some common data-discovery scenarios.

om-lite proposed to resolve this by have a separate property for the sample - oml:samplingStrategy. On reflection, this was unnecessarily obscure, and also undermined the integrity of the featureOfInterest property which O&M defined as the proximate foi (not the ultimate foi). So now I propose to meet the requirement with an explicit property hasUltimateFeatureOfInterest which corresponds to the property-chain mentioned above. I have implemented this in the branch https://github.com/w3c/sdw/tree/simon-observation-ultimateFOI - currently only the RDF, but will also make a proposal for modified text, else as an add-on if that is a better strategy.

[KathiSchleidt]

Many thanks! Now all properties are clearly named, no more sampled/sampling confusion, and nicely backwards compatible :) Just for clarification, does this then mean that the following mapping from O&M V2 is valid:

• O&M:featureOfInterest->sampledFeature ~ SOSA:hasUltimateFeatureOfInterest
• O&M sampledFeature ~ SOSA:isSampleOf
• O&M:sampledFeature ~ SOSA:isResultOf->hasFeatureOfInterest

Still open is the issue of Station modelling; to my view the Station should be the Platform hosting the Sensors but in many cases the Station is provided as FoI - any further clarification of this in light of UltimateFoI?

[dr-shorthair]

[rgcmme]

Maybe a bit off-topic for this issue but, in these patterns, the only term that is not included in SOSA is hasProperty. I still think that hasProperty and isPropertyOf should be moved to SOSA so people can use them in scenarios such as these without having to import the whole SSN.

[dr-shorthair]

Moved thread concerning hasProperty over to #5 so the original issue is not diluted.

[dr-shorthair]

Elaborated the story a bit for longer chains of samples:

and also thought about how it might also apply to sampling:

[nicholascar]

I think this is very useful! People want to cut to the case.

Can you add in a PROV-O alignment? I was hoping to find in PROV-O something like "follow a derivation chain right back to the oldest ancestor" but can't find on in the spec. prov:hadPrimarySource is not correct. Is there any other PROV-O property/axiom that would be the equivalent to the path prov:wasDerivedFrom+ as you have for sosa:isSampleOf+?

[smrgeoinfo]

Implications: every 'isSampleOf' relation has (at least notionally) a corresponding 'Sampling' event that specifies the proximate FeatureOfInterest and Procedure; the 'ultimate feature of interest' is a property of the Sampling event, recognizing the fundamentally human/interpretive aspect -- the 'why' someone is going to the trouble of defining the sample as an entity.

[smrgeoinfo]

Having an explicit 'ultimate feature of interest' is important because in some sampling derivation chains, the ultimate FOI for a child might be different from the ultimate FOI for a parent. Here is a diagram of an example:

[dr-shorthair]

I've started developing a formal proposal here:
https://github.com/w3c/sdw/tree/simon-ssn-extensions/ssn-extensions

[tidoust]

Those willing to review the SSN Extensions proposal online may use the following link:
https://rawgit.com/w3c/sdw/simon-ssn-extensions/ssn-extensions/index.html

@dr-shorthair, note the GitHub repository now has a “proposals” folder for documents that are to be reviewed and discussed in the IG before they take a more formal status. It might be worth moving the “ssn-extensions” folder there.

[dr-shorthair]

See w3c/sdw#1012

[tidoust]

Pull request merged. First version of the proposal now directly available from:
http://w3c.github.io/sdw/proposals/ssn-extensions/

Not sure how you'd like to proceed from now @dr-shorthair. You may continue to use this issue to refine the proposal. Or you may close this issue and track further feedback on the proposal in dedicated issues. Up to you :)

[dr-shorthair]

Follow up in #7