See also: IRC log
<billroberts> ah hi Phil - we're stuck with the webex
<billroberts> being asked for MIT certificate
<billroberts> will try, 2 secs
<billroberts> yes, success - many thanks Phil
i cando it if you likje!
<scribe> scribe: kerry
<scribe> scribeNick: kerry
propose: approve minutes https://www.w3.org/2016/03/23-sdwcov-minutes
<billroberts> +1
+1
<dmitrybrizhinev> +1
resolved approve minutes https://www.w3.org/2016/03/23-sdwcov-minutes
RESOLUTION: approve minutes https://www.w3.org/2016/03/23-sdwcov-minutes
bill: reviewed requirements,
talked about subsets and web-friendly formats, reviewed data on
the Web view
... with some members of that group on the call
... large portions of coverage data are gridded (but not
all)
... ro gridded datasets sections can be defined farly
easily
... will work on grid first, and also look inot non-gridded for
important cases
<billroberts> https://www.w3.org/2015/spatial/track/actions/152
bill: kerry does not like
'subsetting" but I don't mind either way
... "extract" or something comes up all the time
... mimimise misunderstandings
<billroberts> kerry: there was a raging debate on mailing list. Most people don't mind
<billroberts> suggestions: extract, filter, ...
<kerry summarises email discussion>
bill: thinks extract may be less confusing
Proposed: that we use "extract" as the main word in most places (and mention subsetting as used for same thing when introducing)
<billroberts> +1
+1
<Maik> +1
<dmitrybrizhinev> +1
<ScottSimmons> +1
<Duo> 0
<sam> +1
RESOLUTION: to encourage the use of "extract" as the main word in most places (and mention subsetting as used for same thing when introducing)
<billroberts> https://github.com/ANU-Linked-Earth-Data/ontology
<sam> More verbose link with examples: https://github.com/ANU-Linked-Earth-Data/main-repo/wiki/NotesForCoveragesSubgroupApril06
<dmitrybrizhinev> no I can't hear
<sam> sorry, not sure what's going on with phone
<Duo> should I introduce things while he gets that sorted?
<sam> yes please
<dmitrybrizhinev> yes
Duo: 2 key points: using dggs for data (landsat data)
<billroberts> DGGS: Discrete Global Grid System
Duo: stores geospatail data in a
standardised format
... lokking to put it into an rdf datacube using fuseki triple
store and elda api
... dimitry is developing ontology inspired by coveragejson
Dmitry: I have been writing the
coveragejson spec in owl
... see the posted example and you can see it in rdf
... lets you define axes and link them to a crs, and link
values to some other meanig
... this is the way coveragejson does it
<sam> is this working?
<dmitrybrizhinev> nope, just echoes
<problems with sound>
<sam> sure, that works. I only have a little bit to say.
<sam> my part of the project is to build the API which will be used by the client app to access our satellite data
<sam> I think Duo explained some of that before (Fuseki + Elda)
maik: interesting to see
coveragejson moving this way
... what is the main motivation/
<sam> We've been trying to encode our data as RDF, but expose the service as a simple REST-ish API (at Kerry's suggestion)
dmitrybrizhinev: seemed to be a good way to organise the data -- somethin like rdf data cube but is more efficient that rdf datacube
maik: we come from the netcdf direction and just want a little bit of linking..
<sam> At the moment, I'm mostly interested in the group's feedback on (1) the suitability of SPARQL vs. REST-ish API from web developers' perspective and (2) best format for delivering data (JSON-LD, RDF/JSON, etc.)
maik: how do you want to use it
<sam> (/end comments)
dmitrybrizhinev: exactly how it
would be used is not really clear
... assuming that something a bit like the datacube would be
useful...
billroberts: linked data and rdf
in general offers the ability to link to anything, becuase
everything gets an identifier
... every observation, datapoint, has a URI, so you can stuff
about it
... other reason is you can combine data eg by sparql queries
over one or several triple stores
... one sapect is http, another is standardisation
... depends on who wants to use the data and the tools they are
used to
... works very well for metadata and alos provenance of data
processing
... my first thought on seeing the rdf here is that he numbers
may need a concise microformat....
dmitrybrizhinev: that is what coveragejson does -- or could it even be a binary file
billroberts: my fistreaction is that then there is not a lot of point in using rdf may be the worst of both worlds
dmitrybrizhinev: do you have a
suggestion? this has been discussed many times -- its too much,
the space expolodes
... what if it was an rdf list, and json-ld can encode into a
json array
... would this be the best of both worlds?
billroberts: even people that
like rdf hate rdf lists...
... maybe an approach like this linking to data in another rep
would do...
... and link to a separate url to retun json in a file or
something
... could be more like coveragejson -- could addmetadata in rdf
while using json for the numbers
dmitrybrizhinev: yes, canot see rdf for terrabyte datasets
Duo: melodies
<Maik> important: people don't fetch terrabytes anyway, always just small parts, it's all about the API
billroberts: yes coverage json is a product of the melodies project
duo; looking at <tiles?..> and client applicatins
<billroberts> kerry: is coverageJSON metadata sufficient to describe a specific data point? or is it just metadata for a whole dataset or large part of a coverage?
<dmitrybrizhinev> Yes, this was a suggestion before - that there can be a clear distinction between the way the data is stored and the way it is represented in response to a query
<billroberts> kerry: if coveragejson provides a way to uniquely identify any element in the data, that should be sufficient
<billroberts> kerry: could make a URL pattern that allows identifying an extract using that
<billroberts> kerry: do we then have a sufficiently fine-grained way of identifying 'chunks'
Maik: if you want to identify a
single datapoint that would be a combination of a parameter
plus a domain index (e.g. time)
... this could be put into a url
<Maik> #x=1,y=2,t=2
Maik: index based subsetting, but
sometimes perople want coordinates instead...
... some apis alsways use coordinates and not indices
... how do we assess what is good an what is not
... its hould not include any type of query language so even if
you change underlying technologythe reference does not
change
billroberts: the API or method of
identifying extract should be independetn of
implementation
... but this is spatial data on the web, so needs to be http
and uris
... needs to to be "simple" whatever that is -- needs to be
easy for some community of data users
... we are agreeing some kind of exchange language between
people who have a lot ov coverage data and some people on the
web who need it
Maik: e/g like leaflet, always
lat/long, no other projections -- so even if dataset is not
stored that way it should be usabl that way
... you should offer an API based on lat/longs, so you don't
need to know how to do british national grids
billroberts: yes, probably
wgs84
... that data manger should take charge of conversion between
grid space and user CRS
... we want something that will persist for a while... needs to
be not too closely tied to specific things
... we want something that is not too verbose becuase data is
large and we need to transfer it in a finite amount of time
<Maik> http://reading-escience-centre.github.io/covjson-playground/
billroberts: browers will run out of resources (time and space)
maik; havong lots of examples and tools avaialble e.g. plugins, libraries
billroberts: ANU work is looking
at data through an API plus something that is consuming
it
... would like document of waht works well and what does
not
... will develop a stra man set of criteria
... wouild like examples with real data,as well as simple
illustrations
... reminder that you are encouraged to edit pages on working
group wiki to share information and documents for
discussion
... eg strangth and wekanesses
due: yes we can do that in two weeks
<scribe> ACTION: Duo to write up what has been learn on the wiki for 2 weeks [recorded in http://www.w3.org/2016/04/06-sdwcov-minutes.html#action01]
<trackbot> Error finding 'Duo'. You can review and register nicknames at <http://www.w3.org/2015/spatial/track/users>.
<billroberts> trackbot, end meeting