[Esip-documentation] Report on OGC meeting (1/2)

Wed Mar 26 11:24:52 EDT 2014

Hi Martin,

Has anyone volunteered to take the lead on NetCDF to ISO formalization
within the context of OGC?

Please note that we have moved off the geo-ide wiki and on to an esip wiki
for ongoing discussing and changes for ACDD.

http://wiki.esipfed.org/index.php/Category:Attribute_Conventions_Dataset_Discovery

(See outdated reference -
http://sis.apache.org/apidocs/org/apache/sis/storage/netcdf/package-summary.html
).

Thanks for the update,
Dave

David Neufeld
Information Services Division
CIRES Team Lead
NGDC / NOAA
david.neufeld at noaa.gov

On Tue, Mar 25, 2014 at 4:21 PM, Martin Desruisseaux <
martin.desruisseaux at geomatys.com> wrote:

> Hello all
>
> An OGC meeting is going on right now in Arlington. The meeting is not
> yet over, but there is a summary of some points discussed so far:
>
> Web Coverage Services (WCS)
> -------------------------------------------------
> A specification mapping GeoTIFF tags to standards elements (ISO) has
> been adopted recently. Such GeoTIFF-ISO mapping is similar to the
> NetCDF-ISO mapping defined by NOAA. Apache SIS already implements the
> NetCDF-ISO mapping [1], we should also implement the GeoTIFF-ISO mapping
> using that document. Note that this specification is not about the
> GeoTIFF format itself, however there is some talk about whether OGC
> should also write a specification for it. In the current state, the
> community maintaining the GeoTIFF specification is somewhat informal.
>
> Other data specification under work are NetCDF and JPEG2000. The
> NetCDF-ISO mapping currently implemented by SIS is based on NOAA
> documentation. If OGC defines formally the mapping in a specification,
> we should probably update SIS accordingly.
>
> Above paragraphs are about "data". On the "services" side, recently
> adopted specifications extending the core are:
>
> - CRS
> - range subsetting
> - scaling
> - interpolation (often used together with scaling, but not necessarily)
>
> The meteorological-oceanographic working group said that the CRS and
> range subsetting extensions worked well for them. However an Earth
> Observation and meteorological-oceanographic profiles of WCS may still
> be needed for other reasons, to be discussed in the "MetOcean" section
> below in this email.
>
> A public wiki is at [2].
>
>
>
> Transactional Web Coverage Services (WCS-T)
> -------------------------------------------------
> WCS-T 2.0 is a rewrite of WCS-T 1.4 without upward compatibility - the
> changes are major. WCS-T purpose is to insert, update and delete WCS
> coverage offerings. Specification for insert and delete operations are
> done, update operation is in progress. The difficulty for the update
> operation is to specify the criterion for determining if an update is
> allowed or not (e.g. replacing a 3-banded image by a 1-banded image
> should probably not be allowed).
>
>
>
> Web Processing Service (WPS)
> -------------------------------------------------
> A WPS 2 specification is under way. WPS 2 improvements compared to WPS 1
> are:
>
>   * Better support for process discovery
>   * Improved execution management (long running processes, ability to
>     delete a running job)
>   * Better support for synchronous / asynchronous execution
>
> A specification draft for public comment is expected by the end of April.
>
>
>
> Meteorological-oceanographic group (MetOcean)
> -------------------------------------------------
> MetOcean discussed about the extensions they wish to bring to WCS.
> Rational for extensions are related to data shapes: GRIDS, time series,
> cross sections, point collections (e.g. observations), vertical profiles
> (e.g. ascents), trajectories. The group emphases on the needs for
> sub-settings on the 4 axes, probably 5 axes in the future where the
> fifth axis would be "ensemble" (e.g. probability, discussed below).
> Keeping in mind that MetOcean uses two time axis (forecast time, model
> run reference time), we have a potential for 6 dimensional coverages.
> The group emphases also on slice, trim and sub-setting operations (e.g.
> trim X, trim Y, slice Z = horizontal view).
>
> Some extensions needed:
>
>   * Slice and trim requested in other CRS than the source data CRS.
>   * Want to advertise validity times for coverage data availability.
>   * Challenge: create 3D/4D grid from irregular grids with missing data.
>   * Needs to group coverages by collections (other amount of coverages
>     is unmanageable) with their own metadata. Note that the need to
>     define collection of coverages is probably a wider than the MetOcean
>     domain. Generalization will be investigated.
>   * Custom WCS operations: DescribeCoverageCollection, GetCorridorCoverage.
>
> An OGC document is hoped for the end of this year.
>
> The group provided some patterns of data extraction. For example
> extracting vertical profile data for a trajectory (marine example:
> sonar) = trim operation expressed in the CRS of the trajectory. The
> group had a discussion about vertical CRS of the kind "pressure in hPa
> relative to a changing datum (a pressure surface)". The action for now
> is to take a closer look to ISO 19111-2 (parametric CRS). I think that
> Apache SIS too should take a closer look to ISO 19111-2.
>
> The MetOcean group presented "ensemble forecasts": producing more than
> 20 parallel forecasts based on original observations in order detect
> "butterfly effect". Some statistical numbers of interest are quartile
> values, decile values, 95% and 5% percentile values, mean and mode. Open
> question is: can those needs be adressed by the NetCDF-Uncertainty
> extension?
>
> The MetOcean group has a projects on GitHub [3] providing the following
> resources:
>
>   * World weather symbols, as SVG or PNG files.
>   * WMO Regional Associations GeoJSON.
>   * WMO core metadata profile 1.3. They provide an application
>     performing validation for a profile of ISO 19115 metadata.
>
> The last point is related to Apache SIS, since we implement ISO 19115. I
> will create a "Provides a meterological profile of ISO 19115" JIRA task.
> Since I think there is an other Apache project related to climate, maybe
> there is an opportunity to contact each other here?
>
>
>
> Big data
> -------------------------------------------------
> Big data has been defined as the analysis on multi-dimensional arrays of
> size several orders of magnitude above engine's main memory. A
> discussion working group has been formed for investigating possible
> issues with OGC specifications for achieving this goal. Chairs have been
> nominated. As a side note, the European Space Agency (ESA) organizes a
> conference on big data from space on November 12-14th, 2014 in Fracati,
> Italy.
>
>
>
> Moving features
> -------------------------------------------------
> A reference implementation named "Mobmap" has been shown. This
> implementation run on Chrome browser and uses CSV files (points only) as
> inputs. They were discussion about using NetCDF as a more efficient
> binary storage format, but there is a difficulty in complying to the
> NetCDF "trajectory" convention. An alternative could be to take some
> liberties regarding the NetCDF trajectory convention, but this is
> something that peoples would prefer to avoid.
>
> The specification had only minor editions, and now includes the use case
> provided by Nadeem Anjum on this mailing list. A final version of Moving
> Feature specification is expected for December.
>
> They were an interesting discussion about JSon being - as surprisingly
> as it may seem - more verbose than XML for data like the Moving Feature
> ones, because of massive repetition of keywords. I'm not a JSon expert
> so I can not elaborate...
>
>
>
> CITE Tests (Team engine):
> -------------------------------------------------
> The "Team engine" is the testing framework at OGC. It is different than
> the "GeoAPI-conformance" module that we use for Apache SIS. OGC is
> working on making Team Engine easier to use - currently it has been
> reported that an expert needs 2.5 hours to configure and run tests. It
> is too early for Apache SIS to use Team Engine, since we do not yet
> implement web services. When we will start looking at CITE, ideally I
> would like to see if some CITE-GeoAPI integration are possible.
>
>
>
> Miscellaneous
> -------------------------------------------------
> Some related initiatives mentioned in the meeting are:
>
>   * Integrated Ocean Observing System (IOOS) [4]
>   * Integrated Justice Information System (IJIS)
>   * WMO Climate Data Management System Specification (CDMS)
>
> They were also a mention about recent and coming discussion in other
> organizations about whether we should keep leap second. The
> International Atomic Time (TAI) currently differs from Coordinated
> Universal Time (UTC) by 35 seconds due to leap seconds added in the last
> decades. Some organizations want to suppress leap seconds. No decision
> has been taken yet. Of course the decision does not depend on OGC, but
> opinions are collected.
>
> OGC is still experimenting ways to publish their specification as web
> pages. A prototype is available for the GeoPackage specification.
> However there is not yet a policy for allowing external projects - like
> Apache SIS - to provide links to a stable anchor of OGC specifications.
> For example if Apache SIS wants to link to a specific clause of an OGC
> specification, whether this will be possible is still an open question.
>
>     Martin
>
>
> [1]
>
> http://sis.apache.org/apidocs/org/apache/sis/storage/netcdf/AttributeNames.html
> [2] http://external.opengeospatial.org/twiki_public/CoveragesDWG/
> [3] https://github.com/OGCMetOceanDWG
> [4] http://www.ioos.noaa.gov/
>
>
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