MIG workshop on WCS-based INSPIRE download services

Joint Research Centre (JRC)
Leonardo meeting room, Bdg. 26a
Ispra, Italy
14-15 October 2014

Agenda

Day 1: 14 October 2014

  1. Introduction to WCS and coverages (Peter Baumann, Jacobs University Bremen, Germany) [Slides: 20141014_WCS_Intro_Baumann.pdf]
    [9:30-10:30]
    [Seminar open to JRC staff ]
    ---------------
    Coffee break
    ---------------
  2. Welcome and approval of the agenda. MIF overview (Michael Lutz, JRC) [Slides: 20141014_MIF_Overview_Lutz.pdf]
    [11:00 – 11:15]
  3. Tour de table
    [11:15 – 11:30]
  4. Technical Guidance for INSPIRE download services - State of play - JRC study on WCS (Alexander Kotsev, JRC) [Slides: 20141014_WCS_Workshop_JRC_Kotsev.pdf]
    [11:30 – 12:00]
  5. Extension of INSPIRE download services TG for observation data (Simon Jirka, 52North, Germany) [Slides: 20141014_INSPIRE_SOS_Jirka.pdf]
    [12:00 - 12:30]
    ---------------
    Lunch break
    ---------------
  6. Presentations of participants on experiences/issues with WCS
    [14:00 – 15:30]
  7. OGC WCS Met/Ocean profile (Ian Edwards, Met Office, UK) [Slides: 20141014_WCS_2.0_MetOcean_Edwards.pdf]
    [16:00 – 16:45]
  8. Summary and wrap-up Day 1
    [16:45 - 17:30]

------------------------------------
Social Dinner in Angera [20:00]
------------------------------------

Day 2: 15 October 2014

  1. WCS as an INSPIRE download service (discussion)
    [09:00 – 10:00]
  2. Requirements and recommendations on coverages in the Data Specifications TGs
    [10:00 – 11:00]
  3. Relation of WCS and data representation (discussion)
    [11:30 – 12:30]
    ---------------
    Lunch break
    ---------------
  4. Other aspects related to coverages / WCS (discussion)
    [14:00 – 15:30]
    • View services for coverage data
    • quality of service
      ---------------
      Coffee break
      ---------------
  5. Workshop wrap-up. Next steps, actions. MIG engagement
    [16:00 – 16:30]

Minutes

Introduction to WCS and coverages

Peter gave an introductory presentation illustrating the underlying concepts for OGC standards on coverages and the web coverage service. He also introduced the WCS core and extension specifications as well as the existing WCS application profiles.

[The presentation was open to JRC staff and was attended by around 25 JRC staff members from the Water Resources Unit (H.01), Forest Resources and Climate Unit (H.03), Monitoring Agricultural Resources Unit (H.04), Land Resource Management Unit (H.05), Digital Earth & Reference Data Unit (H.06), Climate Risk Management Unit (H.07), Global Security and Crisis Management (G.02)]

Discussion:
  • WCS 2.0 is not backwards-compatible with WCS 1.0.
  • Several products implement WCS 2.0 core specification. It is unclear which of the extensions are commonly supported. The application profiles provide bundles of core & extension functionality.

Welcome and approval of the agenda

The agenda was approved as proposed. Michael gave a short introduction on the INSPIRE maintenance and implementation framework and work programme (MIWP). The work on download services for coverage data has been proposed as action MIWP-7 for the MIWP. The current workshop should serve the purpose to define the scope for this action more precisely and define a draft work plan / terms of reference for a specific MIG sub-group. It should also help to define the rationale and impact of carrying out the proposed work.

Tour de table

Participants shortly introduced themselves, their WCS and their interest in the workshop. See motivation statements in the participants section.

Technical Guidance for INSPIRE download services - State of play

Alexander presented the JRC study on mapping the requirements from the INSPIRE IRs for download services to the WCS specification and concepts. A number of discussion points were raised for discussion on day 2.

Discussion:
  • Peter: Don’t get INSPIRE-specific solution, but work together with OGC. Would be great to have a WCS-SOS link for the wider community.
  • Peter: Definition of coverage as spatial object makes sense.
  • James: The WCPS should also be discussed in this context. We should distinguish between an abstract specification what a download service should do. Michael: INSPIRE, this distinction is made between Implementing Rules (IRs) legal acts and Technical Guidelines (TGs).
  • Michael: We received the feedback from MS that implementers don’t want to have too many options, but step-by-step instructions. James/Michael: We should distinguish in the TGs between requirements for software/solution providers (who want to build INSPIRE-compliant products) and requirements for data/service providers (who want to use INSPIRE-compliant products)

Extension of INSPIRE download services TG for observation data

Simon presented the outcomes of the ARE3NA study on extending the INSPIRE TGs for download services to add implementation guidance for download services for observation data based on the OGC SOS specification.

Discussion:
  • James: Req. 22 [?] ETRS89 is not a CRS but only a datum - should be replaced by epsg:4258 (geographic coordinates based on ETRS89)
  • Ilkka: Why does the SOS have to provide download of whole data set? Michael: This is a requirement for download services stated in the INSPIRE Directive and NS IRs.
  • Peter: How do agencies/organisations decide which standard/TG option to choose?
  • Ian: Dataset is what is defined in the catalogue. James: This gets difficult if data and service providers are different. Thus, it is also an organisational issue.
  • Peter: There was a lot of discussion in WCS 2.0 on how much metadata to put into the WCS. It was decided to put in very little, but allow links to metadata records.

Presentations of participants on experiences/issues with WCS

James Passmore, Tim Duffy (British Geological Service, UK)

James showed examples on how to use WCPS to reclassify values in a coverage on the fly, e.g. to highlight areas whose superficial thickness is within a specified range. WCPS queries are expressed using simple "Map algebra"-like syntax specified in WCPS specification.

Next version of WCPS will merge data and metadata - based on outcomes of the EarthServer project.

Discussion:
  • INSPIRE compliance:
    • multi-linguality not supported by rasdaman
    • added extended capabilities
    • add most of the metadata in the DescribeCoverage operation
    • no on-the-fly coordinate conversion (default for offshore data: epsg:4326 or British national grid) - this is only supported by rasdaman enterprise
  • Peter: Capabilities document - either big and you need to find what you want or small and you're likely to not find what you are looking for --> dependencies on OWS Common

Jukka Rahkonen (Information centre of the Ministry of agriculture and forestry, Finland)

Jukka presented the Finnish implementation for providing orthophotos. he reported that many users use the GDAL WMS driver to download images through WMS. He suggested to have a WCS as a second option for file download (in addition to providing simple download of tiles), since using the WCS for orthophotos at native resolution may lead to increased costs for fast-access disks.

Discussion:
  • A hybrid solution could be used based on WCS query that returns an atom feed with links to download locations. This would be the opposite of the currently suggested hybrid solution for Atom feeds pointing to WFS queries for accessing the data sets.

Olav Peeters (Belgian Interregional Environment Agency)

Olav presented the high-resolution air quality model for Belgium, containing 650k points in a 10x10m grid, resulting in a 2.5GB geoTIFF. He stressed that INSPIRE needs to evolve and support advanced use cases (beyond simple file download).

Pascal Derycke and Laurent Dubroca (JRC, Water Resources Unit)

Pascal and Laurent presented the JRC's work on GMIS (Global Marine Information System) and EMIS (European Marine Information System), which provide marine information in netCDF in 9/4 km (GMIS) and 4/2 km (EMIS) resolution.

The implementation is based on MapServer 6.4.1 and includes additional parameters for the dataset (= observed property) and control time dimension.

To create statistical reports, Pascal and Laurent have developed r scripts that directly access the WCS, rather than downloading data first and then doing the analysis on the requester's computer.

Marie Lambois (IGN, France)

Marie reported that currently no WCS is used in IGN-France, but several coverage data sets (elevation, orthophotos) are being served through WMS and WMTS. There is a simple ordering interface for downloading data. WCS is considered to be for advanced users who need to access the real data values and geo-referenced data rather than just view the data on a map.

She proposed that the MIG activities should focus on a simple "Core" INSPIRE service, which is extensible according to data needs. Also, it should be clarified, which INSPIRE themes could be served through WCS.

Jorge Escriu Paradell (Institut Cartogràfic i Geològic de Catalunya)

Jordi explains the main characteristics of the WCS service currently provided by his organization to deliver elevation data (DTM) at 15 meters and 5 meters resolution.
Discussion:
A question was raised on why did ICGC use WCS 1.0.0 and 1.1.0. Jordi answered that ICGC implemented this WCS service 4 years ago and it is hardly used at the moment. We may consider moving to WCS 2.0.1 if this version of the standard is finally selected as an INSPIRE download service option. In that case, the change should not be a problem if supported by OS software.

OGC WCS Met/Ocean profile (Ian Edwards, Met Office, UK)

Ian presented the OGC WCS Met/Ocean profile, which includes best practices specifically for 4-dimensional climate data cubes. It recommends CF-netCDF (Climate forcasting conventions/best practices for netCDF), BUFR, or [???] as formats and defines the following additional concepts/operations:
  • MaskedCoverage - could become a more generic
  • CoverageCollection - new operation DescribeCoverageCollection
  • GetCoverageByPolygon - returns MultiPointCoverage --> should probably be done using FilterEncoding
  • GetCoverageByCorridor - e.g. meteo data along a buffer around a flight path
Discussion:
  • Is this profile useful for INSPIRE? Shouldn't we keep things simple? Ian: The extensions were added because WCS core was not sufficient for use cases. The profile needs more work on ocean-related requirements and additional use cases beyond air navigation.
  • Which WCS extensions are required? [Add extensions]
  • The concept of coverage collections could be useful also outside MetOcean domain

WCS as an INSPIRE download service (discussion)

Software support

  • Some existing software has issues, e.g. MapServer 5.x supports only ~6000x6000 px images
  • Software and standards used by workshop participants
    • WCS 1.0.0: Geoserver x.x
    • WCS 1.1.0: MapServer 5.x (FI), 6.4.x (JRC), Geoserver x.x (ES)
    • WCS 2.0.1: Rasdaman 9.0.4 OS (BGS, UK), Geoserver 2.5 (BGS, UK), MapServer, ESRI ? (WCS 2.0.0)
  • [Action] Create overview table of software products available and the supported standards, conformance classes and extensions

WCS standard versions: v1.x vs. v2.0.x

  • In v2.0, the data and service model are separated & coverage model based on GML
  • formally v1.x are deprecated by OGC
  • Too many options in 1.1.x --> no interoperability
  • Decide first what needs to be done then decide whether it can be done with standard versions
  • v1.x legacy systems will not be compatible with v2.0.x systems
  • Version 2.1 is unlikely, since most new features are specified in extensions

INSPIRE WCS profile

  • Which WCS extensions and extension conformance classes are needed for INSPIRE?
  • The profile should be kept to the minimum required for meeting the IR requirements
  • Binding:
    • GET/KVP
    • POST XML (optional)
  • CRS support [Action] Investigate two options:
    • Preferred option: CRS extension (crs+crs-gridded-coverage conf classes) - but to be investigated if this is widely supported by existing software
    • Alternative option: separate endpoints/coverages for each CRS
    • In addition, the Name Type Specifications for CRS (OGC 11-135r2) could be used for naming compound CRS
  • [Action] Illustrate opportunities of additional (non required) extensions

Mapping to INSPIRE "data set"concept

  • Dataset = coverage = spatial object, i.e. Map both GetDataset and GetSpatialObject to GetCoverage operation
  • Separate endpoints for each data set series (recommendation)
  • Need for "coverage collection" extension? (cf. EO profile)
  • Could be left up to data provider to decide what should be mapped to a data set; needs to be practical to be downloaded
  • [Action] Have recommendations in TG, including how to link to dataset (series) metadata
  • For huge coverages, complete download might not make sense... (IR obligation cannot be fulfilled)
  • Map Describe Spatial Object Type operation to DescribeCoverage. "Schema information" is provided through DomainSet and RangeType elements in DescribeCoverageResult
  • What to do with old data – archive or also serve through WCS? (out of scope for TGs)

Updating the Download service TGs

  • Distinguish requirements for SW developers and data providers
  • Distinguish between what needs to go in TGs and what could go into "good practices"
  • TGs could be split up into separate TGs, one for each standard

Use cases

  • Data provision
    • Serve model results (e.g. surfaces and grids) through services
    • Serve multi-dimensional or multi-variable data through services
  • Simple download (incl. trimming and slicing)
    • Request images for a user-defined area (bounding box) (often)
    • Request images for a user-defined time period (rarely)
    • Simple KVP/REST
    • Simple way to download a large area reliably (maybe asynchronously)
    • Extract time series for a small area
  • Advanced download
    • Filters which are not trimming and slicing
      *(Server-side) Advanced analyses (directly accessing the data)
    • Statistical analyses (R)
    • Corridor selection: Calculate the healthiest route, temp along flight corridors
    • Interpolation between point values
    • Aggregations – means, max, … exceedances
    • Time series analysis
  • Visualisation (for mapping)
    • image as is
    • Interpolation of point clouds
    • Reclassification of range values
    • styling as defined by the user
    • selecting a style provided by the server

WCS and data specifications

Discussion:
  • Relevant INSPIRE themes: (at least) OI, EL, GE, AC-MF, OF , SO, LC, ER (GG)
  • INSPIRE coverage schemas
    • Support for INSPIRE coverage schemas in tools
    • Alternative encodings for coverage models could be developed based on "pure" GMLCOV + metadata (including for O&M properties). These would then be implementation models for EL, AC+MF, OF, ...
  • Encoding guidelines for TIFF
    • [Action] Check with Pierre-Yves Curtinot whether mapping GML-TIFF is complete
    • [Action] Compare with geoTIFF coverage encoding extension (OGC 12-100)
  • Support for advanced filtering use cases (e.g. based on coverage metadata) would require WCS processing extension (incl. WCPS language)

View services for coverage data

Options:
  • Use WCS to provide coverage or sub-set thereof as 2d image (1 or 3 bands, pixel values 0-255)
  • Use WMS/WMTS on 2d coverages (covered by View services TG)
  • Use WMS on 2d horizontal slices of higher-dim coverages
    • [Action] Check OGC Discussion paper on WMS for higher-dim coverages
    • Tool support: MapServer with rasdaman community (as backend), others?
  • Use WCS+processing extension

Quality of service

This topic was not discussed

Workshop wrap-up. Next steps, actions. MIG engagement

  • Why to go ahead with WCS work for INSPIRE?
    • Do nothing scenario: Serve coverages through Atom or WFS
    • Many advantages and opportunities by using WCS --> [Action] Write these up
    • Investigate situation & plans of coverage data providers (INSPIRE geoportal, questionnaire?, thematic clusters)
    • Need to have endorsement for action MIWP-7b from MIG-P
  • Actions:
    • Early draft of TG WCS section – based on workshop discussions (Alex, Tim, James)
    • State-of-play tools (JRC)
    • Justification & work plan, set-up sub-group (Michael)
    • Raise view service issues (WCS, SOS) to the MIG-T (Michael)
    • Extend Download service TG to include WCS 2.0 (WCS sub-group/study)
    • OS pilot implementation(s) to illustrate SW feasibility (& feedback)
    • Test SW with different data providers to generate feedback on TG
    • Update D2.9 for provision of O&M data using coverages
    • Feedback on data encodings?
    • OGC INSPIRE application profile for WCS
  • How/who/when?
    • Sub-group?
    • Study?
    • Joined funding for OS --> LocationTech / OSGeo (will probably not be able to do this)

Participants

Peter Baumann
  • E-mail:
  • Affiliation: Jacobs University, Bremen, Germany
  • WCS/coverage experience: editor of OGC coverage standards suite; WCS suite implementation; WCS test bed
  • Motivation: harmonization between OGC & INSPIRE
Jorge Esciu Paradell
  • E-mail:
  • Affiliation: Institut Cartogràfic i Geològic de Catalunya (ICGC) – Regional Mapping Agency of Catalonia, SPAIN.
  • WCS/coverage experience:
    • Development and deployment of WCS providing access to the corporate Digital Elevation Models of my organization (DTM 15 metres / DTM 5 metres) in ICGC.
    • Personal experience in the use of the above-mentioned WCS.
    • Analysis and application of the requirements from the INSPIRE Network Services technical guidelines to evaluate conformity of corporate geoservices.
    • Analysis and application of ISO/OGC geographic information standards in my organization.
  • Motivation: I would be willing to participate in the workshop in order to share common issues and challenges regarding the implementation and use of WCS data (especially for the application to large scale orthoimagery data) with other developers / data providers, discover advantages and drawbacks of other encoding ways for coverage data, as well as gain knowledge about the future evolution of the INSPIRE Download Services technical guidelines and the potential links with O&M. In case of my attendance to the WCS workshop, I would be able to contribute:
    • Showing the experience of my organization regarding the implementation of WCS accessing to elevation data (technical architecture implemented, functional and performance issues experienced, feedback from users).
    • Providing knowledge about the requirements from the INSPIRE Data Specification for the Elevation theme.
Simon Jirka
  • E-mail:
  • Affiliation: 52°North
  • WCS/coverage experience: At 52°North we have undertaken some efforts in investigating the combined usage of WCS and SOS. The idea of these activities was to put an SOS and WCS interface on the same data source and to use the functionalities of both interfaces for those purposes they are best suited for: WCS for serving coverages, and SOS for serving time-variant point data extracted from these coverages.
  • Motivation: After being involved in the design of a proposal how the OGC SOS might be used as an INSPIRE Download service, I would be happy to be involved in the discussions how this can also be achieved for the WCS. My main interests comprise the alignment of the approaches for WCS and SOS and the idea of hybrid approaches combining WCS and SOS to serve different types of data originating from a common data source.
Marie Lambois
  • E-mail:
  • Affiliation: IGN-F
  • Expertise: IGN provides some coverages data (elevation and orthoimagery) that could be served by WCS. At a national level, I am responsible for writing French guidelines on INSPIRE network services implementation. I am also an OGC contributor, involved in some web services SWG and a DGIWG contributor (DGIWG is currently writing a WCS 2.0 profile).
  • Contributions: Provide my knowledge on standards and INSPIRE guidelines.
Jukka Rahkonen
  • E.mail:
  • Affiliation: Information centre of the Ministry of agriculture and forestry, Finland
  • WCS/coverage experience:
    • Administrator of WCS (MapServer) service for aerial photos (>12 TB) since 2008.
    • Administrator of WMS (MapServer) services for +300 layers since 2008.
    • Assisting administrator of WFS-T (GeoServer) services since 2006.
    • Involved in WCS, WMS and WFS server and client development as Program Steering Committee member of GeoServer (2012-) and GDAL (2013-) projects.
Ilkka Rinne
  • E-mail:
  • Affiliation: Chief Technology Officer, Consultant in OGC/INSPIRE implementation technologies
  • WCS/coverage experience: Several years of experience in design and implementation of GML/Coverage data models for meteorological data covering weather radar, ground observation, radiosonde sounding and numerical prediction model data sets; Expert member of the INSPIRE TWG AC-MF; Author of the Annex B of INSPIRE Data Specification framework document D2.9: "Discussion Paper on Out-of-Band Results"; Active member in meteorological coverage related discussions in the OGC (MetOcean DWG); Hand-on experience in implementing gridded data visualizations of numerical meteorological data sets as WMS layers using Open Source software and libraries (Geotools, Geoserver).
  • Motivation: Eager to create more practical solutions for delivering coverage data INSPIRE sets. In good position to share the good solutions to many coverage data providers as an INSPIRE consultant of a commercial spatial web services company.
Olav Peeters
  • E-mail:
  • Affiliation: Belgian Interregional Environment Agency (IRCEL - CELINE)
  • WCS/coverage experience: Limited WCS experience. We do however manage several large coverage datasets (high resolution air quality modelling - both regular and irregular grids) which should ideally also be made available as WCS in the future, but we have not yet found the right occasion for this. Currently I manage a WMS service (Geoserver) of this data.
  • Motivation: The high resolution air quality maps we manage are a perfect test cases for INSPIRE specifications for WCS. Since we have been involved in implementing other INSPIRE downloading and viewing services in the past we have a good idea of what needs to be done for WCS. For us it would also be interesting to exchange ideas about the technical difficulties of serving coverages with experts from other environmental domains.
Tim Duffy
  • E-mail:
  • Affiliation: British Geological Survey
  • WCS/coverage experience: Volunteered to be one of the leads on adding WCS section to downloads services TG many months ago at MIG. Involved with earthserver project and getting WCS up and running for INSPIRE compliant OneGeology inititive. Hva already looked into this and its applicability with colleague James Passmore
  • Motivation: Many annex II and III themes can best have dataset web services expressed in WCS form.
James Passmore
  • eMail:
  • Affiliation: British Geological Survey (BGS)
  • WCS/coverage experience: Actively involved in the EU FP7 EarthServer project (http://www.earthserver.eu/), as part of the BGS lighthouse application to provide access to Terabytes of coverage data through OGC WCS and WCPS services; as part of this activity, filed many tickets to ensure that the software was as conformant as possible to the current INSPIRE download services documentation. As one of the BGS SDI technical experts I have hands-on knowledge of using multiple software (Rasdaman, ArcGIS, MapServer, GeoServer, GeoNetwork) to provision OGC and INSPIRE compliant services.
  • Motivation: Discuss errors/issues in the circulated 'WCS as Candidate INSPIRE Download Service for Coverage Data' document, offer a live demonstration of an INSPIRE compliant WCS 2.0.1 service to the meeting. Harmonization and clarity of download services technical guidelines.
Ian Edwards
  • Email:
  • Affiliation: Met Office
  • WCS Experience: Geospatial specialist developing coverages and WCS services
  • Motivation: The Met Office has led the development of the WCS Met/Ocean profile and we would like to contribute to the development of technical guidelines on the use of WCS for INSPIRE. We would like to share examples of WCS services that we have implemented and demonstrate the use cases that these services address.
Jarle Johan Pedersen
  • Email:
  • Organisation: Norwegian Mapping Authorities, Norway
  • WCS/Coverage experience:
    • Some experience with multispectral data and analysis thereof
    • User of GRASS GIS since 2007
    • User of GDAL since 2010
    • Administrator for WMS (Mapserver) services since 2010
    • Administrator for WCS (Mapserver) service for bathymetry/elevation-models since 2012
    • Administrator for WFS (Deegree) services since 2013
Chris Schubert Lorena Hernandez Alexander Kotsev
  • Email:
  • Organisation: Joint Research Centre
  • WCS/Coverage experience:
  • Motivation: Interest in combining and making different OGC services (such as SOS + WFS + WCS) work together in the context of INSPIRE
Michael Lutz
  • Email:
  • Organisation: Joint Research Centre
  • WCS/Coverage experience: Limited WCS experience; general knowledge of OGC specifications and ISO, INSPIRE and GML coverage data models
  • Motivation: Understand the needs and opportunities of WCS for INSPIRE download services and dependencies with coverage-based data models for INSPIRE Annex II+III data themes
Pascal Derycke Laurent Dubroca

20141014_WCS_Workshop_JRC_Kotsev.pdf (629 KB) Alexander Kotsev, 29 Oct 2014 12:24 pm

20141014_INSPIRE_SOS_Jirka.pdf (497 KB) Alexander Kotsev, 29 Oct 2014 12:24 pm

20141014_INSPIREd-geology_Passmore_Duffy.pdf (1.2 MB) Alexander Kotsev, 29 Oct 2014 12:25 pm

20141014_WCS_Workshop_Olav_Peeters.pdf (243 KB) Alexander Kotsev, 29 Oct 2014 12:28 pm

20141014_WCS_Workshop_IGNF_Lambois.pdf (247 KB) Alexander Kotsev, 29 Oct 2014 12:28 pm

20141014_WCS_WS_ICGC_JEscriu.pdf (169 KB) Alexander Kotsev, 29 Oct 2014 12:28 pm

20141014_MIF_Overview_Lutz.pdf (807 KB) Alexander Kotsev, 29 Oct 2014 12:41 pm

20141014_WCS_2.0_MetOcean_Edwards.pdf (3.85 MB) Michael Lutz, 29 Oct 2014 05:52 pm

20141014_WCS_Intro_Baumann.pdf (3.78 MB) Alexander Kotsev, 30 Oct 2014 04:28 pm

20141015_ElevationDataModel-Coverages_JEscriu.pdf (1.47 MB) Alexander Kotsev, 30 Oct 2014 04:31 pm

20141014_D2.9_coverage_requirements_Rinne.pdf (369 KB) Alexander Kotsev, 30 Oct 2014 04:31 pm

20141014_WCS_experiences_Rahkonen.pdf (163 KB) Alexander Kotsev, 31 Oct 2014 02:47 pm

20141014_WCS_workshop_BGS_Passmore.pdf (656 KB) Michael Lutz, 05 Nov 2014 12:05 pm