Discrete Global Grid Systems DWG

Chair(s):

Sabeur, Zoheir (University of Southampton)
Peterson, Perry (Global Grid Systems Inc.)
Purss, Matthew (Geoscience Australia)
Strobl, Peter (Joint Research Centre (JRC))

Group Charter:

Download Charter document

Group Description:

1.    Purpose of Working Group

This Domain Working Group will provide a forum for the discussion of requirements and use cases for standards and the registration of implementations related to Discrete Global Grid Systems (DGGS). The working group will provide a forum for broad discussion of DGGS topics and research activities that are of relevance to various geospatial communities and that may potentially impact on existing, or new, geospatial standards. The working group will aim to increase awareness of the advantages of DGGSs in general, to define the qualities of a DGGS, to make them interoperable – with conventional and other DGGS data sources, and to support activities to standardize operations on them.

 

2.    Problem Statement

Geospatial and geoscientific data have already exceeded the petabyte-scale barrier and are rapidly heading toward the exabyte-scale barrier (and beyond). Converting this massive amount of data into timely information and decision support products is dependent on the capacity of the scientist to rapidly analyze this data in a transparent and repeatable fashion. The challenges of high velocity, high volume (> a terabyte per day) data is requiring those focused on combining and using these large data sources to rethink the way they store data in order to make best use of it. These challenges will only grow as requirements to combine these data sources to produce near-real-time decision support information increases.

 

A new generation of decision-makers are also expecting systems that are not constrained by middle data integrators who usually produce bespoke data products in anticipation of user questions. These decision-makers have grown in sophistication – navigating time and space, mining the web for interesting information, and sharing their insights with others is everyday business. They are always connected; they are experts that demand choices and control over their own experience; and they expect all the information now.

 

However, there is a significant gap between the expectations of this broad user community and the present day reality of using geospatial analysis tools that are based on conventional Geospatial Information System (GIS) technologies. And a solution can only be achieved through the conversion of traditional data archives into standardized data architectures that support parallel processing in distributed and/or high performance compute environments.

 

Well organized data repositories are important, but they must also be interoperable. A common framework is required that can link very large multi-resolution and multi-domain datasets together and to enable the next generation of analytic processes to be applied. The envisaged integration of existing and future data infrastructures thereby puts a strong focus on coordination, harmonization and interoperability of data and services. A solution must be capable of handling multiple, potentially disparate, data streams rather than being explicitly linked to a specific sensor or data type.

 

Such a common framework exists via Discrete Global Grid Systems (DGGS), although DGGS are not yet widely understood or adopted technologies throughout the geospatial community. A DGGS is a form of Earth reference that, unlike conventional coordinate reference systems (which represent the Earth as a continual lattice of points), represent the Earth using a hierarchical tessellation of equal area cells; where each cell is referenced by a globally unique identifier. A key differentiation of DGGS from other GIS technologies is that a DGGS represents the entire curved surface of the Earth rather than a flattened map projected representation. This means that spatial analytics conducted within a DGGS do not need to account for the added distortions created when map projections are applied to data; thus, leading to more efficient and more accurate outcomes. Because each cell of a DGGS represents a uniform spatial unit with a unique reference identifier, a DGGS is able to reduce complex multi-dimensional spatial queries into one-dimensional array processes that enable rapid and accurate computation and integration of data.

 

While conventional coordinate reference systems are designed to facilitate repeatable navigation, a DGGS is designed to ensure a repeatable representation of measurements – observations, interpretations, and events. Every item of information in a DGGS is associated with an area, and spatial resolution is explicit. This is much preferable to tagging an attribute with a latitude and longitude, since it's never clear what area possesses the attribute, or how accurate the measurement of location is. Combining or integrating layers becomes trivial in a DGGS, because items of information are automatically spatially associated with each other. This is much like overlaying information across congruent rasters, and far easier than having to perform overlay using points, lines, and arbitrary areas.

 

Work is currently underway through the OGC to standardize DGGS and to ensure these new technologies can be constructed in a way that facilitates interoperability within and between DGGS implementations. Topic 21 Discrete Global Grid Systems Abstract Specification [OGC 15-104r5] has been adopted as an OGC standard. This Domain Working Group will operate as a forum for the continued discussion of both DGGS research and development and the governance of DGGS related standards.


3.    Charter

The following constitutes the general scope of work for the DGGS DWG.

  1. Discuss emerging issues and topics related to DGGS technologies and standards,
  2. Govern the discussion of requirements and use cases that impact the OGC DGGS standards baseline, and where appropriate task the DGGS SWG to draft specific DGGS implementation standards and protocols/best practice documents,
  3. Engage with the OGC Compliance Program, and other TC Working Groups as necessary, to establish, manage and publish an OGC registry of DGGS specifications and their implementations,
  4. Engage with other OGC working groups on cross-cutting issues related to DGGS,
  5. Engage with other Standards bodies, as necessary, on DGGS related matters (including the establishment of external and/or joint workings groups to draft DGGS relevant standards), and
  6. Advocate the adoption of DGGS technologies through the public, private and academic sectors.

3.1    Charter Members.

The initial membership of the DOMAIN WG will consist of the following members and individuals with extensive education and experience in DOMAIN issues, namely:

 

Name

Affiliation

Matthew B.J. Purss

Geoscience Australia

Robert Gibb

Landcare Research NZ

Faramarz Samavati

University of Calgary

Perry Peterson

PYXIS

Clinton Dow

ESRI

Jin Ben

Zhengzhou Institute of Surveying & Mapping

Peter Strobl

Joint Research Centre

Chris Little

UK Met Office

Ted Habermann

The HDF Group

 

 

 

3.2    Key Activities.

 

The DGGS DWG shall perform the following general activities:

  1. Administer the discussion of requirements and use cases that impact the DGGS standards baseline,
  2. Engage with the OGC Compliance Program, and other TC Working Groups as necessary, to establish and administer a registry of conformant DGGS specifications and their implementations and to govern the registry’s content,
  3. Discuss current and future trends in DGGS research, development and implementation,
  4. Discuss and identify gaps in the DGGS and wider OGC standards baselines where specific interoperable protocols need to be specified,
  5. Develop examples demonstrating the implementation of the DGGS standards baseline, and
  6. Organize, promote, and support test-bed and pilot project activity while it is active to exemplify the value of the standard to content-providers and end-user communities.

3.3    Business Case

Interoperability of spatial data in the era of ‘Big Data’ requires more than well-articulated and standardized data transfer protocols and efficient data formats/compression routines. The global spatial community needs to move away from bulk data transfer to an ecosystem where data queries and compute requests are distributed across numerous large data stores to be processed locally on scalable high performance compute infrastructures. Indeed, with the emergence of cloud computing and HPC infrastructures this requirement is now achievable at scale. Critical in realizing this is the conversion of conventional spatial data stores (both publicly available and private) from bespoke architectures that are tailored to specific and individual processes and workflows to well organized and managed data repositories built using a common spatial framework that can scale from local to global extents.

Well organized data repositories are important, but they must also be interoperable. A common framework is required that can link very large multi-resolution and multi-domain datasets together and to enable the next generation of analytic processes to be applied. The envisaged integration of existing and future data infrastructures thereby puts a strong focus on coordination, harmonization and interoperability of data and services. A solution must be capable of handling multiple, potentially disparate, data streams rather than being explicitly linked to a specific sensor or data type.

DGGS present as a very useful technology that has the potential to fill this gap. However, in the absence of a mature standards baseline governing the specification and implementation of these technologies, these barriers to interoperability will remain. And because both the application of DGGS and the challenges of realizing ‘Big Data Interoperability’ are cross-cutting issues that impact on many existing interoperability and spatial standards it is important for the OGC to create a publicly accessible forum for OGC members and non-members alike to raise and discuss issues and concerns (or even to present and publish   innovations) related to DGGS technologies. This forum should have a wider scope than the DGGS SWG (which will continue to focus on the technical drafting of specific DGGS standards documents and protocols) and will serve as a platform to promote awareness and adoption of DGGS technologies throughout the numerous sectors of the global spatial community.

 

4.    Organizational Approach and Scope of Work

4.1    DGGS DWG Business Goals

The DGGS DWG will establish a set of business goals that form the basis for determining the nature and type of recommendations made to the OGC, framed around the above mentioned business issues.  Some of these business goals include:

  1. Efforts should focus on addressing DGGS issues and problems that result in a net gain for the community,
  2. Minimize incompatible technical distinctions between different DGGS implementations – particularly associated with data interoperability, as this can lead to artificial barriers that limit the potential of all segments of the information community to come together and fully prosper,
  3. Avoid placing artificial technical barriers on use of DGGS hosted data,
  4. Establish the means by which OGC can achieve interoperability and yet preserve the proprietary nature of data sources, and
  5. Define the supporting infrastructure for the community to achieve these goals.

4.2    DGGS DWG: Mission and Role

The mission and role of the DGGS DWG will be to:

  1. Serve as the forum for discussion of requirements and use cases for further development of the DGGS standards suite,
  2. Recommend to the DGGS SWG to elaborate specific DGGS standards documents as required, and
  3. Provide a forum for discussion of topics and issues relevant to DGGS technologies and how they may impact on spatial standards.

4.3    Activities planned for DGGS DWG

Activities currently planned for the DGGS DWG include:

  1. Engage with the OGC Compliance Program, and other TC Working Groups as necessary, to establish a registration system for DGGS specifications and their implementations analogous to the registration system used for Coordinate Reference Systems (CRS),
  2. Investigate the elaboration of extensions to the core OGC DGGS Abstract Specification to define additional functional algorithms and/or schemas that will support interoperability protocols through multi-DGGS processing operations,
  3. Investigate potential additions to the OGC DGGS Abstract Specification and follow-on additions to other OGC standards,
  4. Propose the adoption of a companion ISO DGGS standard based on Topic 21: Discrete Global Grid Systems Abstract Specification, and
  5. The elaboration of the core requirements to specify higher dimensional DGGS as either a subsequent version of this Abstract Specification, or as an extension to the core Abstract Specification.

 

5.    References

1.     Topic 21 Discrete Global Grid Systems Abstract Specification [OGC 15-104r5].