The Open Geospatial Consortium (OGC) membership has proposed updates to the OGC Abstract Spec Topic 21 - Discrete Global Grid Systems (DGGS) document and is seeking public comment before approval. This version was jointly developed with ISO TC211 and has the same normative content as ISO/DIS 19170-1:2020.
The goal of a DGGS is to enable rapid assembly of spatio-temporal data without the difficulties of working with projected coordinate reference systems and complex geometries. DGGSs represent the Earth (or other planetary bodies) as hierarchical sequences of tessellations, each with global coverage and with progressively finer resolution. Each cell (or zone) in the tessellations has a unique identifier, so that individual observations can be assigned an identifier corresponding to both the position and size of the phenomenon being observed. This means that the resolution and precision of the data capture is inherently part of the stored data; not something that needs to be explained in metadata and therefore potentially overlooked.
Further, DGGS come with a standard set of topological queries that enable rapid data analysis of very large numbers of zones and, by their very nature, are well suited to parallel processing applications at multiple spatial resolutions - a boon for big data processing.
The changes in this revised edition compared to the previous OGC edition include:
- Separation of the DGGS standard into common modules and an extension for Equal Area Earth DGGS;
- Remodelling to incorporate new versions of ISO 19107, ISO 19111 & ISO 19112, and tighter integration with ISO 19115-1;
- Extending the common module to support up to three spatial dimensions and up to one temporal dimension;
- Additional modelling of temporal geometry and temporal reference systems sufficient for spatio-temporal DGGS, introducing the concept of a zone as a region of space-time equivalent to a location or an era;
- Remodelling algebraic functions as spatio-temporal extension of ISO 19107 Query;
- Explicit handling of Dynamic vs Static datums for Equal Area Earth DGGS.
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