Standards Development

Scope

This document specifies fundamental models of tiling schemas that are suitable for binding tiled imagery and gridded data based on ISO 19163-1 and coverage models based on ISO 19123-1.Except grid coverage, the specified tiling schema may also apply to other coverage types, such as point clouds and general meshes, as long as these types are bound to a gridded space and the corresponding tiling schema is described in the gridded space for these data types.

Purpose

Coverage are widely used in the geospatial community and related fields. Over the past two decades, several related standards have been developed by ISO/TC 211, e.g., ISO 19123-x and ISO 19163-x standard series.

ISO 19123-1 defines at a high, implementation-independent level, the notion of coverages as digital representations of space-time varying phenomena, corresponding to the notion of a field in physics. ISO ISO 19123-2 specifies a concrete implementable, conformance-testable coverage structure based on the abstract schema for coverages.ISO 19163-1 specifies logical data structures and the rules for encoding the content components in the structures and ISO 19163-2 specifies implementation schema based on the content models for geographic imagery and gridded thematic data defined in the ISO 19163-1. However, the description for tiling, also known as tessellation, is not included in these documents.

OGC 17-083r4 specifies a two dimensional Tile Matrix Set (TMS) and Tile Set Metadata(TSM), with focus on storage and visualization, rather than online analysis. The extension support for describing 3D or higher dimensions is informatively provided in its annex J. However, the extension are mainly limited to regular partitioning rules, and irregular axis cases require further exploration.

ISO 19170-1 provides DGGS cells as data tiles and utilizes the concepts defined by ISO 19156 to associate observations/spatial data to a DGGS cell. However, it is till not clear how detailed tiling schemas for coverages can be mapped to the DGGS zones, especially the support for higher dimensions.

Without a concrete tiling schema, the specified UML cannot be mapped to the tiling/chunk encodings used in various data formats, such as JPEG2000, GeoTIFF, NetCDF, GMLJP2, and etc.

This document proposes a tiling schema for coverages as a binding between gridded space and gridded data based on ISO 19163-1, and coverage models based on ISO 19123-1. Only tiling in multidimensional hyperrectangles are addressed in this document, since rare data encoding formats support the partitioning in other shapes, such as hexagons, Thiessen polygon, tetrahedron, icosahedron, dodecahedron, and et al.