[ spatio-temporal coverages | who defines coverages? | OGC Coverage Service Standards ]

About this site

Goal of this site is to showcase standards-based services on Big Earth Data, in particular: spatio-temporal coverages. The service is implemented using the rasdaman Big Array Analytics engine.

Spatio-Temporal Coverages

Coverage data are digital representations of space/time varying phenomena. Examples of such multi-dimensional data include raster grids, like 1-D sensor time series, 2-D satellite imagery, 3-D x/y/t image time series and geoscientific models, 4-D x/y/z/t climate and ocean data sets, but also non-gridded data like point clouds, TINs, and general meshes.

Through Web Services, coverages can be accessed conveniently through the Web Coverage Service (WCS) suite and the Web Coverage Processing Service (WCPS) coverage query language.

Who Defines Coverages?

An abstract definition of coverages is provided by ISO 19123 (which is identical to OGC Abstract Topic 6). A concrete definition of coverages is given by OGC GML 3.2.1 Application Schema - Coverages (nicknamed "GMLCOV") which not only establishes interoperability, but also comes with concrete conformance tests challenging implementations. Don't get confused by the "GML" in the name - GML is but one format for delivery (suitable, e.g., for sensor timeseries), but any other suitable format will do as well, such as GeoTIFF, JPEG2000, NetCDF, etc.

OGC Coverage Service Standards

The main service interface for accessing coverages in a flexible way is the OGC Web Coverage Service 2.0 . WCS is a modular service suite consisting of a Core (mandatory for all implementations) and several optional extensions. Core functionality consists of subsetting (trimming and slicing coverages) while extensions define, e.g., band subsetting, scaling, CRS transformation, encoding, protocols, and raster queries. The latter is represented by the OGC Web Coverage Processing Service (WCPS) Language (see manual + tutorial). WCPS unleashes open, flexible Web access to sensor and observation data archives for navigation, extraction, aggregation, and analysis.

Here is a synopsis of OGC service interface standards for accessing coverages:

In these demos, we only consider services capable of subsetting, processing, and filtering coverages, as downloading of - typically big - coverages seems inadequate.