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
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
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:
- Web Map Service (WMS) -- zoom-and-pan navigation over visual renderings of
- Web Coverage Service (WCS) -- simple, yet scalable retrieval and & on
multi-dimensional coverage offerings
- Web Coverage Processing Service (WCPS) -- ad-hoc filtering and processing on
multi-dimensional coverage sets for navigation, extraction, and analytics
- Web Processing Service (WPS) -- black-boxed algorithms offered over the Web.
- Web Feature Service (WFS) -- download of complete coverages
- Sensor Observation Service (SOS) -- download of complete coverages
In these demos, we only consider services capable of subsetting, processing, and
filtering coverages, as downloading of - typically big - coverages seems inadequate.