The OGC web coverage processing service (WCPS) standard

Imagery is more and more becoming integral part of geo services. More generally, an increasing variety of sensors is generating massive amounts of data whose quantized nature frequently leads to rasterized data structures. Examples include 1-D time series, 2-D imagery, 3-D image time series and x/y/z spatial cubes, and 4-D x/y/z/t spatio-temporal cubes. The massive proliferation of such raster data through a rapidly growing number of services make open, standardized service interfaces increasingly important. Geo service standardization is undertaken by the Open GeoSpatial Consortium (OGC). The core raster service standard is the Web Coverage Service (WCS) which specifies retrieval based on subsetting, scaling, and reprojection. In 2008, OGC has issued a companion standard which adds flexible, open-ended coverage processing capabilities. This Web Coverage Processing Service (WCPS) specifies a coverage processing language allowing clients to send requests of arbitrary complexity for evaluation by the server. This contribution reports on the WCPS standard by giving an introduction to its coverage model and processing language. Further, design rationales are discussed, as well as background and relation to other OGC standards. 1-D to 4-D use case scenarios illustrate intended use and benefits for different communities. Although the paper focuses on conceptual issues, the WCPS reference implementation, PetaScope, is briefly addressed. The author is co-chair of the coverage-related working groups in OGC.