Robust semantics Nature of Data

SWE Common Data Model OGC 08-094r1 Examples Satellite location data can be defined as a vector of 3 components, expressed in the J2000 ECI Cartesian frame, the 1 st component being associated to the X axis, the 2 nd to the Y axis and the 3 rd to the Z axis. Angular velocity data from an Inertial Measurement Unit can be defined as a vector of 3 components, expressed in the plane reference frame for instance ENU defined by local East, North, Up directions, the Euler components being mapped to X, Y, Z respectively. Relative time data can be given with respect to an arbitrary epoch itself positioned in a well defined reference frame such as TAI from the French “Temps Atomique International” = International Atomic Time. Requirement http:www.opengis.netspecSWE2.0reqcoretemporal-frame-defined Req 9. A temporal quantity shall be expressed with respect to a well defined temporal reference frame and this frame shall be specified. Requirement http:www.opengis.netspecSWE2.0reqcorespatial-frame-defined Req 10. A spatial quantity shall be expressed with respect to the axes of a well defined spatial reference frame and this frame shall be specified. The “Time” class detailed in clause 7.2.9 is designed for carrying a temporal reference frame or a time of reference in the case of relative time data. The “Vector” class detailed in clause 7.3.2 is a special type of record used to assign a reference frame to all its child-components. The “Matrix” class defined in clause 7.5.2 allows the definition of higher order tensor quantities. This standard does not impose requirements on the type of reference frames that a standardization target shall support. Standards that are dependent on this specification can and often should however define a minimum set of reference frames that shall be supported by all implementations.

6.4 Data Quality

Quality information can be essential to the data consumer and the SWE Common Data Model provides simple and flexible ways to associate qualitative information with each component of a dataset. Copyright © 2011 Open Geospatial Consortium 15