WCS validation

The WCS is validated when an object is read in or written to a file. However, this happens transparently to the end user and knowing the details of the validation machinery is not necessary to use or construct a WCS object.

GWCS uses the Advanced Scientific Data Format (ASDF) to serialize and deserialize GWCS objects (including transformations and frames) and to provide validation that the serialization is correct. ASDF makes use of abstract data type definitions called schemas. The serialization and deserialization happens in classes, referred to as converters defined in gwcs.converters.* modules. Most of the schemas available for the WCS object, coordinate frames and some WCS specific transforms live in the asdf-wcs-schemas package.

Packages using GWCS may create their own transforms and schemas and register them as an Asdf Extension. If those are of general use, it is recommended they be included in asdf-astropy.