Interoperable Coordinate Transformation and Identification of Coordinate Systems

The OpenGIS Consortium (OGC), an industry group, has developed COM, CORBA and Java interface specifications allowing vendors to develop mutually interoperable geospatial software. OGC established the Coordinate Transformation Working Group (CT-WG) in April 1998. The working group developed a Unified Modeling Language object model of coordinate systems (CS) and coordinate transformations (CT) in coordination with ISO/TC211. In June 1999 OGC released this object model as part of a request for proposal. In February 2000 OGC accepted interface specifications (unpublished as of February 2000) drafted in response to this proposal. This paper describes the object model and those specifications. The object model describes a CS as a collection of axes and at least one datum. A recent draft of the object model is available at The specification provides a common way of identifying CS and of accessing CT services that support accuracy calculation. When implemented, these specifications will ease data import; users of compliant applications will import data unaware of its coordinate system. If the application cannot import data in a given coordinate system, a compliant server will transform the coordinates to the native coordinate system. INTRODUCTION The OpenGIS Consortium (OGC) is a non-profit organization that promotes interoperable geoprocessing. The goal is that geospatial applications access data and services using standard interfaces. Clients using standard interfaces need not know much about the server. OGC defines OpenGIS as " transparent access to heterogeneous geodata and geoprocessing resources in a networked environment. The goal of the OpenGIS Project is to provide a comprehensive suite of open interface specifications that enable developers to write interoperating components that provide these capabilities. "