Raymond L. Plante
National Center for Supercomputing Applications
University of Illinois
405 North Mathews Ave.
Urbana, IL 61801, USA
horizon@ncsa.uiuc.edu
When exploring scientific data with a data visualization tool, scientists are usually more interested where the data resides in physical or conceptual space than its position within some data array. Such a space, the data's domain, is often referred to as the data's World Coordinate System. This document describes how the Horizon Image Browser Java Package supports the mapping between a datum's position in a dataset and its position within its World Coordinate System. Because the parameters describing a coordinate system can be considered as metadata of the system, this document presents the support for world coordinates as a case study in the use of metadata within Horizon, beginning with a general description of Horizon's metadata model. This model allows data objects to conveniently carry with them a description of its data, allowing other objects to properly interpret the data. In the case of world coordinate systems, a world coordinate system object can therefore know how to determine a datum's coordinate position and even display that position in its conventional, application-specific format.