Coordinate Systems and Transformations

PHIGS is useful for displaying geometric data from a variety of sources because it allows the user to define an object in whatever coordinate space is most convenient. An object may be defined in angstrom units, inches, meters, light years, or any system that suits the application. The units of measure chosen are defined within a modeling coordinate system using the applicable measurements. PHIGS transforms the objects defined within the modeling coordinate system to physical locations on the graphics output device. These locations are within the device coordinate system. The process of conversion between the user-defined modeling coordinate system to the device coordinate system is known as the transformation pipeline.