a) For animation, many 3D systems fix the viewer’s location at a specified distance from the viewing screen. Currently, PictureMaker is one of these. In such systems, the database is moved relative to the viewer.

The set of motions that accomplish any particular view of the world is called its “orientation.” Using the three coordinate axes as references, we can translate (shuffle on a plane) and rotate objects to create new views.

During animation, we change the amounts of these motions. A set of numbers describes orientation: x-trans, y-trans, z-trans, x-rot, y-rot, z-rot. b) A direction of presentation affecting resolution requirements. Horizontal lines become vertical lines when their orientation is rotated by 90 degrees; a pattern of dots appearing to be in horizontal and vertical rows may not appear to be diagonally aligned when its orientation is rotated 45 degrees due to characteristics of the human visual system.