Making nested rotations convenient for the user

Abstract

Subimage motion in a three-dimensional computer graphic system is much easier for the user to control if the subimage moves the same direction as his hand while he manipulates the control device. The implementation of such coordinated motion of hand and subimage implies modification of the normal procedure for calculating transformations. The convenience of such manipulation also depends on appropriate selection or design of the input device. This paper reviews the relevant attributes of locator devices and presents an approach to selection. It presents the mathematics of transformation nesting and "compensation" to preserve motionsynchrony. Finally, it offers a case history of an interactive graphic system whose human factors were improved by these techniques.