rick@hanauma (Richard Ottolini) (08/19/88)
There was a nice study of the user interface problem in the 1988 SIGGRAPH proceedings (Computer Graphics, v.22, n.4, p.121) by Chen et al. "A Study in Interactive 3-D Rotation Using 2-D Control Devices. They studied four types of controlers: (1) separate x,y,z sliders (e.g. scroll-bars) (2) overlapping sliders: rendered as a 9-square. The interior cross controls x and y. The corners control z. (3) continuous xy + z: one mouse state gives continous xy rotation and another controls z. (4) virtual sphere (trackball): rendered as a circle. As generally expected #1 and #2 make axial rotations easier while #3 and #4 make non-axial rotations easier. (I'd put one of each in my application then.)