2841	 Designing Surfaces in -D	 An experimental system for computer-aided design of free-form surfaces in three dimensions is described. The surfaces are represented in the system as parametric basis splines. The principal features of the system are the surfaces are rendered as isoparametric line drawings on a head-mounted display and they are designed with the aid of a three-dimensional wand which allows -D movements of the points controlling the shapes of the surfaces all of the interactions with the surfaces are in real-time and the mathematical formulations used assume no knowledge of them by the user of the system. Also examined are some of the features that should be part of a practical -D system for designing space-forms. real-time graphics computer-aided design picture processing B-splines -D displays
