On the Geometry of Low Degree-of-Freedom Digital Clay Human-Computer Interface Devices

Digital clay represents a new type of 3-D human-computer interface device that enables tactile and haptic interactions. The digital clay surface is computer controlled and can be commanded to acquire a wide variety of desired shapes, or be deformed by the user in a manner similar to that of real clay. In this paper, we present the ideas underlying digital clay and an example design of a digital clay device meant for generalpurpose modeling. We also introduce the concept of low degree-of-freedom digital clay devices, in which the clay surface can acquire a limited range of shapes, for example, to describe the shapes of automotive front-ends. Each degree of freedom moves a region of the clay surface through a range of predefined shapes. We investigate geometric modeling techniques for defining the ranges of shapes and relate the shapes to forward and inverse kinematics of the deformable structures that control surface shape. To illustrate the application of the digital clay concept, an example low degreeof-freedom clay device for modeling automotive front ends is presented and discussed. 1 DIGITAL CLAY CONCEPTS AND CONTEXT Shape is a key element in successful communication, interpretation, and understanding of complex data in virtually every area of engineering, art, science, and medicine. In recent years, the communication of both form and complex data has been greatly enhanced by visualization technologies.

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