Interactive deformation of virtual objects with force input
Abstract
This research features a new solid modeling system utilizing force inputs. In this system, a user can interactively deform a virtual 3-D object by applying forces. The actual displacements are computed automatically, rather than specified by the user, by using a hierarchical implementation of the finite element method (FEM). Basing deformations on the concepts of elasticity gives the human a measure of predictability when deciding where to apply forces to the object so that a desired shape would ensue. Though FEM is one of the most powerful tools for computing elastic deformations, the computational burden associated with a straightforward application of FEM would make it too slow for any interactive process on even the fastest workstations. We have therefore developed a hierarchical approach in which FEM is implemented at two different resolutions: a coarse resolution for a three-dimensional calculation of the deformations and, subsequently, a finer resolution for the surface layers of the object for a better (and smoother) delineation of the object shape. For calculations at the finer resolution, we use a plate-theory version of FEM. Other issues explored in this dissertation--important in their own right for interactivity--deal with the design of force-input devices; interpretation of signals produced by the force-input devices with regard to the magnitude and the directions of the forces; user interface and human-computer interactions; representation and output of deformed objects; creation of complex objects from sculpted primitives, etc.
Degree
Ph.D.
Advisors
Kak, Purdue University.
Subject Area
Electrical engineering|Computer science|Mechanical engineering
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