University of Texas at Austin, August 1993
Andreas Spiegl - Master Thesis

         Physical Modelling Of Non-Rigid Objects
         And Interactive Display Using BSP Trees

In recent years realistic modeling of 3D-objects has become an active
area of computer graphics research.  Early approaches modeled objects
as rigid bodies, a simplification that yields satisfactory results
only in a few special cases.  In order to achieve a realistic
simulation, physical properties allowing deformations of the modeled
object have to be taken into account.

This thesis presents a modeling system and an animation tool designed
to simulate and analyze physical behavior of elastic, 3-dimensional
objects in a realistic fashion.  The modeling system represents
objects in terms of point masses, springs and hinges.  Unlike previous
approaches to this problem, our model imposes no restrictions on an
object's deformation.

The animation tool represents objects as binary space partitioning
trees, a data structure that allows us to efficienty determine surface
visiblity.  Along with a flat-shading color model, every frame of the
animation is rendered in real time.  Each scene can be inspected from
any desired viewpoint, thus providing a tool for exact analysis of
motion and deformation of modeled objects.  An intuitive graphical
user interface supports easy handling.