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.