Virtual Clay Modeling using Adaptive Distance Fields

This paper describes an approach for the parametrization and modeling of objects represented by adaptive distance fields (ADFs). ADFs support the construction of powerful solid modeling tools. They can represent surfaces of arbitrary and even changing topology, while providing a more intuitive user interface than control-point based structures such as B-splines. Using the octree structure, an adaptively refined quadrilateral mesh is constructed that is topologically equivalent to the surface. The mesh is then projected onto the surface using multiple projection and smoothing steps. The resulting mesh serves as the ``interface'' for interactive modeling operations and high-quality rendering

Modeling and parameter estimation of rheological objects for simultaneous reproduction of force and deformation

Abstract-Many deformable objects in our living life demonstrate rheological behaviors, such as human organs and tissues, clays and various food products. Rheological objects include both elastic and plastic properties. Due to the presence of residual (permanent) deformation, it is difficult to model rheological objects, especially to reproduce both force and residual deformation simultaneously. In this paper, a series of physical models was investigated for simulating rheological behaviors. Generalized formulations of the constitutive laws were derived for serial and parallel physical models, respectively. We found that the serial models are appropriate for formulating strain, whereas the parallel models allow a convenient calculation of stress. Analytical expressions of force and residual deformation were then derived for generalized parallel models. Theoretical discussions suggested the difficulty to reproduce both force and deformation simultaneously using linear physical models. A 2D FE (finite element) model was then formulated and an efficient method for estimating physical parameters were proposed by taking the advantages of analytical force expressions. Experimental results with commercial clay and Japanese sweets material were presented to validate our modeling and parameter estimation methods. A dual-moduli viscous element was also introduced to improve our FE model for reproducing rheological force and deformation simultaneously