Sweepers: Swept User-Defined Tools for Modeling by Deformation

Alexis Angelidis (1) , Geoff Wyvill (1) , Marie-Paule Cani (2)

1 Graphics Lab - Graphics and Vision Research Laboratory
2 EVASION - Virtual environments for animation and image synthesis of natural objects

We present sweepers, a new class of space deforma- tions suitable for interactive virtual sculpture. The artist describes a basic deformation as a path through which a tool is moved. Our tools are simply shapes, subsets of 3D space. So we can use shapes already created as customized tools to make more complex shapes or to simplify the mod- eling process. When a tool is moved it causes a deformation of the working shape along the path of the tool. This is in ac- cordance with a clay modeling metaphor and easy to un- derstand and predict. More complicated deformations are achieved by using several tools simultaneously in the same region. It is desirable that deformations for modeling are `foldover-free', that is parts of deformed space cannot overlap so that the deformations are reversible. There are good intuitive reasons to believe that our deforma- tions are foldover-free but we have not yet completed a proof. We have an ecient formulation for a single tool fol- lowing a simple path (translation, scaling or rotation) and we can demonstrate the eects of multiple tools used si- multaneously. For representing shapes, we present a mesh renement and decimation algorithm that takes advantage of the def- inition of our deformations. The prototype implementa- tion described has been used to create a variety of models quickly and conveniently.

Mots clés: Space deformations; fold-over free; interacive modeling

Domaines: Synthèse d'image et réalité virtuelle [cs.GR]

Alexis Angelidis, Geoff Wyvill, Marie-Paule Cani. Sweepers: Swept User-Defined Tools for Modeling by Deformation. Shape Modeling International, Jun 2004, Genova, Italy. pp.63-73, ⟨10.1109/SMI.2004.1314494⟩. ⟨inria-00537464⟩