AN OBJECT-ORIENTED METHODOLOGY USING DYNAMIC

VARIABLES FOR ANIMATION AND SCIENTIFIC VISUALIZATION

Russell Turner, Enrico Gobbetti,

Jean-Francis Balaguer, Angelo Mangili,

Daniel Thalmann, Nadia Magnenat Thalmann

ABSTRACT

An object-oriented design is presented for building dynamic three-dimensional applications. This design takes the form of the Fifth Dimension Toolkit consisting of a set of interrelated classes whose instances may be connected together in a variety of ways to form different applications. Animation is obtained by connecting graphical objects to dynamic variables, which are able to change their values over time by responding to events. The Fifth Dimension Toolkit is the core of the Fifth Dimension Project, a research project for animating synthetic actors in their environment. The design philosophy and methodology of the toolkit are also described, as well as some of the implementation issues for the Silicon Graphics Iris 4D workstation.

Keywords: Object-Oriented, Animation, Scientific Visualization, Dynamic Variables.

1. INTRODUCTION

Complex dynamic three-dimensional graphics systems such as task-level animation systems and scientific visualization systems all involve various activities such as surface modeling, rendering, synchronization and motion control. A major problem in the development of such large systems is that they can become very difficult to maintain and extend.

A potential solution to this problem is to replace the traditional structured programming approach and topdown design strategy, with an object-oriented approach, which supports a bottom-up software design process. We use such an approach in the Fifth Dimension Project, a large research project in threedimensional animation and visualization. The main objective of the project is the animation of synthetic actors in their environment, which involves a number of related areas of computer animation and scientific visualization. In particular, the following applications are being developed:

- animation of articulated bodies based on mechanical laws
- vision-based behavioral animation (Renault et al. 1990)
- hair rendering and animation
- intelligent object grasping
- facial animation
- personification in walking models (Boulic et al. 1990)
- synchronization in task-level animation
- deformation of flexible and elastic objects
- cloth animation with detection of collision

To coordinate efforts and allow good communication between the various applications, a toolkit of highlevel dynamic graphical classes, both two and three dimensional, has been constructed. This toolkit, called the Fifth Dimension Toolkit uses a uniformly object-oriented design for all its data structures, resulting in a high degree of integration between various applications.