PHYSICALLY-BASED INTERACTIVE CAMERA MOTION CONTROL USING 3D INPUT DEVICES

Russell Turner, Francis Balaguer, Enrico Gobbetti,
Daniel Thalmann

ABSTRACT

The newest three-dimensional input devices, together with high speed graphics workstations, make it possible to interactively specify virtual camera motions for animation in real time. In this paper, we describe how naturalistic interaction and realistic-looking motion can be achieved by using a physicallybased model of the camera's behavior. Our approach is to create an abstract physical model of the camera, using the laws of classical mechanics, which is used to simulate the virtual camera motion in real time in response to force data from the various 3D input devices (e.g. the Spaceball, Polhemus and DataGlove). The behavior of the model is determined by several physical parameters such as mass, moment of inertia, and various friction coefficients which can all be varied interactively, and by constraints on the camera's degrees of freedom which can be simulated by setting certain friction parameters to very high values. This allows us to explore a continuous range of physically-based metaphors for controlling the camera motion. We present the results of experiments with several of these metaphors and contrast them with existing ones.

Keywords: 3D Interaction, Motion Control, Dynamics, Virtual Cameras

1. INTRODUCTION

Specifying virtual camera motion is an important problem in a number of different computer graphics areas. Animation, scientific visualization, CAD and virtual environments all make considerable use of virtual camera motion in a three-dimensional environment (Brooks et al (1986), Baum et al (1990), Magnenat-Thalmann and Thalmann (1986), Shinagawa et al (1990) ). Computer animation in particular, was quick to take advantage of the visual impact (and ease of programming) of complicated camera motions through relatively static scenes. This was, and still is, the basis for much of the commercial computer animations produced. In scientific visualization, CAD, and virtual environments applications, virtual camera motion is often the most important form of three-dimensional interaction (Watson (1989)).

Now, with the existence of graphics workstations able to display complex scenes containing several thousands of polygons at interactive speed, and with the advent of such new interactive devices as the