David Zeltzer

A survey of glove-based input

Clumsy intermediary devices constrain our interaction with computers and their applications. Glove-based input devices let us apply our manual dexterity to the task. We provide a basis for understanding the field by describing key hand-tracking technologies and applications using glove-based input. The bulk of development in glove-based input has taken place very recently, and not all of it is easily accessible in the literature. We present a cross-section of the field to date. Hand-tracking devices may use the following technologies: position tracking, optical tracking, marker systems, silhouette analysis, magnetic tracking or acoustic tracking. Actual glove technologies on the market include: Sayre glove, MIT LED glove, Digital Data Entry Glove, DataGlove, Dexterous HandMaster, Power Glove, CyberGlove and Space Glove. Various applications of glove technologies include projects into the pursuit of natural interfaces, systems for understanding signed languages, teleoperation and robotic control, computer-based puppetry, and musical performance.<<ETX>>

Pump it up: computer animation of a biomechanically based model of muscle using the finite element method

Muscle is the fundamental “motor” that drives all animal motion. We propose that changes in shape of moving human and animal figures will be accurately reproduced by simulating the muscle action and resulting forces that propel these figures. To test this hypothesis, we developed a novel computational model of skeletal muscle. The geometry and underlying material properties of muscle are captured using the finite element method (FEM). A biomechanical model of muscle action is used to apply non-linear forces to the finite element mesh nodes. We have tried to validate the FEM model by simulating well known muscle experiments and plotting out key quantities. Our results indicate that the twin goals of realistic computer animation and valid biomechanical simulation of muscle can be met using these methods, providing a principled foundation both for animators wishing to create anatomically based characters and biomechanical engineers interested in studying muscle function. CR Categories: 1.3.7 [Computer Graphics]: ThreeDimensional Graphics and Realism—Animation. Additional

Dynamic simulation of autonomous legged locomotion

Accurate simulation of Newtonian mechanics is essential for simulating realistic motion of joined figures. Dynamic simulation requires, however, a large amount of computation when compared to kinematic methods, and the control of dynamic figures can be quite complex. We have implemented an efficient forward dynamic simulation algorithm for articulated figures which has a computational complexity linear in the number of joints. In addition, we present a strategy for the coordination of the locomotion of a six-legged figure - a simulated insect - which has two main components: a gait controller which sequences stepping, and motor programs which control motions of the figure by the application of forces. The simulation is capable of generating gait patterns and walking phenomena observed in nature, and our simulated insect can negotiate planar and uneven terrain in a realistic manner. The motor program techniques should be generally applicable to other control problems.

Making them move: mechanics, control, and animation of articulated figures

Making Them Move: Mechanics, Control, and Animation of Articulated Figures Edited by Norman I. Badler, Brian A. Barsky, and David Zeltzer PART ONE -- INTERACTING WITH ARTICULATED FIGURES Chapter 1 Task-level Graphical Simulation: Abstraction, Representation, and Control David Zeltzer Chapter 2 Composition of Realistic Animation Sequences for Multiple Human Figures Tom Calvert Chapter 3 Animation from Instructions Norman I. Badler, Bonnie L. Webber, Jugal Kalita, and Jeffrey Esakov PART TWO -- ARTIFICIAL AND BIOLOGICAL MECHANISMS FOR MOTOR CONTROL ARTIFICIAL MOTOR PROGRAMS Chapter 4 A Robot that Walks: Emergent Behaviors from a Carefully Evolved Network Rodney A. Brooks BIOLOGICAL MOTOR PROGRAMS Chapter 5 Sensory Elements in Pattern-Generating Networks K.G. Pearson Chapter 6 Motor Programs as Units of Movement Control Douglas E. Young and Richard A. Schmidt Chapter 7 Dynamics and Task-specific Coordinations M.T. Turvey, Elliot Saltzman, and R.C. Schmidt Chapter 8 Dynamic Pattern Generation and Recognition J.A.S. Kelso and A.S. Pandya LEARNING MOTOR PROGRAMS Chapter 9 A Computer System for Movement Schemas Peter H. Greene and Dan Solomon PART THREE -- MOTION CONTROL ALGORITHMS Chapter 10 Constrained Optimization of Articulated Animal Movement in Computer Animation Michael Girard Chapter 11 Goal-directed Animation of Tubular Articulated Figures or How Snakes Play Golf Gavin Miller Chapter 12 Human Body Deformations Using Joint-dependent Local Operators and Finite-Element Theory Nadia Magnenat-Thalmann and Daniel Thalmann PART FOUR -- COMPUTING THE DYNAMICS OF MOTION Chapter 13 Dynamic Experiences Jane Wilhelms Chapter 14 Using Dynamics in Computer Animation: Control and Solution Issues Mark Green Chapter 15 Teleological Modeling Alan H. Barr Appendix A: Video Notes Appendix B: About the Authors Index

Prototyping and design for assembly analysis using multimodal virtual environments

Abstract The goal of this work is to investigate whether estimates of ease of part handling and part insertion can be provided by multimodal simulation using virtual environment (VE) technology, rather than by using conventional table-based methods such as Boothroyd and Dewhurst Charts. The long term goal is to extend cad systems to evaluate and compare alternative designs using Design for Assembly Analysis. A unified physically based model has been developed for modeling dynamic interactions among virtual objects and haptic interactions between the human designer and the virtual objects. This model is augmented with auditory events in a multimodal VE system called the Virtual Environment for Design for Assembly (VEDA). The designer sees a visual representation of the objects, hears collision sounds when objects hit each other and can feel and manipulate the objects through haptic interface devices with force feedback. Currently these models are 2D in order to preserve interactive update rates. Experiments were conducted with human subjects using two-dimensional peg-in-hole apparatus and a VEDA simulation of the same apparatus. The simulation duplicated as well as possible the weight, shape, size, peg-hole clearance, and frictional characteristics of the physical apparatus. The experiments showed that the Multimodal VE is able to replicate experimental results in which increased task completion times correlated with increasing task difficulty (measured as increased friction, increased handling distance combined with decreased peg-hole clearance). However, the Multimodal VE task completion times are approximately two times the physical apparatus completion times. A number of possible factors for this temporal discrepancy have been identified but their effect has not been quantified.

CamDroid: a system for implementing intelligent camera control

In this paper, a method of encapsulation camera tasks into well defined units called “camera modules” is described. Through this encapsulation, camera modules can be programmed and sequenced, and thus can be used as the underlying framework for controlling the virtual camera in the widely disparate types of graphical environments. Two examples of the camera framework are shown: an agent which can film a conversation between two virtual actors and a visual programming language for filming a virtual football game.

Hands-on interaction with virtual environments

In this paper we describe the evolution of a whole-hand interface to our virtual-environment graphical system. We present a set of abstractions that can be used to implement device-independent interfaces for hand measurement devices. Some of these abstractions correspond to known logical device abstractions, while others take further advantage of the richness of expression in the human hand. We describe these abstractions in the context of their use in our development of virtual environments.

Interactive graphics for plastic surgery: a task-level analysis and implementation

We have implemented a system for Computer-Aided Plastic Surgery. Planning plastic surgery procedures is complex because the surgeon needs to stretch and reshape the patient’s skin to replace missing tissue while minimizing distortion of the surrounding tissue. Traditional planning techniques rely on the surgeon’s experience to select among a myriad of possible procedure designs. While mathematica1 techniques for predicting the outcome of surgery have been proposed in the past, these are not in widespread use by surgeons because they require the surgeon to perform manual constructions and geometric calculations. Our system makes the analysis process easier by allowing the surgeon to draw the surgical plan directly on a 3D model of the patient. An automatic mesh generator is used to convert that drawing into a well-formulated problem for finite element analysis.

CINEMA: a system for procedural camera movements

This paper presents a general system for camera movement upon which a wide variety of higher-level methods and applications can be built. In addition to the basic commands for camera placement, a key attribute of the CINEMA system is the ability to inquire information directly about the 3D world through which the camera is moving. With this information high-level procedures can be written that closely correspond to more natural camera specifications. Examples of some high-level procedures are presented. In addition, methods for overcoming deficiencies of this procedural approach are proposed.

Towards an integrated view of 3-D computer animation

To automate character animation and extend it to 3-D we need to create and manipulate three-dimensional models of articulated figures as well as the worlds they will “inhabit”.Abstraction andadaptive motion are key mechanisms for dealing with thedegrees of freedom problem, which refers to the sheer volume of control information necessary for coordinating the motion of an articulated figure when the number of links is large. A three level hierarchy of control modes for animation is proposed:guiding, animator-level, andtask-level systems. Guiding is best suited for specifiying fine details but unsuited for controlling complex motion. Animatorlevel programming is powerful but difficult. Task-level systems give us facile control over complex motions and tasks by trading off explicit control over the details of motion. The integration of the three control levels is discussed.