J. Michael Moshell

A two-handed interface for object manipulation in virtual environments

A two-handed direct manipulation VE (virtual environment) interface has been developed as an intuitive manipulation metaphor for graphical objects. A new input device called ChordGloves introduces a simple technique for rapid and repeatable gesture recognition; the Chordgloves emulate a pair of 3-D mice and a keyboard. A drafting table is isomorphically mapped into the VE and provides hand support for 2-D interface techniques, as well as a reference frame for calibrating the mapping between real and virtual worlds. A cursor gravity function is used to grab vertices, edges, or faces and establish precisely aligned differential constraints between objects called anchors. The capability of subjects to translate, rotate, scale, align, and glue objects is tested with a puzzle building task. An approximation of the puzzle task is done in Adobe Illustrator to provide a performance reference. Results and informal user observations as well as topics for future work are presented.

The virtual environment performance assessment battery vepab: Development and evaluation1

The Virtual Environment Performance Assessment Battery (VEPAB) is a set of tasks developed to support research on training applications of virtual environment (VE) technology. VEPAB measures human performance on vision, locomotion, tracking, object manipulation, and reaction time tasks performed in three-dimensional, interactive VEs. It can be used to provide a general orientation for interacting in VEs and to determine both entry level performance and skill acquisition of users. In addition, VEPAB allows comparison of task performance, side effects and aftereffects, and subjective reactions across different VE systems. By providing benchmarks of human performance, VEPAB can promote continuity in training research involving different technologies, separate research facilities, and dissimilar subject populations. This paper describes the development of VEPAB and summarizes the results of two experiments, one to test the sensitivity of the tasks to differences between input control devices and the other to examine practice effects.

Networked virtual environments

The problem of resource bottlenecks is encountered in almost any distributed virtual environment or networked game. Whenever the demand for resources – such as network bandwidth, the graphics pipeline, or processing power – exceeds their availability, the resulting competition for the resources leads to a degradation of the system’s performance. In a typical client-server setup, for example, where the virtual world is managed by a server and replicated by connected clients which visualize the scene, the server must repeatedly transmit update messages to the clients. The computational power needed to select the messages to transmit to each client, or the network bandwidth limitations often allow only a subset of the update messages to be transmitted to the clients; this leads to a performance degradation and an accumulation of errors, e.g. a visual error based on the positional displacement of the moving objects. This thesis presents a scheduling algorithm, developed to manage the objects competing for system resources, that is able to achieve a graceful degradation of the system’s performance, while retaining an output sensitive behavior and being immune to starvation. This algorithm, called Priority Round-Robin (PRR) scheduling, enforces priorities based on a freely definable error metric, trying to minimize the overall error. The output sensitivity is a crucial requirement for the construction of scalable systems, and the freely definable error metric makes it suitable to be employed whenever objects compete for system resources, in client-server and peer-to-peer architectures as well. Therefore Priority Round-Robin scheduling is a substantial contribution to the development of distributed virtual environments and networked online-games.

Modeling soil: realtime dynamic models for soil slippage and manipulation

A physically based model of an object is a mathematical representation of its behavior, which incorporates principles of Newtonian physics. Dynamic soil models are required in animations and realtime interactive simulations in which changes of natural terrain are involved. Analytic methods, based on soil properties and Newtonian physics, are presented in the paper to model soil slippage and soil manipulations. These methods can be used to calculate the evolution of a given soil configuration under the constraint of volume conservation and to simulate excavating activities such as digging, cutting, piling, carrying or dumping soil. Numerical algorithms with linear time and space complexities are also developed to meet the requirement of realtime computer simulation. CR Categories: I.3.7 [Computer Graphics]: Graphics and Realism; I.6.3 [Simulation and Modeling]: applications. Additional

Applying mixed reality to entertainment

The lack of compelling content has relegated many promising entertainment technologies to laboratory curiosities. Although mixed-reality techniques show great potential, the entertainment business is not about technology. To penetrate these huge markets, MR technology must become transparent for the content to have full effect. To achieve this goal, we have devised a framework that lets us integrate concepts from disparate areas such as theme parks, theater, and film into a comprehensive research methodology. We believe that our framework, which has already helped us create content for MR entertainment systems, can provide these benefits to other developers as well.

Shared virtual worlds for education: the ExploreNet experiment

Abstract.ExploreNet is an experimental environment for creating and delivering networked “virtual worlds.” This systems style of user interaction was inspired by the concept of a “habitat” as first articulated in the LucasFilms Habitat system. Players enter and interact in a habitat via their animated alter egos, called “avatars.” Habitats may be created for many purposes, including social interaction, entertainment and education. Our focus has been to facilitate the creation of habitats in which virtual communities of learners and mentors interact. This paper presents details of the current ExploreNet system, including its user interface, the means it provides for creating complex behaviors, details of its implementation, the outcomes of several experiments using this system, and our plans for its natural migration to a World Wide Web-based system.

The virtual academy: a simulated environment for constructionist learning

The Virtual Academy is an educational model based on multiage teams of students and adults working through the Internet to build and use virtual worlds for educational purposes. These collaborations are mediated by a range of tools ranging from electronic mail to hypermedia and video links, and result in the creation of simulation‐based role‐playing adventure games within the ExploreNet software environment ExploreNet is an Internet‐based multimedia, multiuser domain constructed specifically for educational experimentation. This article describes the Virtual Academy Model, the ExploreNet software system, and an experiment conducted in the spring of 1995. The article describes the evolution of features of ExploreNets user interface and their relevance to collaborative work by children.

The Caracol Time Travel Project

Virtual drama is based on the use of a shareable virtual world as a stage setting, withavatars controlled by actors and audience members. The Caracol Time Travel Project wasan experiment in the use of virtual drama for learning about archaeology. Eighteenundergraduate students at the University of Central Florida used a locally developed Java-based system for sharing VRML worlds. They designed and constructed a virtual drama toteach basic concepts of Mesoamerican archaeology and the cultural history of the ancientMaya for middle schools. This paper presents their story design and details of the systemwe developed to support interaction in this shared virtual world. We then discussperformance issues, lessons learned and newer features that we did not have available atthe time. Copyright # 2001 John Wiley & Sons, Ltd.

Tactical simulation in an object-oriented animated graphics environment

Action Graphics (AG) combines the ideas of animated graphics, free-form spreadsheets and object-oriented programming to produce a problem solving and simulation environment.

Back-Leading through character status in interactive storytelling

A key challenge in computer-based interactive narrative is the conflict between user agency and authorial control of the story quality. Valuable lessons can be learned from improvisational and especially interactive theatre, where various narrative and interactive strategies have been developed to engage users in the process of co-creating the story. In this paper, we focus on the use of character status and status shifts. Specifically, we present and illustrate a computational model of status shifts based on the cognitive semantics theory of force dynamics.