Lawrence Koved

Interactive simulation in a multi-person virtual world

A multi-user Virtual World has been implemented combining a flexible-object simulator with a multisensory user interface, including hand motion and gestures, speech input and output, sound output, and 3-D stereoscopic graphics with head-motion parallax. The implementation is based on a distributed client/server architecture with a centralized Dialogue Manager. The simulator is inserted into the Virtual World as a server. A discipline for writing interaction dialogues provides a clear conceptual hierarchy and the encapsulation of state. This hierarchy facilitates the creation of alternative interaction scenarios and shared multiuser environment.

An architecture for virtual worlds

This paper presents a system architecture for creating interactive, multisensory, three-dimensional environments called virtual worlds. The architecture specifically addresses the requirements of virtual worlds for high performance, flexibility, and coordination of concurrent events. Performance is enhanced by a distributed client/server system structure and by efficient overlap of processing time and input/output delay. All processes communicate via asynchronous messages. The functional partitioning of a virtual world requires relatively low bandwidth among the individual processes and the system can be implemented over a conventional local-area network. A key element of this architecture is a central, event-driven dialogue manager that coordinates concurrent input and output events. The dialogue manager provides a clear separation of the interaction techniques from the content of the virtual world as defined by the application. The system is flexible and easily reconfigurable. An interaction technique can be readily changed or replaced because each interaction device is modularized into a separate server and each interaction modality into a separate subdialogue. Subdialogues can be loaded and dropped dynamically, enabling input/output device remapping and the selection of interaction techniques while a virtual world is running. As an initial test of this architecture we have implemented a virtual world for interacting with data from a computational fluid dynamics simulation.

A toolkit for developing multi-user, distributed virtual environments

The design and operation of the Virtual Reality Distributed Environment and Construction Kit (VR-DECK) toolkit developed at IBM Research is reviewed. It provides a designer with a development environment while supporting distributed computing, multi-user capability, and a variety of I/O devices. Virtual worlds are built as collections of modules which communicate via events. Extensive run-time support in the form of extensive C++ class libraries insulates the application designer from the low-level system details such as networking, inter-module data transport, event queuing and matching, and I/O device communication. A library of pre-defined modules is provided for commonly used functions and devices. An X Window System graphical user interface is provided for aggregating modules into applications. The system enables a developer to focus on the design of the application rather than on systems and integration issues.<<ETX>>

Dialogue structures for virtual worlds

We describe a software architecture for virtual worlds, built on a base of multiple processes communicating through a central event-driven user interface management system. The virtual worlds behavior is specified by a dialogue composed of modular subdialogues or rule sets. In order to achieve high flexibility, device remappability and reusability, the rule sets should be written as independent modules, each encapsulating its own state. Each should be designed according to its purpose in a conceptual hierarchy: it can transform a specific device into a generic device, or transform a generic device into an interaction technique, or, at the top level, map interaction techniques to actions.

Design for interactive performance in a virtual laboratory

In recent years, a number of research groups have implemented various versions of virtual world concept [2, 4, 6, 7]. A common thread among these virtual worlds is a direct manipulation user interface paradigm based on a glove device with the position and orientation of the hand registered by a tracking device. To explore this paradigm, a new project at IBM Research was started in 1989 to build a virtual laboratory for scientists and engineers. Our first step is to integrate the glove and space tracking devices with the real time graphics on a graphics superworkstation. A simple bouncing ball virtual world has been created to test underlying software and fine tune interactive performance.Our initial emphasis is placed on understanding the limitations of various system components and getting the best interactive performance from the system. With current state of technology, the glove and tracking devices can generate much more data than the graphics update process can utilize. Both the rendering process and the processes handling the device serial ports are CPU intensive. Our first design problem is how to distribute the processing and match the incoming data rates of input devices with the update rate of the graphics. After a new position from the tracker is received by the graphics, it is displayed only at the next frame update time giving the appearance that the hand image always lags behind the motion of the real hand. Our second design problem is to use techniques to compensate for this inherent lag time. This abstract describes the specific approaches we use to solve these problems and some useful insight gained in experimenting with lag time reduction by position prediction.