Paul T. Barham

Npsnet: A network software architecture for largescale virtual environments

This paper explores the issues involved in designing and developing network software architectures for large-scale virtual environments. We present our ideas in the context of NPSNET-IV, the first 3-D virtual environment that incorporates both the IEEE 1278 distributed interactive simulation (DIS) application protocol and the IP multicast network protocol for multiplayer simulation over the Internet.

NPSNET: a multi-player 3D virtual environment over the Internet

in the Proceedings of the 1995 Symposium on Interactive 3D Graphics, 9 - 12 April 1995, Monterey, California.

Insertion of an articulated human into a networked virtual environment

Most distributed interactive simulation (DIS) technology demonstrated in recent years has focused on vehicle interaction. The dismounted infantryman-the individual soldier-has been largely ignored or represented by static models. In six weeks of development, the Naval Postgraduate School, SARCOS Inc., and University of Pennsylvania, under Army Research Laboratory sponsorship, demonstrated the insertion of a fully articulated human figure into a DIS environment. This paper describes the system architecture.<<ETX>>

Npsnet and the naval postgraduate school graphics and video laboratory

The Naval Postgraduate School Networked Vehicle Simulator IV (NPSNET-IV) is a low-cost, student-written, real-time networked vehicle simulator that runs on commercial, off-the-shelf workstations (the Silicon Graphics IRIS family of computers). NPSNET-IV has been developed at the Naval Postgraduate Schools (NPS) Department of Computer Science in the Graphics and Video Laboratory. It utilizes Simulation Network (SIMNET) databases and SIMNET and Distributed Interactive Simulation (DIS) networking formats. The DIS networking format is flexible enough to allow multiple players to game over the Internet. The availability of NPSNET-IV lowers the entry costs of researchers wanting to work with SIMNET, DIS, and follow-on systems. Without the contributions of the departments M.S. and Ph.D. candidates, the NPSNET project would be impossible to maintain and continue. The diversity of their interests accounts for the broad range of research areas within the project.

Humans in large-scale, networked virtual environments

This paper examines the representation of humans in large-scale, networked virtual environments. Previous work done in this field is summarized, and existing problems with rendering, articulating, and networking numerous human figures in real time are explained. We have developed a system that integrates together some well-known solutions along with new ideas. Models with multiple level of details, body-tracking technology and animation libraries to specify joint angles, efficient group representations to describe multiple humans, and hierarchical network protocols have been successfully employed to increase the number of humans represented, system performance, and user interactivity. The resulting system immerses participants effectively and has numerous useful applications.

The high level architecture

The High Level Architecture (HLA) provides a framework for building large-scale, distributed virtual worlds. HLA provides a standard approach for designing and implementing shared synthetic environments without restricting the developer to a particular programming language, computer architecture or operating system. It enables the developer to define and utilize any data content or format desired to communicate shared information between distributed simulations. HLA consists of three items: a set of rules for building and executing distributed simulations, an interface specification for the Run-Time Infrastructure (RTI) to provide certain services for data sharing and coordination between these simulations, and a standard Object Model Template (OMT) format for describing the data and interactions to be shared between these simulations. HLA was developed by a combined industry and government team in order to increase reusability and interoperability between heterogeneous simulations with diverse requirements. HIA is being proposed and considered as an industry standard architecture by the Institute of Electrical and Electronics Engineers, Inc. (IEEE) and has already been adopted by the Object Management Group (OMG) as the Facility for Distributed Simulation Systems and the United States Department of Defense (DoD) as a required standard for all DoD simulations. HLA is also being used in other countries and is being considered as a simulation standard internationally by the North Atlantic Treaty Organization (NATO). HLA is an architecture or a framework for building distributed simulations. As such, a virtual world (VW) developer is free to design and execute a particular implementation within the guidelines of the framework. The developer can use HLA with any programming language, any hardware platform, and any operating system running with any type of computer network. If an RTI does not yet exist for a given configuration, one can be written that conforms to the HIA interface specification. HLA, as an architecture, does not require the use of a particular RTI implementation nor does it limit the scope of a virtual world application. The software structure itself has no scalability issues; however limits may exist in a particular RTI implementation. Currlently, the only existing RTI implementation available is from the DoD; however, several US. and foreign companies are developing commercially available RTIs. The requirement for anyone developing an official RTI is that the complete HLA interface specification must be implemented (i.e., you cannot partially implement an official HLA RTI). The current RTI (and other HLA-related) software is available for download from the World Wide Web HLA home page (hla.dmso.mi1). The current DoD RTI (v1.3) implementation provides language bindings for C++, Ada95, Corba and Java and is available to support Solaris, IRE, AM, HP-UX, Windows NT and Linux operating systems. The Simulation Interoperability and Standards Organization, Inc. I:SISO) and the Defense Modeling and Simulation Office (DMSO) support email, electronic conferences and training programs for promoting HLA information interchange. Reality by Design (RBD) has been actively using the HLA to build VW applications for two years. Our efforts have involved developing cross-platform applications, most with entertainment potential. Using HLA on low-cost, commercial off-the-shelf (COTS) personal

The NPSNET Sound Cube

This paper describes the implementation of the sound system used to generate aural cues for use in the distributed virtual environment of NPSNET. This sound system is called the NPSNET-3D Sound Server. It is a MIDI-based loudspeaker system consisting of commercial, off-the-shelf equipment. This sound system currently generates 2-D aural cues via four speakers, but is designed for the potential generation of 3-D aural cues via a cube conguration of eight speakers.