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 3D virtual environment that incorporates both the IEEE 1278 Distributed Interactive Simulation (DIS) application protocol and the IP Multicast network protocol for multi-player simulation over the Internet.

As military budgets shrink, the Department of Defense (DoD) is turning to virtual worlds (VW) to solve problems and address issues that were previously solved by prototype or field exercises. However, there is a critical void of experience in the community on how to build VW systems. The Naval Postgraduate School’s Network Vehicle Simulator (NPSNET) was designed and built to address this need. NPSNET is a populated, networked, interactive, flexible, three dimensional (3D) virtual world system. This dissertation covers the construction and management of the VW in NPSNET. The system, which uses both standard and non-standard network message formats, is fully networked allowing multiple users to interact simultaneously in the VW. Commercial off the shelf (COTS), Silicon Graphics Incorporated (SGI) workstations, hardware was used exclusively in NPSNET to ensure the usefulness and the portability of the system to many DoD commands. The core software architecture presented here is suitable for any VW.

In this paper, we present a formal theory of a behavioral L-system and describe as application a real time structured L-system interpreter. The behavioral L-system is a timed, conditional, stochastic, parametric and environmentally sensitive L-system which allows besides the modeling of plant and fractal development the description and animation of autonomous actors completely defined by production rules. Virtual environment including geometric objects, force fields and sounds and the behaviors of actors can be defined using the same formalism of the behavioral L-systems

(Continue on reverse if necessary and identify by block number) 20. DISTRIBUTION/AVAILABILITY OF ABSTRACT Doctoral Dissertation 01/90 06/93 June 1993 158 Computer Graphics, Simulator, Simulation, Networks, Virtual worlds, Artificial Reality, Synthetic Environments, NPSNET As military budgets shrink, the Department of Defense (DoD) is turning to virtual worlds (VW) to solve problems and address issues that were previously solved by prototype or field exercises. However, there is a critical void of experience in the community on how to build VW systems. The Naval Postgraduate School's Network Vehicle Simulator (NPSNET) was designed and built to address this need. NPSNET is a populated, networked, interactive, flexible, three dimensional (3D) virtual world system. This dissertation covers the construction and management of the VW in NPSNET. The system, which uses both standard and non-standard network message formats, is fully networked allowing multiple users to interact simul...

(Maximum 200 words) 14. SUBJECT TERMS 17. SECURITY CLASSIFICATION OF REPORT 18. SECURITY CLASSIFICATION OF THIS PAGE 19. SECURITY CLASSIFICATION OF ABSTRACT 15. NUMBER OF PAGES 16. PRICE CODE 20. LIMITATION OF ABSTRACT 5. FUNDING NUMBERS i Macedonia, Michael R June 1995 Dissertation Unclassified Unclassified Unlimited Unclassified ANETWORKSOFTWAREARCHITECTUREFORLARGE-SCALE VIRTUAL ENVIRONMENTS (U) Naval Postgraduate School Monterey, CA 93943-5000 The views expressed in this thesis are those of the author and do not reflect the official policy or position of the Department of Defense or the United States Government. Approved for public release; distribution is unlimited. We present a network software architecture for solving the problem of scaling large distributed simulations. The motivation for our effort is to expand the capability of virtual environments to serve large numbers (more than 1,000) of simultaneous users. The fundamental idea of our approach is t...