NPSNET: environmental effects for a real-time virtual world battlefield simulator

Abstract

The Computer Science Department at the Naval Postgraduate School in Monterey, California has developed a low-cost real-time interactive simulation system using the Distributed Interactive Simulation (DIS) Protocol, known as NPSNET, that works on commercially available Silicon Graphics IRIS workstations. The DIS protocol has provisions for an environmental effects Protocol Data Unit (PDU), but effects of a changing environment have not been implemented to use it. Furthermore, this lack of environmental effects reduces the realism of the simulations, such as NPSNET, that use the DIS protocol. The challenge in implementing environmental effects such as smoke, dust and the passage of time is to develop a model that users perceive as realistic, but is computationally cheap enough to be used in real-time applications. It is the lack of environmental effects, usable in interactive simulations, that we attempt to solve. This thesis focuses on creating a library of visually realistic environmental effects for NPSNET that includes smoke, flames, clouds, lightning, the passage of time and night observation devices. The algorithms were initially derived from physical models, but were found to be too computationally intensive to be used in a real-time application. Thus, it was necessary to simplify the model by depending mainly on visual realism over physical models in creating the effects presented here. The result is a library of environment effects that are both 'visually accurate' and usable in real-time applications.