NPSNET:A Network Software Architecture for LargeScale Virtual Environments

Abstract

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.

Coping with inconsistency due to network delays in collaborative virtual environments

“…In particular, presentation inconsistencies arise due to the lack of global serialisation, which, however, promotes interaction consistency. When working to reduce inconsistency, prediction heuristics of user behaviour can be used to guess the future development of the world in order that events likely to happen could be executed before being received, like in the case of the dead-reckoning mechanism adopted by NPSNET [15]. An example of inconsistency resolution is when two users perform contrasting manipulations on an object, and the system must decide which set of actions to keep and which set of actions to discard, or how to combine them [ 111.…”

Analyse de techniques de coopération en environnements virtuels 3D

“…En distribué répliqué, chaque entité évolue indépendamment, mais l'état de chaque entité doit rester le même sur chaque site au fil du temps ; cela est assuré par le calcul de l'évolution de chaque entité dont l'avancement est basé sur les tics d'une horloge globale. En distribué hybride, deux cas sont possibles : soit un miroir fait suivre les valeurs des sorties d'un référentiel (voir OpenMASK), soit un miroir est un objet qui calcule par lui-même les valeurs de sortie tant que ses propres calculs ne s'écartent pas trop des valeurs calculées par le référentiel (voir NPSNET (Macedonia et al, 1994)). Cette technique s'appelle du dead-reckoning (Gossweiler et al, 1994) et s'emploie notamment pour du calcul de trajectoires.…”

The H-N2N framework: towards providing interperception in massive applications

“…Several communication architectures have been proposed considering the LS-CVE problem. One can mention NPSNET-4, DIVE, MR. TOOLKIT, BRICKNET, MASSIVE, and VELVET [7,11,16,20,25,26] amongst others. Comparison of several of such architectures has been performed based on aspects related to visualization [6], information, process and user distribution [6], and network communication [15].…”