Networked virtual environments (NVEs) have become a major trend in distributed computing, mainly due to the enormous popularity of multi-player online games in the entertainment industry. Nowadays, NVE systems are considered as the supporting technology for many networked and virtual organizations (NVO) (Singhal & Zyda, 1999), especially to those classified within the field of computer supported cooperative work (CSCW), where networked computer can be seen as a standard to provide the technological means to support the team design (Ott & Nastansky, 1997). These highly interactive systems simulate a virtual world where multiple users share the same scenario. The system renders the images of the virtual world that each user would see if he was located at that point in the virtual environment. Each user is represented in the shared virtual environment by an entity called avatar, whose state is controlled by the user through the client computer. Hundreds and even thousands of client computers can be simultaneously connected to the NVE system through different networks, and even through the Internet. NVE systems are currently used in many different applications (Singhal & Zyda, 1999) such as civil and military distributed training (Miller & Thorpe, 1995), collaborative design (Salles, Galli, Almeida et al., 1997) and e-learning (Bouras, Fotakis, & Philopoulos, 1998). Nevertheless, the most extended example of NVE systems are commercial multi-player online game (MOG) environments. These systems use the same simulation techniques that NVE systems do, and they are predicted to make up over 25 percent of local area network (LAN) traffic by 2010 (McCreary & Claffy, 2000).
A spatial publish subscribe overlay for massively multiuser virtual environments