Traditionally, muti-screen immersive systems have relied upon dedicated high-end shared memory graphics workstations or supercomputers to generate interactive virtual environments. These multi-screen immersive systems typically require one or two video outputs for each screen and simultaneously utilize several interaction devices. In recent years this trend of almost exclusively using high-end systems has started to change as commodity hardware has become a viable alternative to high-end systems.

Current technologies have empowered PC-based systems with high-quality graphics hardware, significant amount of memory and computing power, as well as support for many external devices. Their application to virtual reality applications is motivated by the dramatic cost decrease they represent and by the wide range of options and availability. To drive a multi-screen immersive environment we need multiple commodity systems working as a single unit, that is, a tightly synchronized cluster. The challenge is that, although the base technology is standard off-the-shelf technology, there is a lack of software for weaving together the cluster into a platform that supports the creation of virtual environments. Furthermore, there is an even greater lack of software that can allow existing virtual environment designed for high-end system to transparently migrate to a cluster.

This document presents ClusterJuggler, an extension to the VR Juggler architecture which allows an application to transparently run on a cluster of comodity PC's. The main goals of ClusterJuggler are to allow the cluster software to adapt to the particular hardware configuration of the virtual reality system, to provide application portability and scalability from high-end to commodity by hiding the clustering from developers, and to allow users to customize the clustering methods being used.