Enabling multi-party 3D tele-immersive environments with ViewCast

Abstract

Three-dimensional tele-immersive (3DTI) environments have great potential to promote collaborative work among geographically distributed users. However, most existing 3DTI systems only work with two sites due to the huge demand of resources and the lack of a simple yet powerful networking model to handle connectivity, scalability, and quality-of-service (QoS) guarantees. In this article, we explore the design space from the angle of multi-stream management to enable multi-party 3DTI communication. Multiple correlated 3D video streams are employed to provide a comprehensive representation of the physical scene in each 3DTI environment, and are rendered together to establish a common cyberspace among all participating 3DTI environments. The existence of multi-stream correlation provides the unique opportunity for new approaches in QoS provisioning. Previous work mostly concentrated on compression and adaptation techniques on the per-stream basis while ignoring the application layer semantics and the coordination required among streams. We propose an innovative and generalized ViewCast model to coordinate the multi-stream content dissemination over an overlay network. ViewCast leverages view semantics in 3D free-viewpoint video systems to fill the gap between high-level user interest and low-level stream management. In ViewCast, only the view information is specified by the user/application, while the underlying control dynamically performs stream differentiation, selection, coordination, and dissemination. We present the details of ViewCast and evaluate it through both simulation and 3DTI sessions among tele-immersive environments residing in different institutes across the Internet2. Our experimental results demonstrate the implementation feasibility and performance enhancement of ViewCast in supporting multi-party 3DTI collaboration.