| 3D tele-immersion (3DTI) has the potential of enabling virtual-reality-like interaction among remote people with real-time 3D video. However, today's 3DTI systems still suffer from various performance issues, limiting their broader deployment, due to the enormous demand on temporal (computing) and spatial (networking) resources. Past research focused on system-centric approaches for technical optimization, without taking human users into the loop. We argue that human factors (including user preferences, semantics, limitations, etc.) are an important and integral part of the cyber-physical 3DTI systems, and should not be neglected.;This thesis proposes a novel, comprehensive, human-centric framework for improving the qualities of 3DTI throughout its video function pipeline. We make three major contributions at different phases of the pipeline. At the sending side, we develop an intra-stream data adaptation scheme that reduces level-of-details within each stream without users being aware of it. This human-centric approach exploits limitations of human vision, and excludes details that are imperceptible. It effectively alleviates the data load for computation-intensive operations, thus improves the temporal efficiency of the systems. Yet even with intra-stream data reduced, spatial efficiency is still a problem due to the multi-stream/multi-site nature of 3DTI collaboration. We thus develop an interstream data adaptation scheme at the networking phase to reduce the number of streams with minimal disruption to the visual quality. This human-centric approach prioritizes streams based on user views and excludes less important streams from transmission. It considerably reduces the data load for networking, and thus enhances the spatial resource efficiency. The above two approaches (level-of-details reduction within a video stream and view-based differentiation among streams) work seamlessly together to bring both temporal and spatial resource demands under control, and prove to improve various qualities of the systems. Finally, at the receiving side, we take a holistic approach to study the "quality" concept in 3DTI environments. Our human-centric quality framework focuses on the Quality-of-Experience (QoE) concept that models user's perceptions, emotions, performances, etc. It investigates how the traditional Quality-of-Service (QoS) impacts QoE, and reveals how QoS should be improved for the best user experience. This thesis essentially demonstrates the importance of bringing human-awareness into the design, execution, and evaluation of the complex resource-constrained 3DTI environments. |
