With the advent of 3D humanoid reconstruction techniques, using a realistic 3D human avatar in a serious game has become popular. This realistic representation in the virtual environment could be achieved using a single low-cost RGB-D camera such as Kinect. However, properly setting up such a camera system for high-quality rendering can be challenging due to the relatively restricted in-home environment. In this paper, we address the challenge of finding optimized camera setup guidelines for an in-home first-person perspective mixed reality (MR) gaming system. We use an MR system with personalized humanoids to simulate the texture reconstruction for a user under a specific camera configuration. Then, a derivative-free optimization is leveraged as a black box approach to search for the optimized camera setup through iterative simulation. We also introduce a novel skeleton-based calibration to address the effects of physically varying the camera's position. For evaluation, two experiments are carried out to evaluate the correctness and effectiveness of the proposed calibration. Furthermore, we conduct a case study using simulation-based optimization for reconstructing lower limb amputees. This work can potentially help locate a proper camera setup for an MR system within the constraints of an in-home environment.

With the rapid growth of online video viewing, the quality of experience for users become a critical factor in the video streaming service to attract users and increase their adherence. Multi-side parallel downloading, which requests video segments from various low-cost data nodes simultaneously, could be a strategy to reduce the latency and improve the experience. However, the communication between such data nodes might not be as reliable as a conventional dedicated server. In such a network, the random loss events may bias the loss-based congestion control. Accordingly, this work incorporates a reevaluation mechanism into the CUBIC congestion avoidance state to correct the underestimation of the congestion window. In the experiment, we analyzed the round-trip time pattern and the transmission speed of CUBIC against our modification via network simulation with various loss rates. Our result shows that reevaluation helps to recover the congestion window and to improve the transmission speed in the extremely high-loss network. The derived insight may benefit the future improvement of loss-based congestion control. This paper presents one of the winning team's strategies in the MMSys23 Grand Challenge. The submitted code can be found on GitHub.1.

Head-Mounted Devices (HMDs) have become popular for home-based immersive gaming. However, using lower limb motion in the immersive virtual environment is still restricted. This work introduces an RGB-D camera-based motion capture system alongside a standalone HMD for Home-based Immersive Lower Limbs Exergame Systems (HILLES) in a seated pose. With the advance of neural network models, camera-based 3D body tracking accuracy is increasing. Nevertheless, the high demand for computing resources on model inference may compromise the game engine's performance. Accordingly, HILLES applies a distributed architecture to leverage the resources effectively. The system performances, such as frames per second and latency, are compared with a centralized system. For an immersive exergame, a pet walking around could raise safety issues. Hence, we also showcase that the camera system can provide an additional safety feature by combining an object detection model. Besides, another challenge in games focusing on lower limb interactions is the safe reachability of different virtual objects from a seated pose. Accordingly, in the user study, a stomping game with two reachability enhancements, including leg extension and seated navigation, is implemented based on the HILLES to evaluate and explore the gaming experience. The result shows that the system motivates the leg exercise, and the added enhancements may adjust the game difficulty. However, the enhancements may also distract users from focusing on leg exertion. The derived insight could benefit the lower limb exergame design in the future.

Phantom pain is a chronic pain that is experienced as a vivid sensation stemming from the missing limb. From traditional mirror box to virtual reality-based approaches, a wide spectrum of treatments using mimic feedback of the amputated limb have been developed for alleviating phantom limb pain. In our previous work, Mixed reality-based framework for MAnaging Phantom Pain (Mr.MAPP) was presented and used to generate a virtual phantom upper limb, in real time, to manage the phantom pain. However, amputation of the lower limb is more common than that of the upper limb. Hence, in this paper, on top of demonstrating the reproducibility of the Mr.MAPP framework for upper limb, we extend it to manage lower limb phantom pain as well. Unlike an upper limb amputee, a patient with lower limb amputated is constrained to perform the training procedure in a sitting posture. Accordingly, virtual training games are designed for lower limb exercises with sitting posture such as knee flexion and extension, ankle dorsiflexion and tandem coordinated movement. Finally, the technical details of the system setup for playing the training games are introduced.