Varuna De Silva

Visual Attention Model Aided Non-Uniform Asymmetric Coding of Stereoscopic Video

Owing to its wide-interoperability, stereoscopic 3D video format in High Definition (HD) is a popular choice for 3D entertainment media distribution. However, the delivery over bandwidth constrained networks exhibits challenges in terms of intermittent congestions in the network traffic, which enforce the delivery system to perform perception-aware coding to save bandwidth. In the scope of stereoscopic 3D video, asymmetric quality adaptation has proved to be an effective method in terms of maintaining the perceived quality while reducing the required transmission bandwidth. On the other hand, Region-Of-Interest (ROI) based coding in accordance with the visual attention cues, which offers non-uniform quality assignment to regions of different saliency levels has not been widely studied in combination with asymmetric coding of stereoscopic 3D video. In this work, the effectiveness of using visual attention aided non-uniform asymmetric 3D video coding is explored. The importance of incorporating compression artefacts in the formulation of visual attention model is also revealed. The discussions in this paper are based on a comprehensive subjective test with 8 stereoscopic video sequences of different spatial and temporal characteristics at different conditions.

Robust Fusion of LiDAR and Wide-Angle Camera Data for Autonomous Mobile Robots

Autonomous robots that assist humans in day to day living tasks are becoming increasingly popular. Autonomous mobile robots operate by sensing and perceiving their surrounding environment to make accurate driving decisions. A combination of several different sensors such as LiDAR, radar, ultrasound sensors and cameras are utilized to sense the surrounding environment of autonomous vehicles. These heterogeneous sensors simultaneously capture various physical attributes of the environment. Such multimodality and redundancy of sensing need to be positively utilized for reliable and consistent perception of the environment through sensor data fusion. However, these multimodal sensor data streams are different from each other in many ways, such as temporal and spatial resolution, data format, and geometric alignment. For the subsequent perception algorithms to utilize the diversity offered by multimodal sensing, the data streams need to be spatially, geometrically and temporally aligned with each other. In this paper, we address the problem of fusing the outputs of a Light Detection and Ranging (LiDAR) scanner and a wide-angle monocular image sensor for free space detection. The outputs of LiDAR scanner and the image sensor are of different spatial resolutions and need to be aligned with each other. A geometrical model is used to spatially align the two sensor outputs, followed by a Gaussian Process (GP) regression-based resolution matching algorithm to interpolate the missing data with quantifiable uncertainty. The results indicate that the proposed sensor data fusion framework significantly aids the subsequent perception steps, as illustrated by the performance improvement of a uncertainty aware free space detection algorithm.

Application of Genetic and Greedy Algorithms for Power Efficiency in Adaptive Sub-channel and Bit Allocation

Energy consumption has attracted significant attention by the research community in response to the green initiatives pertaining to electronic equipment and devices. This is especially applicable to wireless environments since the trend of adopting wireless technologies is on the increase. Hence, in this paper we suggest a method for wireless communications to minimize the total power required for transmission. The method considers sub-channel and bit allocation in orthogonal frequency division multiplexing systems for a multiuser scenario. The problem is addressed by exploiting genetic and greedy algorithms mutually to attain minimum power allocation among several users. Through simulation, the proposed method is shown to outperform static allocation methods with an average of 37.20% less required power. It is also shown that the more required bitrate by users the more power saving is achieved.

Player Tracking Data Analytics as a Tool for Physical Performance Management in Football: A Case Study from Chelsea Football Club Academy

Background: Global positioning system (GPS) based player movement tracking data are widely used by professional football (soccer) clubs and academies to provide insight into activity demands during training and competitive matches. However, the use of movement tracking data to inform the design of training programmes is still an open research question. Objectives: The objective of this study is to analyse player tracking data to understand activity level differences between training and match sessions, with respect to different playing positions. Methods: This study analyses the per-session summary of historical movement data collected through GPS tracking to profile high-speed running activity as well as distance covered during training sessions as a whole and competitive matches. We utilise 20,913 data points collected from 53 football players aged between 18 and 23 at an elite football academy across four full seasons (2014–2018). Through ANOVA analysis and probability distribution analysis, we compare the activity demands, measured by the number of high-speed runs, the amount of high-speed distance, and distance covered by players in key playing positions, such as Central Midfielders, Full Backs, and Centre Forwards. Results and Implications: While there are significant positional differences in physical activity demands during competitive matches, the physical activity levels during training sessions do not show positional variations. In matches, the Centre Forwards face the highest demand for High Speed Runs (HSRs), compared to Central Midfielders and Full Backs. However, on average the Central Midfielders tend to cover more distance than Centre Forwards and Full Backs. An increase in high-speed work demand in matches and training over the past four seasons, also shown by a gradual change in the extreme values of high-speed running activity, was also found. This large-scale, longitudinal study makes an important contribution to the literature, providing novel insights from an elite performance environment about the relationship between player activity levels during training and match play, and how these vary by playing position.

Perceptual performance analysis for visual attention model based asymmetric stereoscopic 3D video coding

Asymmetric quality stereoscopic coding has proved to be an effective method in reducing the bandwidth without altering the visual quality. Visual attention cues can also be used in asymmetric coding that has not been widely studied yet. This study reports the performance limits of visual attention aided asymmetric stereoscopic video coding over conventional asymmetric coding.

On the multicast of delay sensitive data in erasure networks using practical network coding

We present a method to estimate the probability of decoding a network coded packet generation transmitted across an erasure network. Simulation results closely correlate to estimated results. The proposed method is used to multicast delay sensitive data at the a.) required delivery probability b.) optimal throughput.

Network coding for error resilient transmission of stereoscopic 3D video

Stereoscopic 3D video is a key enabler of advanced immersive multimedia systems. Network coding on the other hand is a promising technology that would be implemented on the future internet that has the capability to increase the throughput of networks. This paper considers a methodology for 3D video transmission over network coding enabled networks. Specifically, by way of extensive simulations, we compare the error resilient performance of network coding with redundant packets and redundant coding of video streams. Simulation results indicate that in terms of error resilience, packet redundancies at network layer in network coding enabled networks is superior to application level redundancies such as redundant coding of video streams. Thus, this paper illustrates how bandwidth hungry applications such as 3D video distribution could benefit from network coding.