Eva Cheng

An Iterated Extended Kalman Filter for 3D mapping via Kinect camera

This paper proposes the use of the Iterated Extended Kalman Filter (IEKF) in a real-time 3D mapping framework applied to Microsoft Kinect RGB-D data. Standard EKF techniques typically used for 3D mapping are susceptible to errors introduced during the state prediction linearization and measurement prediction. When models are highly nonlinear due to measurement errors e.g., outliers, occlusions and feature initialization errors, the errors propagate and directly result in divergence and estimation inconsistencies. To prevent linearized error propagation, this paper proposes repetitive linearization of the nonlinear measurement model to provide a running estimate of camera motion. The effects of iterated-EKF are experimentally simulated with synthetic map and landmark data on a range and bearing camera model. It was shown that the IEKF measurement update outperforms the EKF update when the state causes nonlinearities in the measurement function. In the real indoor environment 3D mapping experiment, more robust convergence behavior for the IEKF was demonstrated, whilst the EKF updates failed to converge.

Multimedia adaptation based on semantics from social network users interacting with media

A key goal of adaptive multimedia delivery is to provide users with content that maximizes their quality of experience. To achieve this goal, adaptive multimedia systems require descriptions of the content and user preference information, moving beyond traditional criteria such as quality of service requirements or perceptual quality based on traditional metrics. Media is increasingly consumed within online social networks and multimedia sharing websites can also add a wealth of metadata. In this paper, mechanisms for gathering semantics that relate to user preferences when interacting with media content in social networks are proposed. Subjective results indicate the proposed mechanisms can successfully provide information about user and social group media preferences that can be used for adapting multimedia for improved user quality of experience.

Review on using physiology in quality of experience.

In the area of Quality of Experience (QoE), one challenge is to design test methodologies in order to evaluate the perceived quality of multimedia content delivered through technical systems. Traditionally, this evaluation is done using subjective opinion tests. However, sometimes it is difficult for observers to communicate the experienced quality through the given scale. Furthermore, those tests do not give insights into how the user is reacting on an internal physiological level. To overcome these issues, one approach is to use physiological measures, in order to derive a direct non-verbal response of the recipient. In this paper, we review studies that have been performed in the domain of QoE using physiological measures and we look into current activities in standardization bodies. We present challenges this research faces. and give an overview on what researchers should be aware of when they want to start working in this research area.

Eight solutions of the essential matrix for continuous camera motion tracking in video augmented reality

This paper considers a self-calibration approach to the estimation of motion parameters for an unknown camera used for video-based augmented reality. Whilst existing systems derive four SVD solutions of the essential matrix, which encodes the epipolar geometry between two camera views, this paper presents eight possible solutions derived from mathematical computation and geometrical analysis. The eight solutions not only reflect the position and orientation of the camera in static displacement but also the dynamic, relative orientation between the camera and an object in continuous motion. This paper details a novel algorithm that introduces three geometric constraints to determine the rotation and translation matrix from the eight possible essential matrix solutions. An OpenGL camera motion simulator is used to demonstrate and evaluate the reliability of the proposed algorithms; this directly visualizes the abstract computer vision parameters into real 3D.

Geometrical room geometry estimation from room impulse responses

Room geometry estimation from corresponding Room Impulse Responses (RIRs) has attracted much attention in recent years, and a key challenge is to find the first order image source locations from the RIRs under different environments. Unlike the existing approaches which require a priori knowledge of the room or require some ideal conditions, this paper proposes an intuitive geometrical method based on the acoustical image source model. The proposed approach does not need any a priori knowledge of the room, only the RIRs from one arbitrary source location to five arbitrary receiving locations. The first order image sources of the walls in a room are identified first, then the room geometry is estimated based on the wall locations using a geometrical approach. Simulations with 2D and 3D convex polyhedral rooms demonstrate the feasibility and the precision of the proposed approach is discussed.

3D fatigue from stereoscopic 3D video displays: Comparing objective and subjective tests using electroencephalography

The use of stereoscopic display has increased in recent times, with a growing range of applications using 3D videos for visual entertainment, data visualization, and medical applications. However, stereoscopic 3D video can lead to adverse reactions amongst some viewers, including visual fatigue, headache and nausea; such reactions can further lead to Visually Induced Motion Sickness (VIMS). Whilst motion sickness symptoms can occur from other types of visual displays, this paper investigates the rapid adjustment triggered by human pupils as a potential cause of 3D fatigue due to VIMS from stereoscopic 3D displays. Using Electroencephalogram (EEG) biosignals and eye blink tools to measure the 3D fatigue, a series of objective and subjective experiments were conducted to investigate the effect of stereoscopic 3D across a series of video sequences.

On the effect of amr and AMR-WB GSM compression on overlapped speech for forensic analysis

The recent ubiquity of mobile telephony has posed the challenge of forensic speech analysis on compressed speech content. Whilst existing research studies have investigated the effect of mobile speech compression on speaker and speech parameters, this paper addresses the effect of speech compression on parameters when an interfering background speaker is present in clean and noisy conditions. Preliminary evaluations presented in this paper study the effect of the Adaptive Multi-Rate (AMR) and Adaptive Multi-Rate Wideband (AMR-WB) speech coders on the Linear Prediction (LP) speech spectrum, Line Spectral Frequencies (LSFs), and Mel Frequency Cepstral Coefficients (MFCCs). Results indicate that due caution should be employed for the forensic analysis of mobile telephony speech: speech coder parameters are significantly degraded when an interfering speaker or noise is present, compared to parameters obtained from the main speaker alone. Moreover, at high SNR the speech parameters exhibit values that gradually transition from those ideally and independently obtained from the main speaker to those of the background speaker as the amplitude of the background interfering speaker increases.

The role of experts in social media — Are the tertiary educated engaged?

With new social media technologies arising daily, this paper reports on a pilot user survey that studies how tertiary educated users are engaging with social media. The results indicate sporadic use of social media by the tertiary educated users studied; they are generally aware of the key social media sites and facilities, but are not actively utilizing these services. The reasons for, and the implications of a lack of tertiary educated users in the egalitarian and participatory environments intrinsic to social media are discussed. Further, the paper suggests potential technological barriers that might be at the root of such a lack of engagement amongst tertiary educated users.

Automatic multiple zebrafish larvae tracking in unconstrained microscopic video conditions

The accurate tracking of zebrafish larvae movement is fundamental to research in many biomedical, pharmaceutical, and behavioral science applications. However, the locomotive characteristics of zebrafish larvae are significantly different from adult zebrafish, where existing adult zebrafish tracking systems cannot reliably track zebrafish larvae. Further, the far smaller size differentiation between larvae and the container render the detection of water impurities inevitable, which further affects the tracking of zebrafish larvae or require very strict video imaging conditions that typically result in unreliable tracking results for realistic experimental conditions. This paper investigates the adaptation of advanced computer vision segmentation techniques and multiple object tracking algorithms to develop an accurate, efficient and reliable multiple zebrafish larvae tracking system. The proposed system has been tested on a set of single and multiple adult and larvae zebrafish videos in a wide variety of (complex) video conditions, including shadowing, labels, water bubbles and background artifacts. Compared with existing state-of-the-art and commercial multiple organism tracking systems, the proposed system improves the tracking accuracy by up to 31.57% in unconstrained video imaging conditions. To facilitate the evaluation on zebrafish segmentation and tracking research, a dataset with annotated ground truth is also presented. The software is also publicly accessible.

Pressure spectra in turbulent flows in the inertial and the dissipation ranges

Based on existing studies that provide the pressure spectra in turbulent flows from the asymptotic pressure structure function in the inertial range, this paper extends the pressure spectrum to the dissipation range by proposing a pressure structure function model that incorporates both the inertial and dissipation ranges. Existing experiment results were used to validate the proposed pressure structure function model first, and then the obtained pressure spectrum was compared with the simulation and measurement data in the literature and the wind-induced noise measured outdoors. All comparisons demonstrate that the pressure spectrum obtained from the proposed pressure structure function model can be used to estimate the pressure spectra in both the inertial and dissipation ranges in turbulent flows with a sufficiently large Reynolds number.