Department Publications

In this thesis, multidimensional signal processing techniques to mitigate disturbances in synthetic aperture systems such as radio telescopes are investigated. Here, two computationally efficient three-dimensional (3D) spatio-temporal (ST) finite impulse response (FIR) cone filter bank structures are proposed. Furthermore, a strategy is proposed to design 3D ST FIR frustum filter banks, having double-frustum-shaped passbands oriented along the temporal axis, derived from appropriate 3D ST FIR cone filter banks. Both types of cone and frustum filter banks are almost alias free and provide near-perfect reconstruction. In the proposed cone and frustum filter banks, both temporal and spatial filtering operations can be carried out at a significantly lower rate compared to previously reported 3D ST FIR cone filter banks implying lower power consumption. Furthermore, the proposed cone and frustum filter banks require a significantly lower computational complexity than previously reported 3D ST FIR cone and frustum filter banks. Importantly, this is achieved without deteriorating the improvement in signal-to-interference-plus-noise ratio. A theoretical analysis of brightness distribution (BD) errors caused by parameter perturbations and mismatches among the transfer functions of receivers employed in synthetic aperture systems is presented. First, the BD errors caused by perturbations in the transfer functions of low noise amplifiers (LNAs) and anti-aliasing filters (AAFs) are considered, and the characteristics of the additive BD error and its effects on synthesized BDs are thoroughly analyzed. Second, the conditions that should be satisfied by the transfer …

Motion Blur due to the relative motion between the camera and object can seriously degrade image quality. We present an FPGA based motion blur detection and correction algorithm which is implemented on top of a configurable soft-processor based architecture. The system consists of two main modules. The blur detection module identifies the blur length and angle, and the restoration module uses regularized inverse filtering to remove the motion blur. The Processing algorithms are implemented as separate cores on the FPGA fabric where the soft processor core is only used for managing system configuration. The system can achieve a frame rate of 15fps for a 720p HD video stream.

Lankan agricultural community. The objective of this paper is to identify the methods and implementations that can be applied to the agricultural sector of Sri Lanka. While composing the framework with identified implementations the cost, scientific and technological knowledge of the farmers were taken into consideration.

It is known that every working day millions of drivers are looking for a place to park and most of the urban traffic occur due to the drivers loitering in search of parking spaces. We wished to offer a simple solution to this problem by implementing a car park navigating system using ultrasonic sensors. RS-485 protocol, a mobile application and Bluetooth communication. The system indicates whether the car park is full or not and provide a simple navigation to the driver to the vacant spot.

Real Time Location Estimation systems (RTLS) developed for outdoor environments have shown significant errors due to changes in atmospheric conditions, multipath propagation and inherent signal strength variations. In this paper, we present an improved Wi-Fi based RTLS solution for the outdoors that reduces the above impacts. In addition this paper presents the development of a portable device for implementing the above RTLS solution. The research makes use of Euclidean, standard deviation based and probabilistic algorithms. Data smoothening is done to reduce the multipath propagation issues. The different algorithm combinations are compared via their error cumulative distribution functions.

The paper presents a video transmission technique for surveillance systems deployed over wireless networks. In order to be integrated into modern wireless and IP based networks, video surveillance systems should possess the ability to deal with variable network quality. The developed technique allows the system to adaptively compensate for unpredictable changes in the network. A statistical method is used to predict parameters related to network quality, and accordingly vary the frame rate of the video stream transmitted.

In this work we focus on the problem of detecting vehicles that come to a stop, in a video of approximately 15 frames per second. The videos are retrieved by surveillance cameras fixed as shown in Fig. 1 which are located few meters from the ground.

Increasing use of CCTV for city and building surveillance has given rise to an environment where an object (a person) might traverse through the field of vi>vv of many cameras. In this paper we explore the problem of tracking multiple objects in a multi camera environment, which is a highly addressed area in computer vision. Our research involves real time tracking of objects while they are moving in a multi camera environment with non-overlapping field of v/ewjr and detecting them when they re-uppear in the same or another camera in the same system. Previous methods of using offline trained classifiers with huge databases are time consuming and have the drawback of incapability of detecting arbitrarily selected objects. We address this issue by online training with the initial sample given and is based on the TLD (Tracking, Learning, Detection) framework. We extend the idea to formulate our methodology to …

In computer vision crass-correlation is a standard approach for local feature matching in feature tracking applications. For this Normalized cross-correlation (NCC) is implemented on spatial domain, because it does not have a simple and efficient frequency domain expression. Therefore in applications which demand real-time processing, a dedicated hardware implementation of NCC is essential to meet the computational cost in spatial domain. In this paper we present a Field Programmable Gate Array (FPGA) implementation of NCC based on the multi-port memory controller together with Fast Normalize Cross-correlation. Practical experimentation shows that our system can achieve frame rates closer to 100 for a search window size of 100x100 and template size of 15x15, with only using two dual-port memories.

The growth of the Sri Lankan healthcare sector is a necessity at this stage due to an increasingly ageing community and a significant increase in non-communicable diseases. Despite many regulations that given the sector, it continues to be inundated with many problems in relation to delivery of healthcare services./ Although the state is a prominent player in the industry, private sector healthcare facilities provide curative out patitent care to 60% of the population in the country. The World Health Organisation strategic agenda, Strategic Framework for Health Development in Sri Lanka as well as the Health Master Plan had highlighted the necessity of Information Systems for improved service delivery in the sector./ The existing Information Systems with it's administrative and financial bias has failed to add value in the interaction between the healthcare worker and the patient. The study investigates the possible …

Augmented Reality (AR) is one of the emerging technologies being used for enhancing user experience in many applications. Specific devices for various tasks are been replaced by Smart Phones making them a unique platform to implement all functionalities in one device. In this paper we present a real-time AR framework for mobile devices that takes into consideration key technical challenges such as limited processing power and battery life. The framework is having four separate modules, Marker Detection, Identification, Camera pose calculation and Embedding visual information. A 2D pattern called a marker is used to uniquely identify the objects. The marker in the camera view is detected and tracked so that information contained in the marker is exploited. Tracked four corners of the marker are used to calculate the 6 DOF of camera position, which is further processed to place 3D graphics on the real scene …

第 22 回アストロダイナミクスシンポジウム (2012 年 7 月 30-31 日. 宇宙航空研究開発機構宇宙科学研究所 (JAXA)(ISAS)), 相模原市, 神奈川県

Chess is one of the world’s most widespread games. We propose the novel concept of ‘group chess’, with the objective of using information technology as an educational aid for novice chess players, as well as for experienced players to play as groups. In the proposed game, up to thirty players can play chess in two groups. The player who makes the best move at each turn is awarded with marks. Finally the player with the highest marks wins. Artificial intelligence and networking technologies are used in the system. The Alpha Beta pruning algorithm is used to find the best movement out of a set of given inputs. This is a new adaptation of the Alpha Beta pruning which is normally used to find the best possible move. We propose this game for chess learners as well as a novel approach to the game for experienced players. The concept of 'group chess' will direct future development of the game of chess towards a new …

Novel single-integral representations for the multivariate probability density functions and cumulative distribution functions of Gaussian class distributions (Rayleigh, Rician, Weibull, Nakagami- m , and generalized Rician) are derived. The solutions are expressed in terms of well-known functions which are available in common mathematical software. The marginal random variables are not necessarily identically distributed as is the case for some past solutions. A generalized correlation structure based on a special linear transformation of independent Gaussian random variables is used in this study. The advantage of the new representation is that only a single-integral computation is needed to compute an N -dimensional distribution.

This paper suggests a decision support system for vehicle drivers, accessible via mobile phone. Concept behind the system is to help drivers to schedule their activities, best utilizing their time along the way, minimizing the impacts of traffic. This is in contrast to existing approaches focused on controlling traffic in highways. Vehicle is continuously tracked along the journey and information presented to user is adapted according his location and time dimensions. System is based on a decision tree based classification model to predict the future traffic and use those results for decision making. System mines spatio-temporal data to build the decision tree, therefore developed in a distributed architecture to avoid load for a single server. System is exposed to community via existing social networks, bringing social networks into vehicular context. Decision trees to predict traffic are periodically rebuilt using most recent data …

A novel approach is introduced for the analysis of energy detection of unknown deterministic signals, where the energy detector uses dual diversity reception. The energy detector is assumed to employ a low complexity diversity technique, namely square-law combining. A general case where the two diversity branches are correlated is treated by the analysis. Detection and false alarm probabilities for the energy detector are derived for correlated Rayleigh and Rician fading channels.

Online learning is commonly accepted as a support tool for educators as well as a medium of delivery of any-time, any-where content of a wide range of study programs to a widely dispersed learner community. Web-based learning environments are a relatively new medium of learning to Sri Lankan universities. Characteristics of learners of such environments vary widely, from technology geniuses to technological novices, from high bandwidth access to slow Internet connections etc. There are predictions of a near future boom of digital learning in Asian educational context, challenging the conventional face to face learning environments. Like any learning process, digital learning depends on effective communication of human knowledge, whether this occurs in a face-to-face classroom or across the Internet. The effectiveness of digital learning also depends on establishing two-way communication between facilitators and learners, and among learners themselves. Within the state university settings, learners experience varied emotions and interest towards learning. Although both emotions and interest can increase learners’ likelihood to engage in traditional learning, little is known about the influence of emotions and interest in learning activities in a digital environment. Previous research have identified that emotions occur while individuals assess events in their environment that are related to the needs, goals and well-being. Moreover, recent research on the emotional response to online learning has focused on the importance of learners’ feelings in relation to the community of learning. Major objective of this research study is to introduce a …

Novel single-integral representations for the bivariate probability density function and cumulative distribution function of two correlated Rician random variables are derived. The solutions are expressed in terms of well known functions which are available in common mathematical software. The two random variables are not necessarily identically distributed as required by some past solutions. The new form of the bivariate Rician cumulative distribution function is applied to give a new expression for the outage probability of dual selection combining diversity operating in correlated Rician fading.

We present the design and implementation of intrusion detection and alerting mechanism (eleAlert) for fences separating wildlife habitats and human settlements. Our objective is to improve the effectiveness of electric fences as a solution to the prevailing human-elephant conflict (HEC) in many parts of the world. eleAlert uses a network of sensors to detect and locate damages instantly and alert communities under threat via the mobile communications network.

Novel representations for the multivariate probability density function and cumulative distribution function of the non-central chi-square distribution are derived. The solutions are expressed in terms of well known functions which are available in common mathematical software. When the number of degrees of freedom, m, is even, the new representation has the advantage that only a single-integral computation is needed to compute a N-dimensional distribution. The new representations are used to numerically evaluate the outage probability of multiple input multiple output systems with receiver antenna selection, operating in correlated Rician fading. The well known equal correlation model, which is considered to be a useful model for a closely placed set of antennas, is used for the analysis.

Optimum capacity scaling in the downlink of a single-cell multiple-input multiple-output communication system can be achieved by a communication strategy called opportunistic beamforming in which information carrying beams are randomly formed and users are opportunistically scheduled based on their partial channel state information. Even though opportunistic beamforming reduces the amount of feedback required to achieve optimum capacity scaling laws, the number of users feeding back in its plain implementations still grows linearly with the total number of users in the system, which is an onerous requirement on the feedback channel. In this paper, we focus on a more stringent but realistic O(1) feedback constraint on the feedback channel, and obtain the tradeoff curve tracing the Pareto optimal boundary between feasible and infeasible feedback-rate pairs. We show that any point on this tradeoff curve …

Traditional monoSLAM assumes stationary landmarks making it unable to cope up with dynamic environments where moving objects are present in the scene. This paper presents the parallel implementation of monoSLAM with a set of independent EKF trackers where stationary features and moving features are tracked separately. The difficult problem of detecting moving points from a moving camera is addressed by the epipolar constraint computed by using the measurement information already available with the monoSLAM algorithm. While doing so SLAM measurement outlier rejection is also performed. Results are presented to verify and highlight the advantages of our approach over traditional SLAM.

It is shown that, by employing 2D FIR spatial filters and under-decimation, the computational time of 3D space-time polyphase cone filter banks may be significantly reduced. The resultant input-output 3D transfer function is almost alias-free and, further it is shown that the proposed cone filters can be used to effectively attenuate such stopband signals as radio frequency interference in radio astronomy applications.