Engineering Science - Theses, Dissertations, and other Required Graduate Degree Essays

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Hand Tracking and its Pattern Recognition in a Network of Calibrated Cameras

Author: 
Date created: 
2015-04-01
Abstract: 

This thesis presents a vision-based approach for hand gesture recognition which combines both trajectory and hand posture recognition. The hand area is segmented by fixed-range CbCr from cluttered and moving backgrounds, and tracked by Kalman Filter. With the tracking results from two calibrated cameras, the 3D hand motion trajectory can be reconstructed. It is then modeled by dynamic movement primitives (DMP) and a support vector machine (SVM) is trained for trajectory recognition. Scale-invariant feature transform (SIFT) is employed to extract features on segmented hand postures, and a novel strategy for hand posture recognition is proposed. A gesture vector is introduced to recognize hand gesture as a whole which combines the recognition results of motion trajectory and hand postures, where an SVM is trained for gesture recognition based on gesture vectors.

Document type: 
Thesis
File(s): 
Senior supervisor: 
Shahram Payandeh
Department: 
Faculty of Applied Sciences: School of Engineering Science
Thesis type: 
(Thesis) M.A.Sc.

Multiply-and-Forward and Phase-Forward Two Way Relays

Author: 
Date created: 
2015-04-16
Abstract: 

Relay/cooperative communication has been an active area of research in the past few years. In most of the investigations, the amplifiers used in the system are assumed to be linear. In this thesis, we first investigate the effect of amplifier non-linearity has on the bit-error-rate (BER) of a two-way cooperative communication system that employs linear modulation and amplify-and-forward (AF). It was found that irreducible error floor arises, caused by the inter-modulation effect with non-linear amplification and the subsequent imperfect self-interference cancellation. As a result of this finding, we propose two signal forwarding techniques that offer MPSK modulations immunity against non-linear amplifier distortion. The first technique, termed multiply-and-forward (MF), scales the product of the two received signals at the relay for downlink transmission. The second technique, termed phase-forward (PF), has a similar product structure, except that the amplitude information in the product signal is discarded. We show that both schemes do not exhibit the irreducible error characteristic found in AF when the amplifier is non-linear. The PF scheme, in particular, can attain a BER lower than that of AF even when the amplifier is linear. The conclusion is reached that MF and PF are suitable signal forwarding strategies for two-way cooperative communication in the presence of amplifier non-linearity, with PF being the more robust of the two. Due to the multiplicative nature of the MF and PF, self-informantion cancellation becomes simple when differential modulation is used in the two-way cooperative relay system. With differential modulation, there is no explicit channel state information (CSI) estimation and and this leads to a saving of pilot symbol overhead. In the second and third parts of this thesis proposal, we extend the MF and PF protocols to DPSK and CPFSK modulations. Specifically, we demonstrate that the proposed forwarding methods has low computational complexity at the relay as well as simple self-information cancellation at the receiver in the last phase of the cooperative communication. Based on the results we have obtained on the new relay forwarding protocols, we can see that the MF and PF are two promising forwarding techniques and they worth further study and refinement.

Document type: 
Thesis
File(s): 
Senior supervisor: 
Paul Ho
Department: 
Applied Sciences:
Thesis type: 
(Thesis) Ph.D.

Very High Throughput (VHT) Multi-User Multiple Input Multiple Output (MU-MIMO) Communication in 802.11ac

Date created: 
2015-04-28
Abstract: 

Very High Throughput Multi-User Multiple Input Multiple Output (VHT MU-MIMO) is an 802.11ac communication mode that allows an Access Point (AP) to simultaneously transmit multiple data streams as Aggregated Multi-Protocol Data Units (A-MPDUs) to a group of multiple stations (STAs) over the same channel. This mode combines communication technologies that enable the 802.11ac protocol to use spectrum more efficiently compared to the previous standards. However, VHT MU-MIMO wastes an unused part of the Physical Protocol Data Unit (PPDU) interval when short and long data streams are grouped together. In this thesis, we propose a solution that improves VHT MUMIMO communications by reducing wasted portion of the PPDU duration of short data streams by concatenating longer data streams in consecutive groups. Simulations of the VHT MUMIMO communication process with and without the proposed approach indicate smaller wasted part and shorter transmission time of randomly generated STAs data streams.

Document type: 
Graduating extended essay / Research project
File(s): 
Senior supervisor: 
Ljiljana Trajkovic
Department: 
Applied Sciences:
Thesis type: 
(Project) M.Eng.

Flexible Touchpads Based on Inductive Sensors Using Conductive Composite Polymer and Flexible Metal PCB

Author: 
Date created: 
2015-03-11
Abstract: 

In this thesis, the design, fabrication, testing and characterization of two tactile sensor array technologies are presented. The two sensor systems both use inductance as a transduction principle and are designed to be implemented in flexible wearable systems. The tactile sensor arrays feature flexible PCB substrates and/or flexible conductive composite polymer (CCP) structures, resulting in highly flexible tactile arrays. Each switch consists of 4 elements: fascia, target, spacer and a sensor coil. The user presses the fascia, bringing the target in contact with the sensor coil. In the first method, where the system operates based on the principle of eddy current generation, movement of the conductive target changes the inductance of a sensing coil. In the second method, the contact between the target and the conductive membrane triggers a touch detect in the detection mechanism. An electronic circuit that accurately measures inductances is developed to detect the change in the inductance of each sensor’s coil when the user presses the target element of the sensor. Different sizes and geometries of coils in both flexible PCB metal and CCP are investigated to determine which couple best with the CCP that forms the target for the inductive coils. Using COMSOL, a COMSOL simulation of the coil geometries is also conducted in order to study the generated magnetic field and distribution of the magnetic flux density at the center of the coils. Techniques for patterning two-layer inductive coils on flexible PCBs are described. A low cost microfabrication technique to create inductive flexible coils using embedded CCP in polydimethylsiloxane as an alternative to PCB metal coils is also presented. The inductance for a sensor composed of PCB metal coils and CCP target are measured to be approximately 33.1 μH and 42.9 μH for circular and square geometries, respectively, before being pressed. When pressed, a 40% change in the inductance is observed, a change which is easily detected. In the case of coils made of CCP, although the measured inductance values are shifted because of the internal resistance of the coils, a 35% change in the inductance was observed when the conductive target was pressed.

Document type: 
Thesis
File(s): 
Senior supervisor: 
Bonnie Gray
Department: 
Applied Sciences:
Thesis type: 
(Thesis) M.A.Sc.

Designs of application-specific multiview / 3D video coding

Author: 
Date created: 
2014-11-13
Abstract: 

Many applications of multiview or three dimensional (3D) videos have been developed. This poses great challenges to video coding. We study multiview video coding (MVC), perceptual multiview video coding, 3D geometry compression, interactive multiview video streaming (IMVS), and free viewpoint video (FVV). The applications studied in this thesis can be classified into two categories. In the first category we focus on rate-distortion (RD) performance, where the distortion can be measured by mean squared errors (MSE), human visual system based MSE, or metro distance. First, we consider the application of FVV and propose a novel inpainting assisted approach to efficiently compress multiview videos. The decoder can independently recover missing data via inpainting, resulting in lower rate. Second, we study the application of just noticeable distortion (JND)-based MVC and propose to exploit inter-view or temporal redundancy of JND maps to synthesize or predict target JND maps, which are then used to adjust prediction residuals. Third, we study 3D geometry compression and propose a new 3D geometry representation. We project 3D geometry to a collection of surrounding tiles, and subsequently encode these tile images using a modified MVC. The crux of the scheme is the optimal placement of image tiles. In the second category, we study applications where real-time computation and the associated complexity also need to be considered, in addition to the RD performance. These applications include IMVS and FVV. We first consider view switching in IMVS, an application where a network client requests from server a single view at a time but can periodically switch to other views as the video is played back uninterrupted. We propose the optimal frame structure such that frequently chosen view switches are pre-computed while infrequent ones are computed in real-time upon request. On the other hand, we examine the decoder side computational complexity of view synthesis in FVV. We propose to optimally tradeoff transmission rate for decoder-side complexity. For regular view synthesis, we find the optimal subset of intermediate views to code. For a novel inpainting assisted paradigm, we argue that some expensive operations can be avoided by directly sending intra-coded blocks.

Document type: 
Thesis
File(s): 
Senior supervisor: 
Jie Liang
Department: 
Applied Sciences:
Thesis type: 
(Thesis) Ph.D.

Novel Imaging Biomarker Extraction Method for Prognostic Applications in Neuroimaging

Date created: 
2014-10-28
Abstract: 

Biomarkers derived from brain magnetic resonance imaging have promise in being able to assist in the clinical diagnosis of brain pathologies. Imaging biomarkers are a compact representation of knowledge extracted from the medical images. They can be derived from the shape of a particular brain organ, or from the deformation of a region of interest or based on the clinical understanding of a disease. In this thesis, we present novel imaging biomarkers that demonstrate potential for prognostic applications in neuroimaging and dementia. One imaging biomarker is based on the graph-theoretic analysis of inter-regional co-variation in cortical thickness, while the other is based on the Laplacian Eigen decomposition of the segmentation of a brain organ. We test these features on three distinct, but related, classification problems i.e. early detection of Alzheimer disease (AD), differential diagnosis of AD and Frontotemporal disease, and earlier detection of AD via the sub-classification of multiple domain amnestic mild cognitive impairment (MCI). We also present a novel cross- validation method that can handle class imbalance, and present comprehensive analysis into their classification performance.

Document type: 
Thesis
File(s): 
Senior supervisor: 
Mirza Faisal Beg
Department: 
Applied Sciences:
Thesis type: 
(Thesis) Ph.D.

Visual attention retargeting

Date created: 
2014-12-08
Abstract: 

This thesis explores attention retargeting---a concept related to visual saliency where the content or composition of an image is altered in an effort to guide the viewer's attention. Attention retargeting is currently in its infancy with numerous unexplored possibilities, no common methodology for evaluating performance, and no unified framework. The difficulty of attention retargeting as a saliency inversion problem lies in the lack of one-to-one mapping between saliency and the image domain, in addition to the possible negative impact of saliency alterations on image naturalness. Several approaches from recent literature to solve this challenging problem are reviewed in this context. Two novel attention retargeting methods are proposed to efficiently compute a region's propensity for drawing attention after it has been modified. The first method manipulates the orientation of a selected region, while the second modifies its hue. Both methods are applied to maximize the saliency of selected regions in various images. The likelihood of drawing attention towards the modified regions is evaluated through eye-tracking. Subjective experiments, in which participants are told to decide which image looks better between two alternatives, are used to measure the relative naturalness of the modification. An experiment was conducted to determine whether subliminal flicker is capable of drawing attention in natural images without the viewer's knowledge. Flicker was introduced to selected regions in a set of images by alternating the contrast in these regions from high to low at a frequency of 50 Hz. A comparison of eye-tracking data between participants who viewed the flickering images against those who viewed the original images suggests that subliminal flicker may, on average, repel attention rather than attract it.

Document type: 
Thesis
File(s): 
Senior supervisor: 
Ivan V. Bajic
Department: 
Applied Sciences:
Thesis type: 
(Thesis) M.A.Sc.

Ophthalmic Imaging Applications with Optical Coherence Tomography and Graphics Processing Units

Peer reviewed: 
No, item is not peer reviewed.
Date created: 
2014-12-05
Abstract: 

In ophthalmology, Optical Coherence Tomography (OCT) is becoming one of the dominant imaging technologies for both clinical diagnostics and vision research. In a previous bachelor’s thesis prior to this project, we described a highly optimized Graphics Processing Unit (GPU) implementation of the Fourier Domain (FD)OCT processing and visualization pipeline that was capable of real-time volume rendering at video rate.In this thesis, we describe three applications that build upon the GPU-based processing software: Speckle Variance (sv)OCT, Compressive Sample (CS)OCT, and Wavefront Sensorless Adaptive Optics (WSAO)OCT. We first demonstrate that svOCT can be a powerful fundus imaging technique for visualizing the retinal vasculature network, which may be comparable to the gold-standard technique called Fluorescein Angiography (FA). The strongest attribute of svOCT is that it bypasses the use of intravenous fluorescein for vascular contrast enhancement, and can be highly suitable for longitudinal monitoring of patients with vasculature-related pathologies in the retina. In our second application, we present a GPU-accelerated CS-OCT processing pipeline. The principle behind CS-OCT is to take advantage of the redundancy in biological structures, such as the retina, for reconstructing volumes acquired at a sampling density below the Nyquist criterion; the purpose is to justify decreasing volume acquisition time by significantly subsampling the datasets. In our final application, we present a WSAO-OCT system as a novel technique for cellular resolution imaging of the human photoreceptor layer. This technique leverages on the ultrahigh speed processing rates in our GPU-based processing software in order to produce a real-time intensity-based merit function for en face image quality optimization.

Document type: 
Thesis
File(s): 
Senior supervisor: 
Marinko V. Sarunic
Department: 
Applied Sciences:
Thesis type: 
(Thesis) M.A.Sc.

Asymmetric Coherent Configurable Caches for PolyBlaze Multicore Processor

Author: 
Date created: 
2014-11-28
Abstract: 

Modern computing systems gain performance by several means such as increased parallelism through using Chip-level Multiprocessor (CMP) systems. Symmetric Multiprocessor (SMP) systems use uniform processing cores to form a CMP in which all cores are identical in every aspect. Conversely, Asymmetric Multiprocessor (AMP) systems consist of processing cores with variable configurations such as different cache configurations, co-processors, and cache sizes. AMP systems coupled with such smart scheduling algorithms can improve resource utilization while maintaining overall system performance because real-time profiling in a computing system using light-weight hardware profilers can help smart scheduling algorithms make meaningful decisions. In other words, the vision into an application’s behavior helps in the decision making process on how to allocate available resources for different applications without penalizing the performance by putting too much overhead on the system. Currently, there is no AMP research framework available that allows us to look into asymmetry in processing systems. In this thesis, we present an extension on PolyBlaze framework for asymmetric coherent Level-1 (L1) caches. Our implementation in this work includes other arbiter and prefetching units as well. We measure data cache read miss rates and application run-times for select benchmarks from SPEC CPU2006 executed in a Linux environment on top of a variety of cache configurations. In the scope of this work, we manually assign applications to cores to take advantage of AMP configurations. Our results show that in a AMP system, different applications can benefit from various configurations to complete their work faster using less resources.

Document type: 
Thesis
File(s): 
Senior supervisor: 
Lesley Shannon
Alexandra Fedorova
Department: 
Applied Sciences:
Thesis type: 
(Thesis) M.A.Sc.

Real-time retinal blood flow imaging with Fourier Domain Optical Coherence Tomography

Author: 
Date created: 
2014-12-01
Abstract: 

Optical Coherence Tomography (OCT) is a non-invasive micrometer-resolution depth resolved medical imaging tool for diagnostic visualization of the retinal structures in vivo. In this thesis, we first describe the capability of OCT for providing structural information by quantitative retinal thickness measurements in animal models of diseases causing vision loss. In the rest of the work described in this thesis, we focus on the development of an extension of OCT called speckle variance (sv) OCT, which provides functional information such as detecting capillaries within in the retina. Retinal capillary networks are critically linked to retinal neuronal health and disease. The ability to perform accurate in vivo examination of human retinal capillary networks is therefore valuable for studying mechanisms that govern retinal homeostasis and retinal vascular diseases. A real-time implementation of the svOCT provided by the GPU acceleration was described to provide visualization of en-face vasculature networks during acquisition. A qualitative comparison study was described in this thesis by comparing the retinal vasculature images acquired from svOCT and Florescence Angiography (FA) for both healthy and diseased patients. The capability of svOCT with respect to quantifying capillary network information has been also validated in this thesis. The results of these studies suggest that this GPU accelerated svOCT has the potential to non-invasively provide useful quantitative information about human retinal capillary networks, and may have clinical and research applications for the management of retinal microvascular diseases, a major cause of vision loss worldwide. To further adapt the svOCT to be more clinical friendly, preliminary work on enhancing the real-time visualization of vascular information from distinct retinal capillary beds during acquisition was proposed and implemented in this thesis.

Document type: 
Thesis
File(s): 
Senior supervisor: 
Marinko V. Sarunic
Department: 
Applied Sciences:
Thesis type: 
(Thesis) Ph.D.