Beyond standard benchmarks: Parameterizing performance evaluation in visual object tracking

Object-to-camera motion produces a variety of apparent motion patterns that significantly affect performance of short-term visual trackers. Despite being crucial for designing robust trackers, their influence is poorly explored in standard benchmarks due to weakly defined, biased and overlapping attribute annotations. In this paper we propose to go beyond pre-recorded benchmarks with post-hoc annotations by presenting an approach that utilizes omnidirectional videos to generate realistic, consistently annotated, short-term tracking scenarios with exactly parameterized motion patterns. We have created an evaluation system, constructed a fully annotated dataset of omnidirectional videos and the generators for typical motion patterns. We provide an in-depth analysis of major tracking paradigms which is complementary to the standard benchmarks and confirms the expressiveness of our evaluation approach

A Programmable Display-Layer Architecture for Virtual-Reality Applications

Two important technical objectives of virtual-reality systems are to provide compelling visuals and effective 3D user interaction. In this respect, modern virtual reality system architectures suffer from a number of short-comings. The reduction of end-to-end latency, crosstalk and judder are especially difficult challenges, each of which negatively affects visual quality or user interaction. In order to provide higher quality visuals, complex scenes consisting of large models are often used. Rendering such a complex scene is a time-consuming process resulting in high end-to-end latency, thereby hampering user interaction. Classic virtual-reality architectures can not adequately address these challenges due to their inherent design principles. In particular, the tight coupling between input devices, the rendering loop and the display system inhibits these systems from addressing all the aforementioned challenges simultaneously. In this thesis, a virtual-reality architecture design is introduced that is based on the addition of a new logical layer: the Programmable Display Layer (PDL). The governing idea is that an extra layer is inserted between the rendering system and the display. In this way, the display can be updated at a fast rate and in a custom manner independent of the other components in the architecture, including the rendering system. To generate intermediate display updates at a fast rate, the PDL performs per-pixel depth-image warping by utilizing the application data. Image warping is the process of computing a new image by transforming individual depth-pixels from a closely matching previous image to their updated locations. The PDL architecture can be used for a range of algorithms and to solve problems that are not easily solved using classic architectures. In particular, techniques to reduce crosstalk, judder and latency are examined using algorithms implemented on top of the PDL. Concerning user interaction techniques, several six-degrees-of-freedom input methods exists, of which optical tracking is a popular option. However, optical tracking methods also introduce several constraints that depend on the camera setup, such as line-of-sight requirements, the volume of the interaction space and the achieved tracking accuracy. These constraints generally cause a decline in the effectiveness of user interaction. To investigate the effectiveness of optical tracking methods, an optical tracker simulation framework has been developed, including a novel optical tracker to test this framework. In this way, different optical tracking algorithms can be simulated and quantitatively evaluated under a wide range of conditions. A common approach in virtual reality is to implement an algorithm and then to evaluate the efficacy of that algorithm by either subjective, qualitative metrics or quantitative user experiments, after which an updated version of the algorithm may be implemented and the cycle repeated. A different approach is followed here. Throughout this thesis, an attempt is made to automatically detect and quantify errors using completely objective and automated quantitative methods and to subsequently attempt to resolve these errors dynamically

A Novel Method for In Vivo Evaluation of Finger Kinematics for Analysis of Activities of Daily Living

This thesis examines the development of a six degrees of freedom finger coordinate system that employs electromagnetic tracking to measure finger kinematics. Secondarily, this thesis validated the in vivo finger coordinate system, and is then used to examine range of motion in the fingers in patients with hand osteoarthritis. Lastly, this thesis examines the range of motion of individuals with and without hand arthritis during various activities of daily living, performed with and with joint protection program principles. This study presents a foundation for finger kinematic evaluation and describes a methodology that will be used for larger studies to be conducted to examine finger kinematics in various clinical and functional applications

Development of an Active Finger Motion Simulator: With In-Vitro Assessments of Tendon Loads and Joint Kinematics

Musculoskeletal injuries of the finger far outnumber those of other joints, and while in-vitro motion simulators are useful for studying joint biomechanics and evaluating surgical repairs, considerably less simulator development has been reported for the finger compared to other joints. Replication of active musculoskeletal movement during in-vitro testing has been shown to be more representative of in-vivo motion patterns, and closed-loop motion controllers are the current state-of-the-art for in-vitro kinematics studies. However, an in-vitro motion simulator with closed-loop tendon load control and simultaneous tendon excursion control has not yet been reported for the finger. This thesis outlines the design and development of an active motion simulator for the study of finger joint kinematics, as well as forces and excursions of the flexor/extensor tendons. Performance of the system was verified in terms of tendon load control accuracy and motion repeatability, before conducting two cadaveric studies. An in-vitro study on the effects of wrist position and distal extensor tendon rupture verified that the new simulator produced expected finger kinematics and tendon loads. With the new simulator validated, its high sensitivity in measuring tendon loads was leveraged to observe the effects of A2 and A4 pulley excision and subsequent surgical repair. The thesis culminates with a summary of sample size analysis and statistical effect sizes that will aid future in-vitro finger studies with this simulator

Development of a low-cost multi-camera star tracker for small satellites

This thesis presents a novel small satellite star tracker that uses an array of low-cost, off the shelf imaging sensors to achieve high accuracy attitude determination performance. The theoretical analysis of improvements in star detectability achieved by stacking images from multiple cameras is presented. An image processing algorithm is developed to combine images from multiple cameras with arbitrary focal lengths, principal point offsets, distortions, and misalignments. The star tracker also implements other algorithms including the region growing algorithm, the intensity weighted centroid algorithm, the geometric voting algorithm for star identification, and the singular value decomposition algorithm for attitude determination. A star tracker software simulator is used to test the algorithms by generating star images with sensor noises, lens defocusing, and lens distortion. A hardware prototype is being assembled for eventual night sky testing to verify simulated performance levels. Star tracker flight hardware is being developed in the Laboratory for Advanced Space Systems at Illinois (LASSI) at the University of Illinois at Urbana Champaign for future CubeSat missions

Metrics for Evaluating Surgical Microscope Usage During Myringotomy

Abstract Although teaching and learning surgical microscope manoeuvring is a fundamental step in middle ear surgical training, currently there is no objective method to teach or assess this skill. This thesis presents an experimental study designed to implement and test sets of metrics capable of numerically evaluating microscope manoeuvrability and qualitatively assessing surgical expertise of a subject during a middle ear surgery called myringotomy. The experiment involved performing a myringotomy on a fixed cadaveric ear. As participants, experienced ear-nose-throat (ENT) surgeons and ENT surgical residents were invited. While performing the procedure, their microscope manoeuvring motions were captured as translational and angular coordinates using an optical tracker. These data were analyzed in terms of motion path length, velocity, acceleration, jitter, manoeuvring volume, smoothness, rotation and time. Participants’ hand motion, body posture and microscopic view were also video recorded to qualitatively assess their surgical expertise. Several metrics were statistically identified as discriminatory. These metrics will be incorporated into a myringotomy surgical simulator to train ENT residents