VOLUMETRIC AND VARIFOCAL-OCCLUSION AUGMENTED REALITY DISPLAYS

Augmented Reality displays are a next-generation computing platform that offer unprecedented user experience by seamlessly combining physical and digital content, and could revolutionize the way we communicate, visualize, and interact with digital information. However, providing a seamless and perceptually realistic experience requires displays capable of presenting photorealistic imagery, and especially, perceptually realistic depth cues, resulting in virtual imagery being presented at any depth and of any opacity. Today's commercial augmented reality displays are far from perceptually realistic because they do not support important depth cues such as mutual occlusion and accommodation, resulting in a transparent image overlaid onto the real-world at a fixed depth. Previous research prototypes fall short by presenting occlusion only for a fixed depth, and by presenting accommodation and defocus-blur only for a narrow depth-range, or with poor depth or spatial resolution. To address these challenges, this thesis explores a computational display approach, where the display’s optics, electronics, and algorithms are co-designed to improve performance or enable new capabilities. In one design, a Volumetric Near-eye Augmented Reality Display was developed to simultaneously present many virtual objects at different depths across a large depth range (15 - 400 cm) without sacrificing spatial resolution, frame rate, or bitdepth. This was accomplished by (1) synchronizing a high-speed Digital Micromirror Device (DMD) projector and a focus-tunable lens to periodically sweep out a volume composed of 280 single-color binary images in front of the user's eye, (2) a new voxel-oriented decomposition algorithm, and (3) per-depth-plane illumination control. In a separate design, for the first time, we demonstrate depth-correct occlusion in optical see-through augmented reality displays. This was accomplished by an optical system composed of two fixed-focus lenses and two focus-tunable lenses to dynamically move the occlusion and virtual image planes in depth, and designing the optics to ensure unit magnification of the see-through real world irrespective of the occlusion or virtual image plane distance. Contributions of this thesis include new optical designs, new rendering algorithms, and prototype displays that demonstrate accommodation, defocus blur, and occlusion depth cues over an extended depth-range.Doctor of Philosoph

Recursive meta-clustering in a granular network

Granular computing represents an object as an information granule. Traditionally the information is derived from the primary source of data by recording events such as transactions, phone calls, user sessions, security breaches, and car trips. Much of the early data mining techniques used information granules generated from primary data sources. Recent data mining techniques such as ensemble classifiers and stacked regression use secondary sources of data obtained from initial data mining activities. Typically, these techniques use preliminary applications of data mining techniques for initial knowledge discovery. The knowledge acquired from the preliminary data mining is then used for more refined analysis. Granular computing can enable us to develop a formal framework for incorporating information from both primary and secondary sources of data. This enhanced granular representation can help us develop integrated data mining techniques. This paper proposes a novel recursive meta-clustering algorithm to demonstrate the versatility of granular computing for developing integrated data mining techniques to exploit primary and secondary knowledge sources.by Pawan Lingras and Kishore Rathinave

Towards a switchable AR/VR near-eye display with accommodation-vergence and eyeglass prescription support

In this paper, we present our novel design for switchable AR/VR near-eye displays which can help solve the vergence-accommodation-conflict issue. The principal idea is to time-multiplex virtual imagery and real-world imagery and use a tunable lens to adjust focus for the virtual display and the see-through scene separately. With this novel design, prescription eyeglasses for near- and far-sighted users become unnecessary. This is achieved by integrating the wearer's corrective optical prescription into the tunable lens for both virtual display and see-through environment. We built a prototype based on the design, comprised of micro-display, optical systems, a tunable lens, and active shutters. The experimental results confirm that the proposed near-eye display design can switch between AR and VR and can provide correct accommodation for both.NRF (Natl Research Foundation, S’pore)Accepted versio