Use this URL to cite or link to this record in EThOS:
Title: Personal projected displays
Author: Ashdown, M. S. D.
Awarding Body: University of Cambridge
Current Institution: University of Cambridge
Date of Award: 2004
Availability of Full Text:
Full text unavailable from EThOS.
Please contact the current institution’s library for further details.
I present a system called the Escritoire that uses a novel configuration of overlapping projectors to create a large desk display that fills the area of a conventional desk and also has a high resolution region in front of the user for precise work. The projectors need not be positioned exactly—the projected imagery is warped using standard 3D video hardware to compensate for rough projector positioning and oblique projection. Calibration involves computing planar homographies between the 2D co-ordinate spaces of the warped textures, projector framebuffers, desk, and input devices. The video hardware can easily perform the necessary warping and achieves 30 frames per second for the dual-projector display. Oblique projection has proved to be a solution to the problem of occlusion common to front-projection systems. The combination of an electromagnetic digitizer and an ultrasonic pen allows simultaneous input with two hands. The pen for the non-dominant hand is simpler and courser than that for the dominant hand, reflecting the differing roles of the hands in bimanual manipulation. I give a new algorithm for calibrating a pen, that uses piecewise linear interpolation between control points. I also give an algorithm to calibrate a wall display at distance using a device whose position and orientation are tracked in three dimensions. The Escritoire software is divided into a client that exploits the video hardware and han­dles the input devices, and a server that processes events and stores all of the system state. Multiple clients can connect to a single server to support collaboration. Sheets of virtual paper on the Escritoire can be put in piles which can be browsed and reordered. As with physical paper this allows items to be arranged quickly and informally, avoiding the premature work required to add an item to a hierarchical file system. Another interface feature is pen traces, which allow remote users to gesture to each other. I report the results of tests with individuals and with pairs collaborating remotely. Collaborating participants found an audio channel and the shared desk surface much more useful than a video channel showing their faces. The Escritoire is constructed from commodity components, and unlike multi-projector display walls its cost is feasible for an individual user and it fits into a normal office setting. It demonstrates a hardware configuration, calibration algorithm, graphics warping process, set of interface features, and distributed architecture that can make personal projected displays a reality.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available