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A system for visual guidance in patient set-up for external-beam radiotherapy procedures was developed using augmented reality. The system uses video cameras to obtain views of the linear accelerator, and the live images are displayed on a monitor in the treatment room. A 3D model of the patient's external surface, obtained from planning CT data, is superimposed onto the treatment couch in the camera images. The augmented monitor can then be viewed, and alignment performed against the virtual contour. The system provides an intuitive method for set-up guidance, and allows non-rigid deformations to patient pose to be visualised. It also allows changes to patient geometry between treatment fractions to become observable, and can remain in operation throughout the treatment procedure, so that patient motion becomes apparent. Coordinate registration between the camera view and the linac is performed using a cube which is aligned with the linac isocentre using room lasers or cone-beam CT. The AR tracking software detects planar fiducial tracking markers attached to the cube faces, and determines their positions in order to perform pose estimation of the 3D model on-screen. Experimental results with an anthropomorphic phantom in a clinical environment have shown that the system can be used to position a rigid-body with a translational error of 3 mm, and a rotational error of 0.19 degrees, 0.06 degrees and 0.27 degrees, corresponding to pitch, roll and yaw respectively. With further developments to optimise the system accuracy and its interface, it could be made into a valuable tool for radiotherapy clinics. The outcome of the project has been encouraging, and has shown that augmented reality for patient set-up guidance has great potential.

With augmented reality, we can create interfaces that merge virtual objects and data seamlessly with the real world, potentially improving collaboration and interaction. This technology offers opportunities for games, allowing new designs that merge the diverse social and physical interaction of real world games with rapid interactivity and computing power of digital games. To date, research has primarily focused on issues of technology, interaction design, and nfrastructure; the design of compelling play has received little attention. We play games because they are enjoyable; therefore, in order to create attractive games, we must understand enjoyment. In games, engagement, social interaction, and emotional involvement are among the most common causes. We can design for engagement in play using Csikszentmihalyi's model of 'flow'; for social play by making communication easy, natural, and useful; and emotional involvement by understanding the mechanisms by which games stimulate us. Alongside an understanding of enjoyment, lessons must be drawn from design experience. AR Tankwar is an augmented reality strategy game developed over the course of this thesis, and has been evaluated in the field at a large games convention, and in a detailed comparative study with existing games on tabletop and desktop PC. Evaluations revealed predictable limitations with the technology, but also provided insight into how designers can make best use of the medium. Based on these activities, and existing knowledge of interaction and collaboration in augmented reality, this thesis addresses compelling play in augmented reality by developing a set of design guidelines for augmented reality games, with particular focus on strategy games.

In recent years, technical advances in the field of Augmented Reality (AR), coupled with the acceleration in computer and graphics processing power, have brought robust and affordable AR within the reach of the wider research community. While the technical issues of AR remain heavily researched, there is also a growing amount of work on user interface development and evaluation, heralding the convergence of traditional Human Computer Interaction (HCI) and AR. Magic Lenses are 2D interface components that provide alternative representations of objects seen through them. In this way, they can be used to provide Focus and Context in the interface, especially when visualising layered information. There are very few, if any, formal evaluations to guide the development of lens-based interfaces. This thesis describes the development and evaluation of Magic Lenses as a tool for AR interfaces. The work starts with a comprehensive survey of many Focus and Context techniques, which are classified based on the way they present views to the users { for example, a Magic Lens is a spatially separated multiple view technique. A formal evaluation of 2D Magic Lenses in a GIS scenario found that users strongly preferred the lens-based interaction technique to others, largely because it reduced the effort of interaction. Accuracy was high with the lenses, but a simple "global view" interface allowed significantly faster performance. This positive result motivated further work on Magic Lenses within AR, where the lens metaphor can reinforce the tangible interaction methods that link virtual and real content. To support rapid exploration of interaction alternatives with AR Magic Lenses, I describe the design and architecture of osgART, an AR development toolkit that is available to the research community as open-source software. Object selection and manipulation is a fundamental interaction requirement for all AR interfaces, and I establish an empirical foundation of performance in this task with a variety of AR interaction techniques, including Magic Lenses. Results show that performance with all techniques is successfully modelled by Fitt's Law, and that Magic Lenses outperformed other techniques. Finally, I examine new interaction techniques based on Magic Lenses, particularly a Flexible Sheet Lens, which allows concurrent bimanual specification of multiple parameters within the visualisation.

A system for visual guidance in patient set-up for external-beam radiotherapy procedures was developed using augmented reality. The system uses video cameras to obtain views of the linear accelerator, and the live images are displayed on a monitor in the treatment room. A 3D model of the patient's external surface, obtained from planning CT data, is superimposed onto the treatment couch in the camera images. The augmented monitor can then be viewed, and alignment performed against the virtual contour. The system provides an intuitive method for set-up guidance, and allows non-rigid deformations to patient pose to be visualised. It also allows changes to patient geometry between treatment fractions to become observable, and can remain in operation throughout the treatment procedure, so that patient motion becomes apparent. Coordinate registration between the camera view and the linac is performed using a cube which is aligned with the linac isocentre using room lasers or cone-beam CT. The AR tracking software detects planar fiducial tracking markers attached to the cube faces, and determines their positions in order to perform pose estimation of the 3D model on-screen. Experimental results with an anthropomorphic phantom in a clinical environment have shown that the system can be used to position a rigid-body with a translational error of 3 mm, and a rotational error of 0.19 degrees, 0.06 degrees and 0.27 degrees, corresponding to pitch, roll and yaw respectively. With further developments to optimise the system accuracy and its interface, it could be made into a valuable tool for radiotherapy clinics. The outcome of the project has been encouraging, and has shown that augmented reality for patient set-up guidance has great potential.

Thesis (Ph. D.)--University of Canterbury, 2007. / Typescript (photocopy). Includes bibliographical references (p. 211-229). Also available via the World Wide Web.

Thesis (Ph. D.)--University of Washington, 2007. / Vita. Includes bibliographical references (leaves 172-176).

Thesis (Ph. D.)--University of Canterbury, 2008. / Typescript (photocopy). Includes bibliographical references (p. [157]-169). Also available via the World Wide Web.

Thesis (M. Sc.)--University of Canterbury, 2006. / Typescript (photocopy). Includes bibliographical references (leaves 105-114). Also available via the World Wide Web.

Σε αυτή τη διπλωματική θα ασχοληθούμε με κινητά τηλέφωνα νέας γενιάς και με εφαρμογές οι οποίες θα αξιολογούν ένα προϊόν ή μία υπηρεσία και θα επιστρέφουν το αποτέλεσμα με «επαύξηση» της πραγματικότητας στην οθόνη του χρήστη.