Augmented reality (AR) has become a promising and fast-growing application of computer
graphics over the course of the last years. Augmented reality systems overlay
computer-generated graphical information over the view of the real world. Several main
research challenges can be identified in the field of augmented reality. These are the design
of advanced display devices (e.g., head-mounted displays), camera tracking, system design,
user interaction, and rendering. While a major part of the previous work focused on
the problems of system design, camera tracking, and applications of AR, this thesis puts
a different emphasis on the relatively underrepresented aspect of rendering techniques. In
this thesis, several novel methods for displaying augmented video streams are explored.
In the first part of this thesis in Chapter 2, the design and implementation of a novel
system for medical augmented reality are discussed. The ARGUS framework is a new
augmented reality system based on a commercial surgical navigation device. Since it does
not require any additional hardware components, a transition into the clinical practice can
be facilitated. Several extensions of the basic framework are described, including a hybrid
tracking scheme, a user interaction library, and amethod for handling occlusion. The latter
algorithm makes it possible to correctly render the occlusion of graphical objects by the
anatomy of the patient, leading to a more realistic and easily comprehensible output. This
approach is one of the advanced rendering methods for augmented reality investigated in
the context of this thesis.
The second part of this thesis, Chapter 3, introduces the concept of stylized augmented
reality, which applies artistic or illustrative stylization methods to augmented reality video
streams. Since the same type of stylization is applied to virtual and real scene elements,
they become difficult to distinguish. This way, a novel augmented reality experience
is created, and possibly even a better immersion. Real-time algorithms for cartoon-like
and painterly brush stroke stylization of augmented video streams are described. The
exploitation of programmable graphics hardware for this purpose is discussed. Moreover,
the results of a psychophysical study on the discernability of virtual objects in stylized
augmented reality are presented.
At the beginning of Chapter 4, which is the third part of this thesis, a novel illustrative
visualization method is described. This new rendering algorithm for iso-surfaces
and polygonal models generates an illustrative representation of a surface and structures
hidden behind it. The method is designed for the programmable rendering pipelines of
modern graphics hardware and is capable of displaying complex models in real-time. An
extension of this newly developed illustrative display style was also applied to augmented
reality video streams. This system constitutes another realization of the concept of stylized
augmented reality.
Bibtex
@PHDTHESIS{Fischer-2006-PhdThesis,
AUTHOR = {J. Fischer},
TITLE = {{Rendering Methods for Augmented Reality}},
SCHOOL = {{University of T{\"u}bingen}},
YEAR = {2006},
TYPE = {Dissertation}
}