Here is some information about current and former research:

User Interfaces for Mobile Augmented Reality Systems

My Ph.D. thesis explores the natural components of, useful services associated with, and user interactions possible with Mobile Augmented Reality. It provides an analytical exploration of this promising new user interface paradigm and presents methodology for the dynamic design and layout of augmented reality user interfaces based on user context.

Augmented Reality (AR), a form of virtual reality that supplements the real world with virtual information rather than creating an entirely synthetic 3D graphical experience, makes for an especially powerful user interface in the mobile computing scenario. Computational services and information can depend on the user's current locale and other types of context, such as time and social situation. A direct coupling of virtual information and real world context is possible. A challenge is the inherent complexity of the AR views when many virtual and physical objects come together in a dynamic world of multiple roaming users and of multiple input and output media.

I developed a hardware/software prototyping environment for mobile AR applications that allows multiple users to participate in collaborative tasks taking place indoors and outdoors. I created exploratory UIs for many different applications and user scenarios. Based on these explorations I developed a taxonomic categorization of mobile AR interface components and their properties. Virtual and real world objects alike are considered as part of the interface. I tag each component with information about its purpose, its intrinsic properties, its relationship to other objects and its capabilities and flexibility with regard to various manipulations. This enables AR interfaces to automatically rearrange themselves in dynamic situations, for example to remove clutter in the augmented view of the world or to make use of additional display capabilities (e.g. nearby wall-sized displays) when these become available.

Visualization

Most of my work in visualization I did at the department of visualization of the Konrad-Zuse-Zentrum (ZIB) in Berlin where I worked from 1992-1995 while finishing my graduate studies at the Technical University of Berlin (TUB). I participated in several research projects: I focused on volume rendering as a scientific visualization method. Most of the computer simulations at ZIB employ finite element methods for the numeric calculations involved. Since these methods use tetrahedral grids to represent the given data on, a visualization method was needed that would work directly on this kind of unstructured grids. This led to the topic of my Diplom thesis: Volume Rendering on Irregular Grids.
Check out my volume rendering page to learn more about the package I implemented and to see some pictures.

My thesis work was supervised by Prof. K.D. Toennies of the computer graphics group at TUB and by H.C. Hege at ZIB.

Here are some by-products of my work in visualization and computer graphics: Visualization Gallery

Natural Language Processing

From September 1991 to December 1993 I worked with the natural language processing group at the TUB in collaboration with the linguistics department. My supervisor was Prof. K. Brockhaus.

I was mainly interested in "new" grammar formalisms dealing with syntactic processing. In accompanying classes and colloquia we also dealt with semantic and knowledge representation issues.

I designed and implemented (in C++) an extensive workbench environment for designing and testing grammars written in the Tree Adjoining Grammar (TAG) formalism. Tree adjoining grammars were invented by A. Joshi and M. Takahashi in 1975. TAGs are interesting because they offer slightly more expressiveness than context free grammars. Their inventors argue that this extra expressiveness is clearly of linguistic relevance. Indeed, there are structures in natural languages that cannot be captured by pure CFGs, but can easily be represented in the TAG formalism.

Apart from the grammar editor and parsing environment (subsequently used by students in the linguistic department), my work resulted in an extensive project thesis titled, A linguistic workbench for the TAG formalism (written in German).

Publications

B. Bell, S. Feiner, and T. Höllerer, View Management for Virtual and Augmented Reality. UIST 2001 (ACM Symp. on User Interface Software and Technology), Orlando, FL, Nov. 11-14, 2001, pp. 101-110.
(Awarded Best Student Paper)
( 4.7MB Acrobat version of paper)

W. Broll, L. Schäfer, T. Höllerer, and Doug Bowman, Interface with Angels: The Future of VR and AR Interfaces. IEEE Computer Graphics and Applications, 21(6), Nov./Dec. 2001, pp. 14-17
( 880KB Acrobat version of paper)

T. Höllerer, S. Feiner, D. Hallaway, B. Bell, M. Lanzagorta, D. Brown, S. Julier, Y. Baillot, and L. Rosenblum, User Interface Management Techniques for Collaborative Mobile Augmented Reality . Computers and Graphics, 25(5), Elsevier Publishers, Oct. 2001, pp. 799-810
( 3.2MB Acrobat version of paper)

T. Höllerer, D. Hallaway, N. Tinna, and S. Feiner, Steps Toward Accommodating Variable Position Tracking Accuracy in a Mobile Augmented Reality System , 2nd Int. Worksh. on Artificial Intelligence in Mobile Systems (AIMS '01), Seattle, WA, August 4th, 2001, pp. 31-37
( 2.1MB Acrobat version of paper)

S. Julier, M. Lanzagorta, Y. Baillot, L. Rosenblum, S. Feiner, T. Höllerer, and S. Sestito, Information Filtering for Mobile Augmented Reality, In: Proc. ISAR '00 (Int. Symposium on Augmented Reality), Munich, Germany, October 5-6, 2000, pp. 3-11

T. Höllerer, S. Feiner, T. Terauchi, G. Rashid, and D. Hallaway, Exploring MARS: Developing Indoor and Outdoor User Interfaces to a Mobile Augmented Reality System , In: Computers and Graphics, 23(6), Elsevier Publishers, Dec. 1999, pp. 779-785
( 2.7MB Acrobat version of paper)( 3.0MB gzipped Postscript version of paper)

T. Höllerer, S. Feiner, and J. Pavlik, Situated Documentaries: Embedding Multimedia Presentations in the Real World, In: Proc. ISWC '99 (Third Int. Symp. on Wearable Computers), San Francisco, CA, October 18-19, 1999, pp. 79-86
( 2MB Acrobat version of paper)( 3.1MB gzipped Postscript version of paper)

A. Butz, T. Höllerer, S. Feiner, B. MacIntyre, and C. Beshers, Enveloping Users and Computers in a Collaborative 3D Augmented Reality, In: Proc. IWAR '99 (Int. Workshop on Augmented Reality), San Francisco, CA, October 20-21, 1999, pp. 35-44
( 1.1MB Acrobat version of paper)( 2.6MB gzipped Postscript version of paper)

S. Feiner, B. MacIntyre, and T. Höllerer, Wearing it Out: First Steps Toward Mobile Augmented Reality Systems, In: Y. Ohta and H. Tamura: Mixed Reality: Merging Real and Virtual Worlds, Ohmsha (Tokyo)--Springer Verlag, 1999, pp. 363-377

A. Butz, T. Höllerer, C. Beshers, S. Feiner and B. MacIntyre, An Experimental Hybrid User Interface for Collaboration, Technical Report CUCS-005-99, Columbia University, 1999.

S. Feiner, B. MacIntyre, T. Höllerer, and A. Webster, A Touring Machine: Prototyping 3D Mobile Augmented Reality Systems for Exploring the Urban Environment, In: Proc. ISWC '97 (Int. Symp. on Wearable Computers), Cambridge, MA, October 13-14, 1997. Also as: Personal Technologies, 1(4), 1997, pp. 208-217
( 131KB Acrobat version of paper)( 2.2MB gzipped Postscript version of paper)

M. Dalal, S. Feiner, K. McKeown, S. Pan, M. Zhou, T. Höllerer, J. Shaw, Y. Feng, and J. Fromer, Negotiation for Automated Generation of Temporal Multimedia Presentations, Proceedings ACM Multimedia, Boston, MA, Nov. 1996, pp. 55-64
( 350KB Acrobat version of paper)( 260KB gzipped Postscript version of paper)

T. Höllerer, Volume Rendering auf irregulären Gittern (Volume Rendering on Irregular Grids), Masters Thesis, Technical University of Berlin, August 1995

T. Höllerer, K.D. Tönnies, H.C. Hege, and D. Stalling, Der Einfluß der Datenapproximation bei Volume Rendering durch ein Emissions/Absorptions-Modell. In: C. Evertsz (ed.): Visualisierung: Dynamik und Komplexität, Bremen, 1995.

T. Höllerer, K.D. Tönnies, H.C. Hege, and D. Stalling, Volume Rendering on Irregular Grids, Abstract, International Workshop on Mathematics and Visualisation, Berlin 1995.

D. Stalling, T. Höllerer, and H.C. Hege, Visualization and 3D-Interaction for Hyperthermia Treatment Planning, Proceedings of CAR '95, Berlin, June 1995, pp. 1216-1222

H.C. Hege, T. Höllerer, and D. Stalling, Volume Rendering - Mathematical Models and Algorithmic Aspects, Technical Report TR 93-7, Konrad-Zuse-Zentrum Berlin, 1993

T. Höllerer, Eine linguistische Werkbank für den Formalismus der Tree Adjoining Grammars (TAG) - (A Linguistic Workbench for the TAG Formalism), Project Thesis, Technical University of Berlin, December 1993

(Last updated: Nov 12 18:21:43 EST 2001)

htobias@cs.columbia.edu