Uwe Hahne

	address:	Sekretariat EN 7-1 Fakultät Elektrotechnik & Informatik Technische Universität Berlin Einsteinufer 17 10587 Berlin
	phone:	+49 30 314-73103
	fax:	+49 30 314-23596
	email:	uwe.hahne (at) tu-berlin.de
	office&hours:	E-N 709, whenever the door is open

Since July 2006, I am working as a PhD student in the Computer Graphics Group of Prof. Marc Alexa at the Technical University Berlin.

I graduated with honors in Computer Science and Media at the Bauhaus University in Weimar in June 2006. Since then, I may call myself a "Diplom-Mediensystemwissenschaftler". As this degree program has been changed to a BSc program meanwhile, there are only very few people bearing this exceptional title.

Projects

Recent:

This is a list of topics I currently work on at TU Berlin.

		Combining Time-Of-Flight with Stereo I work on this topic for about two years. It all started with the student project Scanning real world objects without worries. Subsequently, I supervised the diploma thesis of Antoine Mischler who focusses on real-time stereo and depth estimation for augmented reality applications. More information the project can be found here. Don't hesitate to contact me if you are interested in my work.

Combining Time-Of-Flight with Stereo

I work on this topic for about two years. It all started with the student project Scanning real world objects without worries. Subsequently, I supervised the diploma thesis of Antoine Mischler who focusses on real-time stereo and depth estimation for augmented reality applications. More information the project can be found here. Don't hesitate to contact me if you are interested in my work.

Exposure Fusion for Time-Of-Flight Imaging

Based on previous findings from other time-of-flight projects and some ideas from the computational photography course, I realized an approach to enhance the dynamic range of depth maps. See the project website for more information.

Multi-touch

I also do some research on multi-touch. We built a multi-touch table during a course project with a couple of students. See the project website for details and feel free to contact me in order to get more information.

Weimar:

This is a list of projects and seminar works I realized during my studies in Weimar.

		Diploma thesis: "Weighting in Laplacian Mesh Editing" This diploma thesis has been created in cooperation with DaimlerChrysler. A software has been developed that supports the assembly simulations performed by design engineers. An assembly simulation examines the collision of units. These virtual units are presented as triangular meshes and they are currently solid and undeformable in contrast to real world objects. This software simulates the natural solidness of the units by allowing to deform the virtual objects in a natural manner. To do this, a Laplacian mesh editing scheme has been implemented. Laplacian mesh editing allows to deform 3D objects while their surface details are preserved. Detail preservation is an important feature because it allows the simulation of realistic deformations. The thesis focuses on examining the effects of different weighting schemes for a Laplacian mesh editing method. This method supports the assembly simulation which is performed during the phase of construction in automotive design. Thus, it has been adapted to the special requirements of such an application by the use of different weights. The deformations are computed by the help of a minimisation method. The present work describes the usage of alternative weights within these minimisation and its effects. In addition, an automatic weighting method has been developed that allows rapid editing tasks. Full text (pdf) Presentation slides (pdf) Video: Bunny (avi) Video: Sphere (avi)

Diploma thesis: "Weighting in Laplacian Mesh Editing"

This diploma thesis has been created in cooperation with DaimlerChrysler. A software has been developed that supports the assembly simulations performed by design engineers. An assembly simulation examines the collision of units. These virtual units are presented as triangular meshes and they are currently solid and undeformable in contrast to real world objects. This software simulates the natural solidness of the units by allowing to deform the virtual objects in a natural manner. To do this, a Laplacian mesh editing scheme has been implemented. Laplacian mesh editing allows to deform 3D objects while their surface details are preserved. Detail preservation is an important feature because it allows the simulation of realistic deformations.
The thesis focuses on examining the effects of different weighting schemes for a Laplacian mesh editing method. This method supports the assembly simulation which is performed during the phase of construction in automotive design. Thus, it has been adapted to the special requirements of such an application by the use of different weights. The deformations are computed by the help of a minimisation method. The present work describes the usage of alternative weights within these minimisation and its effects. In addition, an automatic weighting method has been developed that allows rapid editing tasks.

Full text (pdf)

Presentation slides (pdf)

Video: Bunny (avi)

Video: Sphere (avi)

Optical Tracking

During two projects we worked on tracking input devices for virtual reality applications. In the first part, we tracked LEDs an reconstructed their position in 3D space with a multi view setup of several small firewire cameras. In the second part, we worked on tracking colored objects with a single camera and on computing the position of a rack of laser pointers by tracking their light spots and calculate back their origin.

German documentation of the first part.

Final presentation slides of the second part.

Gasblasen

In industry gas bubbles are used to clean oil. The path of these bubbles want to be predictable. In our project we analyzed the path of a bubble in a water tank captured by two video cameras. We described the path as a spiral in order to minimze the error while having a simple description of the path of any further bubble in any other liquid. Unfortunately, we never received more data to prove our system.

German documenation

Final presenation slides (also German)

Holographics

First, I did some research on digital holography. In order to print a hologram we took a picture of a car's headlamp from each viewing angle (see video). The whole process is described in the term paper and the slides of our presentation. I joined the holographics research project in 2004. The aim of the project was to combine holograms with interactive computer graphics. See the website and the following paper for details:

Bimber, O., Zeidler, T., Grundhöfer, A., Wetzstein, G., Möhring, M., Knödel, S., and Hahne, U. "Interacting with Augmented Holograms". In proceedings of SPIE Conference on Practical Holography XIX: Materials and Applications, January 2005

Publications
2011: Exposure Fusion for Time-of-Flight Imaging; Hahne, U. & Alexa, M.; Computer Graphics Forum, Volume 30 - Issue 7, pp. 1887-1894; Presented at Pacific Graphics 2011, Kaohsiung, Taiwan; Slides (PDF, 2,4 MB) Paper (PDF, 1,8 MB)
2009: Depth Imaging by Combining Time-of-Flight and On-Demand Stereo; Hahne, U. & Alexa, M.; Dynamic 3D Imaging, Springer, 2009, Vol. 5742, pp. 70-83; Video (MP4, 21,3 MB) Slides (PDF, 1,9 MB) Paper (PDF, 4,9 MB); Multi-touch focus+context sketch-based interaction
Uwe Hahne, Jonas Schild, Stefan Elstner, Marc Alexa
SBIM '09 Proceedings of the 6th Eurographics Symposium on Sketch-Based Interfaces and Modeling, 2009
Slides (PDF, 1,0 MB) Paper (PDF, 228 KB)

frames are not supported
2008: Continuous reference images for FTIR touch sensing; Alexa, M., Bollensdorff, B., Bressler, I., Elstner, S., Hahne, U., Kettlitz, N., Lindow, N., Lubkoll, R., Richter, R., Stripf, C., Szczepanski, S., Wessel, K. & Zander, C.; SIGGRAPH Posters, 2008, pp. 49; Poster (PDF, 706,8 KB), Abstract (PDF, 527,7 KB), Video (MOV, 26,0 MB); Combining Time-Of-Flight depth and stereo images without accurate extrinsic calibration; Hahne, U. & Alexa, M.; Int. J. Intelligent Systems Technologies and Applications, 2008, Vol. 5(3/4), pp. 325-333; Paper (PDF, 688 KB)
2007: Combining Time-Of-Flight Depth and Stereo Images without Accurate Extrinsic Calibration; Hahne, U. & Alexa, M.; International workshop on Dynamic 3D Imaging, 2007, pp. 78-85, published as journal paper in IJISTA 2008; Slides (PDF, 582 KB)
2005: Interacting with Augmented Holograms; Bimber, O., Zeidler, T., Grundhoefer, A., Wetzstein, G., Moehring, M., Knoedel, S. & Hahne, U.; SPIE Conference on Practical Holography XIX: Materials and Applications, 2005; Paper (PDF, 831 KB)

Teaching

SS 2011:

MPGI 2 - Methodic and practical basics in computer science (part 2), together with Clemens Eppner and Sebastian Höfer, I lead a group of student tutors for organizing and executing the tutorials for this first year (2nd semester) course. I filled in for Prof. Oliver Brock for some lectures on graph theory.

Processing Digital Camera Images - A seminar about processing camera images in a modern way. I again supported Mathias Eitz in organisation and leading the seminar. My part was to organize the basic talks of the students.

WS 2010/11:

Computer Graphics 1 - A basic course along the rendering pipeline. I supported Ronald Richter with the exercises.

SS 2010:

No teaching due to parental leave.

WS 2009/10:

Processing Digital Camera Images - A seminar about processing camera images in a modern way. I supported Mathias Eitz in organisation and leading the seminar.

SS 2009:

Computational Photography - A project in conjunction with the University of Arts (UdK) Berlin

MPGI 2 - Methodic and practical basics in computer science (part 2), I again lead a group of several teaching assistants organizing and executing the tutorials for this first year (2nd semester) course.

WS 2008/09:

Depth Imaging - A project course about combining time-of-flight depth imaging with color imaging.

SS 2008:

MPGI 2 - Methodic and practical basics in computer science (part 2), I lead a group of several teaching assistants organizing and executing the tutorials for this first year (2nd semester) course.

WS 2007/08:

Multi-Touch Display - co-organizing with Marc Alexa

MPGI 1 - Methodic and practical basics in computer science, I work in a group of several teaching assistants organizing and executing the tutorials for this first year course.

SS 2007:

Computer Graphics/Computer Vision - Basic course

A basic course about cg and cv which is realized together with the CV group. I organized the exercises together with Ulas Yilmaz. During this course a panorama tool has been implemented by the students.

WS 2006/07:

Scanning real world objects without worries - co-organizing with Marc Alexa