site shows a selection of projects I was working on during my
studies at the University
of Magdeburg. Many of them are class projects from my
student time, while others originate from the work as research
assistant in the various departments. The list has been loosely divided
into undergrad/Master projects and PhD projects, see below. Some of the
projects were developed and implemented in groups, or with the help of
others. The names of the people involved, as well as project related
publications are listed. If you have any questions or
comments, please feel free to contact me.
Accompanying publications can be found here.
(Niklas Röber, Michael Schild)
this undergraduate project, we developed a
capturing and image analysis tool for neurological sciences.
It allows to
visually capture and measure the brain functions of gerbils that were
exposed to acoustic stimuli.
Therefore, the program enables on to setup an experiment of acoustic
stimuli, to carry out the experiment, and later to analyze and
resulting data. The program drives a special parallel-port hardware
device and the camera system. The implementation was done using C++.
Screenshot of the CapConNT system
(Niklas Röber, Dennis Kurz)
Another project was devoted
to explore the
possibilities for cognitive learning in
The goal was to develop a program, which can assist
athletes in correctly learning and training sport techniques. The
program was initially created for Judo, but can easily be adopted to
other sports. The user simply has to create the correct movements out
of pre-rendered images, animations and 3D visualizations.
The movement data was captured using an optical motion
capturing system and transferred to an artificial character in 3D
2.5. In order to make use of the animation data, an exporter Plug-in
had to be developed for 3D Studio Max. The progress of the learning
process is displayed intuitively using graphics and also
interfaced with an EEG system
to measure the advances more precisely. The software itself is
developed using Delphi and used since its development with great
the cognitive learning
During my 7 month
internship with the Medical
Imaging Research Group
at the Vancouver General Hospital in 1999/2000,
I developed an analysis and visualization environment for dynamic SPECT
data sets. This software allows to render the data in many variations,
including iso-surfaces, traditional slices and volume rendering.
The user can freely interact and slice the data set, as well as perform
basic image and volume processing tasks to enhance the data, or to
visualize certain parts in detail. Several Volumes-of-Interest
can be segmented and analyzed semi-automatically. The results are
displayed using time-activity-curves. Also animations can be created,
either the entire data set or changes of specified parameters.
Additional volume data, such as displaying morphological information,
can also be combined with the functional dSPECT data set. The software
was developed on a Macintosh using IDL 5.0.
See the report here.
Screenshot of the dSPECT analysis and visualization system
This program was developed
with Gerald S. Zavorsky and Dr. Sexsmith from St. Paul's Hospital and
the University of British Columbia in Vancouver, Canada. Gerry was
working on his Ph.D. about: "Acute
hypervolemia lengthens pulmonary
transit time during near-maximal exercise in endurance athletes with
exercise-induced arterial hypoxemia".
program allows to
determine several parameters from nuclear medicine studies, including:
- Cardiac Output
- Ejection Fraction of the Left
- Stroke Volume
- End Systolic Volume
- FWHM (Full Width Half Max)
- Pulmonary Capillary Transit Time
- PBV Index and more...
the Cardiac analysis system
CD's and short Films
(Niklas Röber, Martin Spindler,
Cosme Lam, Alf Zander, Jens Hasenstein ...)
of some University projects and classes, several Multimedia CD's (3)
films (4) were created. The majority of these projects was related to
education, philosophy and human interaction. Additionally, an extensive
advertisement campaign for the fake product "Bauschaum2000"
(insulation foam), including 2 video ads, a large poster and a website
were designed and created. The Multimedia
CD's were designed and implemented using standard CD authoring
software, including Macromedia
Director and RSE Author. The films were filmed and arranged digitally,
using Adobe Premiere and After Effects, as well as discreets
combustion* for post-processing.
the film "aspiration"
(Niklas Röber, Maic Masuch, ...)
As part of my research
assistantship at the
Department for Simulation and Graphics from 1998-2001,
I was responsible for the modeling, texturing and animation of an
excavated scene and the resulting virtual reconstruction of an ancient
building. In the 1960's archaeologists discovered remains from a
building, which was long believed to be the palace of Otto-the-Great,
one of Europe's biggest emperors in the middle ages. Several
reconstructions were created and in 2001 exposed to the public as part
of an exhibition in the local museum. The exhibition got the
title of an "Exhibition
of the European Council", as well as the
patronage of the German Federal President, Johannes Rau. In early 2000,
researchers discovered that the believed palace was a cathedral and, as
a result to integrate some uncertainty into the renditions, NPR
were used in the visualizations to show the varying knowledge of the
absolute shape of the building.
the accompanying publication here.
photo-realistic rendition from the Kasierpfalz project
Rendering using OpenGL
a coop student in the last semester, I
implemented several NPR techniques into the freely available
OpenGL-based 3D game
engine Fly3D. These NPR techniques could also be used to
visualize uncertainty for our virtual reconstructions (see
previous project). All
rendering styles can be combined in the same scene and are rendered in
real-time. The techniques implemented include classic cartoon
rendering, z-coloring, line-dithering, warm/cold rendering, as well as
tonal art maps.
See the report
rendering styles in a game engine
This project focused on the
parametric displays that show the direction and strength of flow in a
human kidney. Here flow information from dSPECT data sets were
extracted and interpolated and visualized using 3D glyphs and
hefgehogs. The vectors are computed by using a flow-simulation
model. Every voxel
is assigned to a specific volume-of-interest. Using this information
the given time-activity-curve for this voxel one can determine average
vectors, which are fitted to the data set in a second iteration
step. For some tissues, like the ureter, the flow is periodic,
because the urine is collected in the kidney basin
for a while and then released. For this tissue the flow direction is
constant, but the speed changes.
flow is computed by using the initial average flow from
each voxel, the flow direction of neighboring voxels and also from the
of change, acceleration and deceleration, of the activity. The
vectors represent the flow of the activity and visualize the organs
accompanying publication here.
visualization showing the flow of activity through a human
Master's Thesis I was working on visualization techniques for large
volumetric data sets. This research was conducted in the Graphics Lab
at the Simon-Fraser-University in Vancouver, Canada. I used
programmable graphics hardware to compute the final visualizations.
Using the latest developments, high quality graphics could be achieved
at interactive frame rates.
a pre-processing step, the data was loaded and eventually resampled to
a more efficient lattice (BCC, D4*). Furthermore, larger data sets were
decomposed using wavelets for LOD rendering and also broken up into
bricks, if the entire data set would not fit in the targeted graphics
memory size. After this processing, the data can be loaded into the
visualization system, where the usual volume rendering techniques, such
as direct volume rendering, iso-surfaces with and without shading,
x-ray rendering and maximum intensity projections are available. Also
animations of time-varying data sets can be created. The rendering
itself was implemented using graphics hardware, eg. 3D textures and
studies were preformed to prove the efficiency of the system.
Additionally, and because of a later shifted focus of the thesis,
multi-parameter visualization techniques of fuel cell simulations were
analyzed and prototypically implemented using the VTK toolkit for
visualization and rendering.
See the report here.
the volume rendering system displaying the frog CT dataset
my time as PhD student I was involved into and also managed and
administered several projects. The majority of them were of
related to my main research topic, but also other and
areas were covered. Most of the here presented projects represent
teamwork and were developed and implemented with colleagues, and
undergrad/grad students as part of their studies and supervised
internships. All names are listed and the projects accompanying
publications are listed on the publications
(Niklas Röber, Daniel Walz,
Andre Miede, Jörg Futterlieb)
environments can be seen as the acoustic analog to the more general
audio/visual environments. The goal here was to determine
and evaluate suitable sonification and interaction techniques to
acoustically convey information and to intuitively interact with 3D
auditory spaces. Although the areas of application were not limited, a
slight focus lay on entertainment and edutainment fields.
An extensive analysis of the existing techniques, followed by a
prototypic implementation for further testing and evaluation, resulted
in the design of a new audio framework on the basis of OpenSG and
OpenAL. This framework was initially only equipped with several basic
sonification and interaction techniques, which grew and evolved over
time with following projects. An authoring of the 3D auditory scenes
could be performed using 3D Studio MAX for 3D scene authoring and VRML
for setting up the auditory properties.
of a 3D auditory environment
(Niklas Röber, Mathias Otto,
using the audio framework from the last project, we designed and
developed 4 simple audio-only computer games. Here we additionally
employed a head tracking device (Polhemus Fastrak), a webcam and a
regular gamepad for input and user interaction. Three of the games were
action games, and a fourth one an auditory adventure playing in the
cathedral of Magdeburg:
- Audio Frogger
(acoustic version of the legendary Frogger game)
(catch up to three mosquitoes flying around your head)
(evade virtual acoustic bullets in a most artistic manner)
hidden Secret (auditory adventure game)
were tested by sighted and also by visually impaired people. Although,
the games are fun to play, one needs to hear-in
for a while, as especially sighted users are not used to rely on
hearing as much. Difficulties also occurred with the 3D audio
adventure, as the orientation and navigation within 3D auditory spaces
turned out to be very challenging.
much to see in an audiogame)
and Cartoon Rendering
(Niklas Röber, Robert Döhring,
and cartoon rendering is especially suited for the graphic display in
computer games, as it communicates a different reality, in which
different possibilities and characteristics exist - different
to our own. Unfortunately, the cartoon rendering style used in games
limits itself to only a very basic implementation. This project focused
on an extension of the existing cartoon rendering through inspirations
from the SinCity
comic books. Several techniques could be adapted and integrated into a
3D game engine, such as double contour lines, inverse shading,
hatching, stylistic shadows, pseudo edges through soft cell shading,
and of course the classic cell shading approach.
a simple analysis of camera styles and movements were
also integrate these characteristics within a game engine and computer
showing a SinCity inspired Cartoon rendering style
(Niklas Röber, Cornelius Huber)
Audiobooks aim to combine the potentials of complex (non-)linear
narratives (eg. books and radio plays) with interactive elements from
computer games. The design thereby concentrates on a flexible
degree of interaction in a way that the listener's experience ranges
anywhere from a passive listening to an interactive audio-only computer
game. The story branches at important points, at which the listener can
direction to pursue. Several smaller minigames are scattered throughout
the story and the listener/player can take an active part in the story.
These interactions are, however, not required, and the Interactive
Audiobooks can also be listened to just as regular audiobook.
the Interactive Audiobooks authoring environment
(Niklas Röber, Eva Deutschmann,
audio reality combines a real world environment with an artificial
auditory environment. This artificial auditory space can contain
additional information, and be used for entertainment, eg. in games, to
guide visually impaired people, or also as tourist information system.
Within this project, a low-cost augmented audio system on a PC basis
and developed, along an authoring environment and several smaller
applications to demonstrate its function and applicability. Here a self
developed WLAN-based user tracking system is employed, which allows a
tracking precision of 2-3 meters within building.
digital compass and a gyro mouse is employed to facilitate user
interaction. Two examples scenarios have been implemented, but need to
be tested more extensively. One is an adaptation of "The hidden
Secret", which has been used in an audio adventure game, but also
as story for an Interactive Audiobook.
from the authoring environment for augmented audio reality
room acoustics is concerned with the numerically evaluation of the wave
equation in order to simulate sound wave propagation. The digital
waveguide mesh is an extension of the original 1D technique and
constructed by bi-linear delay lines that are arranged in a mesh-like
structure. Higher dimensions are built by scattering junctions that are
connected to the delay lines and act as spatial and temporal sampling
points. The equations that govern the rectilinear waveguide mesh are
based on difference equations derived from the Helmholtz equation by
discretizing time and space. Due to a required oversampling and the
short wavelength of the higher frequencies, such meshes can easily
become quite large. Additionally, in order to perform a realtime
simulation, an update rate is required similar to the targeted sampling
project evaluated the possibilities to exploit graphics hardware for
wave-based sound simulations, by solving the difference equations using
3D textures and fragment shaders. The results were quite impressive and
showed a possible acceleration by a factor of up to 20-30.
simulations based on waveguide meshes
Sound Rendering and Filtering
(Niklas Röber, Ulrich Kaminski)
graphics hardware, especially with the new unified shader architecture,
is very well suited for the manipulation and filtering of digital
signals. Using a stream processing approach, up to 128 signals can be
filtered, analyzed and manipulated in parallel. The hardware's
architecture hereby also allows a fast and efficient storage and access
of data in graphics memory, which is of equal importance. This project
evaluated the possibilities for
a graphics-based sound signal processing, also in close connection with
the following project. Here, several simple time-based and
frequency-based filters were implemented employing the GPU as a general
DSP. The implemented filtering techniques include a 10-band equalizer,
chorus, reverb, pitch change and many more, but also FIR convolutions,
as used in room acoustics and for 3D sound spatialization.
sound signal processing
Rendering and Rayacoustics
(Niklas Röber, Ulrich Kaminski)
employed approach for the simulation of room acoustics is to
approximate sound waves through particles that are moving along
directional rays. These rays are traced through a virtual scene
starting at the listener's position, at which later the accumulated
energy is evaluated and used to determine the virtual
As sound waves are now simplified as rays, wave phenomena and
differences in wavelength are generally discarded and ignored. This
project analyzes sound propagation in terms of acoustic energy and
explores the possibilities to map these concepts to radiometry and
graphics rendering equations. Although, the main focus is on ray-based
techniques, also wave-based sound propagation effects are
partially considered. The implemented system exploits modern graphics
hardware and rendering techniques and is able to efficiently simulate
3D room acoustics, as well as to measure simplified personal HRTFs
through acoustic raytracing. This project also uses the GPU as sound
DSP to create a binaural signal with the virtual rooms acoustic imprint.
simulations based on acoustic raytracing
(Niklas Röber, Ulrich Kaminski,
and precise HRTFs are very important for 3D sound spatialization, as
they enable the listener to determine a sounds origin in 3D space.
Unfortunately, these HRTFs vary from person to person with the shape of
the head and the outer ears. So far, no techniques are available that
allow a simple and intuitive personalization or user accommodation of
existing HRTFs. One promising approach is here to simulate these HRTFs
using geometric models. Although, this requires a second technique to
acquire a geometric model of the user's ear, it would also allow to
perform a simulation to measure
HRIRs/HRTFs. These can later be used for a real personalized 3D sound
we compared two different approaches; an offline ray-acoustic
simulation using the POV-Ray rendering system, and a more real-time
implementation using programmable graphics hardware.
ray-based HRIR simulations
Data/Volume Sonification and Interaction Techniques
(Niklas Röber, Lars Stockmann,
majority of data and information in today's world is represented
visually using color and graphical primitives. This not only overloads
the visual channel, but also ignores that some data is best represented
using auditory cues and certain sonification techniques. The goal of
this project was to explore the possibilities, but also the
limitations, of data and volume sonification techniques. Several
prototypes were developed and compared for the tasks of stock data
sonification, the sonification of 2D shapes and 3D objects, as well as
for an acoustic representation of 3D volumetric data sets. A parallel
sonification of multiple stack data sets was thereby implemented using
spatialization and a rhythmic sequencing, while the sonification of 2D
shapes and 3D objects/volumes was based on an auditory scanline,
respective a 3D auditory chimes. A additional user evaluation approved
the developed techniques and has shown that a sonification of 2D and 3D
data sets is possible even by untrained ears.
of a volumetric data set using an auditory chimes
my first years in Hamburg I started a distant learning University program at the Fernuniversität Hagen / University of Wales.
The co-organized MBA program focussed on the subjects of finance &
controlling, with courses and workshops at the Fernuni Hagen, and an
MBA thesis at the University of Wales.
Simulation-based Business Valuation
process of company valuation is a daily business that is employed every
day many times for various reasons. A variety of different methods and
techniques have been developed and evolved over the years to perform
business valuation. Each method has its own advantages and drawbacks.
However, all methods share that they are based on uncertain data, which
is used to perform the business valuation in order to determine the
most realistic value for a specific company.
The goal of this
Masters thesis is the evaluation of classic valuation techniques, and
their extension towards a simulation-based business valuation by
employing stochastic optimization processes. Two simulation techniques
are used, the common Monte-Carlo simulation, as well as a particle
swarm optimization method. Both simulations are extended to perform
business valuation using the discounted cash flow method.
The thesis is available in German at this page
fig.21 Business valuation of Google Inc. using a
Monte Carlo Simulation (in Million US$)