Projects


Ultrasound Localization Microscopy

Super-resolution Ultrasound Imaging

Ultrasound Localization Microscopy

Ultrasound Localization Microscopy (ULM) is an innovative super-resolution technology in the field of medical ultrasound imaging. In a collaborative project with researchers from the Sorbonne Université (Paris, France), this work aims to develop a rapid and precise ULM method by exploiting the potential of raw data with our geometric deep learning framework. The video presents accumulated localization frames in slow motion with an exponential acceleration of the frame rate for improved rendering comprehension.

Journal preprint
Conference preprint

  • Role: Author & Developer
  • Years: 23/24

PaCE

Parallax among Corresponding Echoes

Parallax among Corresponding Echoes

This study introduces a novel 3-D Time-of-Flight localization model named Parallax among Corresponding Echoes (PaCE), which has been accepted as a paper for publication at ICRA. The prototype only consists of one acoustic emitter and three receivers to locate a target moved by a robot. This technology has immense potential to be an alternative or extension to phased-arrays. The IP is managed by unitectra. Please feel free to reach out with any questions or opportunities for collaboration.

  • Role: Author & Developer
  • Year: 2023

torchimize

Numerical Optimization Algorithms in PyTorch

torchimize

torchimize offers parallelized numerical optimization methods for PyTorch data types. The main motivation for this project is to enable convex optimization on GPUs based on the torch.Tensor class, which (as of 2022) is widely used in the deep learning field. This package features multiple cost aggregation and is capable of minimizing several least-squares optimization problems at each loop iteration in parallel.

  • Role: Author & Developer
  • Year: 2022

Expectation Maximization

Image Segmentation

Expectation Maximization

In this work, the famous Expectation Maximization (EM) algorithm is demonstrated in detail while applying it as an unsupervised image clustering technique.

  • Role: Author & Developer
  • Year: 2021

Multiple View Imaging

Depth Rendering in Computer Vision

Talk on Multiple View Imaging

In 2021, I gave an academic talk at the ARTORG Center (University of Bern) to present a research overview on stereo vision and 4-D light-field rendering algorithms. The slides can be found here.

  • Role: Author & Speaker
  • Year: 2021

optimizay

numerical optimization methods

optimizay

optimizay is an online repository in which root-finding and numerical optimization methods are distilled to interactive Jupyter notebooks.

  1. Univarite Newton-Raphson Minimization
  2. Bivariate Gradient Descent vs. Newton-Raphson
  3. Bivariate Newton Root-finding
  4. Conjugate Gradient
  5. Gauss-Newton vs. Levenberg-Marquardt
  6. Stochastic Gradient Descent (SGD)
  7. Feature Engineering - Titanic
  8. Expectation Maximization

  • Role: Author
  • Year: 2020

depthy

depth map computation

depthy

depthy enables depth reconstruction from multiple views while supporting *.pfm and *.ply file exports to store a 2-D depth map or 3-D point cloud.

  • Role: Developer
  • Year: 2020

color-matcher

automatic color-grading



Source Target Result

color-matcher

color-matcher enables color transfer across images which comes in handy for automatic color-grading of photographs, paintings, film sequences or light-fields.

  • Role: Developer
  • Year: 2020

Talk on PlenoptiCam at #GPN

Gulaschprogrammiernacht

Talk on PlenoptiCam at CCC's Gulaschprogrammiernacht

This talk unveils the underlying physical and computational concept of the Lytro-type plenoptic camera in a concise and simplified manner while presenting an open-source software tool capable of rendering light field photogaphs.

Plenoptic cameras and their ability to change focus and perspective view after the fact has intrigued scientists, programmers, photographers and tech-hobbyists world-wide. With this presentation, the fundamentals of a light field captured by a plenoptic camera are provided to a broader audience without requiring prior knowledge of such. It is of primary interest to raise awareness of this technology and invite peers to contribute to presented open-source software tool [PlenoptiCam](https://github.com/hahnec/plenopticam). More technical details and further educational material is found on my research website https://www.plenoptic.info.

  • Role: Speaker
  • Year: 2019

PlenoptiCam

Light field photography software
bottom image
Animation

PlenoptiCam

This open-source software enables lightfield rendering of raw image captures taken by a plenoptic camera such as that from Lytro. It is available for download on GitHub. The groundwork for this project was laid in my doctoral thesis.

  • Role: Software Developer
  • Year: 2019-2021

PlenoptiSign

Light field geometry design tool
plenoptisign

PlenoptiSign

This open-source application is meant to help understand mechanisms of a plenoptic camera and to support at their conceptual development stage. It can be downloaded from GitHub or run on my research website. The groundwork for this project was laid in my doctoral thesis.

  • Role: Software Developer
  • Year: 2019

Light Field Research

Standard Plenoptic Ray Tracing Model
Light field camera

Standard Plenoptic Ray Tracing Model

While being a research fellow at Brunel University as well as the University of Bedfordshire, I came up with the Standard Plenoptic Ray Tracing Model which describes light rays travelling through a plenoptic camera. Based on geometrical optics, the proposed model helps understand the idea of computational refocusing and estimating the refocusing distance just as determining the baseline of the camera. Besides, related work on this project presented the first hardware architecture to accomplish real-time refocusing for a plenoptic camera.

  • Doctoral Advisors: Prof. Amar Aggoun, Dr. Vladan Velisavljevic
  • Role: Ph.D. candidate
  • Years: 2012 - 2016

Affiliations


ARTORG Center - University of Bern

2021 - present
ARTORG Center

ARTORG Center - University of Bern

Since September 2021, I have been affiliated with the ARTORG Center, which is part of the University of Bern. We aim to push the boundary in next-generation surgical robot navigation with an industry leading partner.

  • Role: PostDoc - Artificial Intelligence in Medical Imaging (AIMI)
  • Years: 2021

trinamiX

2016 - 2019 & 2021
trinamiX

Adaptive 3D Sensing - trinamiX

In February 2016, I joined the trinamiX GmbH which is a wholly owned subsidiary of BASF. Founded in 2015, trinamiX aims at developing cutting-edge sensor technology. My responsibilities included research on laser imaging and image processing algorithms.

  • Role: Senior Computer Vision Engineer - Algorithms & Machine Learning
  • Years: 2016 - 2019 & 2021

Pepperl+Fuchs

2019 - 2021
p+f

Ultrasonic sensing - Pepperl+Fuchs

I started working for Pepperl+Fuchs SE in March 2019 focusing on depth reconstruction algorithms and synthetic aperture modeling for multi-channel ultrasonic sensor data.

  • Role: Development Engineer - Technology & Innovation Unit (T&I)
  • Years: 2019 - 2021

University of Wolverhampton

2019
UoW

Plenoptic Cameras - University of Wolverhampton

Short stay to finish off research projects on plenoptic cameras.

  • Role: Visiting Scholar - School of Mathematics and Computer Science
  • Year: 2019

University of Bedfordshire

2015
GeoStick

Commissioned work - University of Bedfordshire

Development of a software application which first acquires geometrical information about a captured scene and then provides physical distances to the user. The work was commissioned by Morrison Utility Services.

  • Client: Morrison Utility Services (UK)
  • Supervisor: Dr. Vladan Velisavljevic
  • Role: Software developer
  • Year: 2015

About

I am an Advanced Postdoctoral Researcher affiliated with the AI Medical Imaging (AIMI) Group at the ARTORG Center as part of the University of Bern. My current research interests concentrate on algorithm development in the fields of computer vision, audio processing and depth sensing.

During undergraduate studies at the University of Applied Sciences in Hamburg, I began my professional career as an intern in R&D departments of companies such as Rohde & Schwarz, where I was evaluating digital video transmission protocols, and Arnold & Richter (ARRI) starting with research on plenoptic cameras.

When graduating in 2012, I enrolled for a guest studentship at Brunel University in West London. This led to an MPhil course, supervised by Prof. Amar Aggoun, to pursue plenoptic camera research with the development of an FPGA-based refocusing technique.

To accompany my doctoral advisor Amar, I transferred to the University of Bedfordshire in 2013 where I carried out image processing research in a bursary-funded PhD programme. During that time, I taught a Master's course in Embedded Systems using C programming, supervised postgraduate dissertations, developed software prototyping for commissioned work and built up a profound understanding in algorithm development, signal processing, parallel computing and English as a foreign language.

While finishing my doctoral studies in the UK, I was approached by the newly founded trinamiX GmbH, a subsidiary of BASF SE in Germany, which I happily joined in 2016. After three exciting years at the German spin-off, I then had the opportunity to conduct research on acoustic signal algorithms for the Pepperl+Fuchs SE based in Mannheim (Germany), which resulted in the complete prototype development of an ultrasound phased array.

“A good engineer thinks in reverse and asks himself about the stylistic consequences of the components and systems he proposes.” Helmut Jahn
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