Dr. Erdem Altuntac

'Everything should be made as simple as possible, but not simpler.'

Albert Einstein.

I am currently research scientist at Fraunhofer FHR after my 2 years of PostDoc research at the Universite Libre de Bruxelles, under the supervision of Prof. Dr. I. Loris. I obtained my Ph.D. in April 2016 under the supervision of Prof. Dr. D. R. Luke and Prof. Dr. T. Hohage. My detailed scientific activities are below.

Research Interest

Modeling & Algorithms

  • Constrained non-linear convex optimization
  • Dictionary-based sparse representation;

    • Orthogonal representation bases, i.e. wavelets, DCT, DFT
    • Image based dictionaries

  • Iterative variational regularization methods for inverse ill-posed problems;

    • Conventional quadratic-Tikhonov regularization
    • Gradient-based algorithms
    • Primal-dual splitting
    • Proximal mapping
    • Rules for the choice of the regularization parameter
    • Convergence analysis (with the assumption of Variational Source Condition).


    • Depth completion from LiDAR based point-cloud data
    • Image inpainting
    • Computational image recovery
    • Multidimensional tomographic image reconstruction; e.g. 3D atmospheric tomography
    • Situational awareness by acoustics
    • Parameter estimation in non-linear acoustics


    • Cwalina, S., Kottke, C., Jungnickel, V., Freund, R., Runge, P., Rustige, P., Knieling, T., Gu-Stoppel, S., Albers, J., Laske, N., Senger, F., Wen, L., Giovanneschi, F., Altuntac, E., Rames, A. N., Huici, M. A. G., Küter, A., Reddy, S. Fiber-based frequency modulated LiDAR with MEMS scanning capability for long-range sensing inautomative applications. (to be presented at IEEE MetroAutomotive Workshop 2021) .

    • Altuntac, E. Choice of the Parameters in A Primal-Dual Algorithm for Bregman Iterated Variational Regularization.
      https://doi.org/10.1007/s11075-020-00909-6 Numer Algor 86, 729–759 (2021).

    • New Pair of Primal Dual Algorithms for Bregman Iterated Variational Regularization.
      https://arxiv.org/abs/1903.07392 March 2019.

    • Altuntac, E. Variational Regularization Strategy for Atmospheric Tomography
      Institute for Numerical and Applied Mathematics, University of Goettingen, July 2016.

    • Altuntac, E. Generalized Variational Source Condition Associated with the Bregman Distance-I: Verification of the Variational Source Condition and Stability of the Total Error Estimation.
      https://arxiv.org/abs/1606.03650 . July 2016.

    • Altuntac, E. Quasi-Newton Approach for an Atmospheric Tomography Problem.
      https://arxiv.org/abs/1511.08022 April 2016.

    • Altuntac E. On convergence of an alternating method for a Cauchy problem for the Helmholtz equation.
      https://www.impan.pl/wydawnictwa/preprints_impan/p730.pdf IMPAN preprint 730, June 2011.

    Numerical Instruments

    During my doctoral studies, I have developed a special interest in coding up and implementation of some numerical tools that have been beneficial to my research. Addition to the list below, I have also performed some test implementations for the software SAMSARA developed by D. R. Luke.

    Conferences/Workshops/Summer Schools

    • AIP-2019 - Applied Inverse Problems Conference July, 08th - 12th, 2019, Grenoble - France (talk)
    • Finnish Inverse Problems Summer School 2019 - June, 3 - 7, 2019, Helsinki, Finland
    • FNRS Contact Group "Wavelets and applications", November 7, 2018, Universite Libre de Bruxelles, Brussels - Belgium (talk)
    • IFIP TC 7-Conference on System Modelling and Optimization, July 23-27, 2018, Essen - Germany (talk)
    • Inverse Problems in Wave Propagation - IWaP-2015, April 7-10, 2015. University of Bremen, Bremen/Germany. (poster presentation)
    • Recent Progress in Mathematical and Numerical Analysis of Inverse Problems, May 19-23, 2014. CIRM, Marseille/France. (poster presentation)
    • Inverse Problems: IP-TA 2010, Developments in Theory and Application, February 9-12, 2010. Institute of Mathematics of The Polish Academy of Sciences, Warsaw/Poland.


    • September 2019 - present; Research Scientist, Cognitive Radar, Fraunhofer FHR, Bonn / Germany.
    • October 2017 - September 2019t; Post-Doctoral Researcher, Department of Mathematics, Université libre de Bruxelles, Brussels / Belgium.
    • August 2016 - August 2017 (resigned); Research scientist, Microflown Avisa, Arnhem/Netherlands.
    • September 2015 - January 2016; Research assistant, Institute for Numerical and Applied Mathematics, University of Göttingen. Göttingen/Germany.
    • March 2015 - August 2015; Research assistant, Institute of Mathematics, University of Göttingen. Göttingen/Germany.
    • February 2012 - February 2015; Research scientist, German Federal Weather Service, Research and Development, Data Assimilation Unit, Offenbach am Main/Germany.
    • September 2009 - September 2010; Research assistant, Institute of Mathematics of The Polish Academy of Sciences, Numerical Analysis Laboratory, Warsaw/Poland.


    • Computer Skills/Experiences: MATLAB, Linux Ubuntu/openSUSE, Mac OS.
    • Hobbies: Chess, The game of GO, Aikido (3rd Kyu by the Aikido dojo Frankfurt), Brazilian Jiu-Jitsu (2nd degree white belt by ICON BJJ Brussels)