Event-based imaging

At the Institute of Thermo- and Fluid Dynamics at TU Ilmenau, we develop advanced optical measurement techniques to better understand turbulent flows. Conventional methods such as frame-based PIV and optical flow provide valuable insights, but their spatial and temporal resolution is fundamentally limited. Our research focuses on particle tracking velocimetry (PTV), which enables highly resolved measurements even in strongly turbulent flows and near-wall regions. We also develop time-resolved multi-frame tracking to capture not only velocity, but also acceleration and higher-order flow dynamics. A particularly promising direction is event-based particle tracking velocimetry (EB-PTV), which has the potential to overcome the limits of frame-based imaging and open new pathways for turbulence analysis and control.

In this respect, we developed the STELLA toolbox, which allows users to compose their own data processing pipelines ranging from dense representations in the form of pseudo-frames to sparse evaluations based on event streams. Feel free to use the toolbox for your own projects or contact Christian Cierpka (christian.cierpka@tu-ilmenau.de) for collaborations.

Schematic representation of possible processing pipelines using either a dense representation (conventional) or direct processing of events. The background indicates data volume from frame-based representations (high→dark) to Lagrangian particle trajectories (low→white) (adopted from Sachs et al. 2026).
Measurement of particle trajectories in the viscous sub-layer at the and Re_τ ≈ 5000 at Centre for International Cooperation in Long Pipe Experiments (CICLoPE) of University of Bologna
Possible applications areas:
  • Lagrangian turbulence research
  • Microfluidics
  • Object-aware structure reconstruction and particle tracking velocimetry
  • Low energy flow characterization
Recent publications 

S. Sachs, S. Jung, M. Kahl, M. Keuper, C. Willert, C. Cierpka (2026) STELLA: A modular framework for Spatio-Temporal Event-based Lagrangian particLe trAcking, Experiments in Fluids 67, 110, DOI: 10.1007/s00348-026-04253-8, open access

S. Sachs, J. Heiland, C. Willert, M. Rossi, C. Cierpka: Event-based Lagrangian Particle Tracking for turbulent shear flows, 14th Int. Symposium on Turbulence and Shear Flow Phenomena (TSFP 14), 28.-31.07.2026, Heidelberg, Germany (https://elib.dlr.de/226295/1/254.pdf)

C. Willert, S. Sachs, D. Schanz, C. Cierpka, G. Bellani: Event-based 3D-Lagrangian Particle Tracking using Different Processing Strategies, 22nd International Symposium on Applications of Laser Techniques to Fluid Mechanics, 29.06.-02.07.2026, Lisbon, Portugal (https://elib.dlr.de/225147/1/Lisbon2026_EventBasedSTB_Paper201.pdf) 

Toolbox

GitHub - sesa1504/STELLA: STELLA - a modular framework for statiotemporal event-based Lagrangian particle tracking · GitHub

Collaboration Partners

Prof. Margret Keuper (Chair for Machine Learning, University of Mannheim)

Dr. Christian Willert (Institute of Propulsion Technology, German Aerospace Center (DLR), Cologne)

Prof. Massimiliano Rossi and Prof. Gebriele Bellani (Department of Industrial Engineering / CIRI Aerospace, University of Bologna, Forlì, Italy)