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Dr. Stefan Zellmann


  • Tel.: +49 (0) 221 470 89615
  • Mail: lastname at uni-koeln.de

Research Interests:

  • Direct volume rendering
  • Physically based and photorealistic rendering
  • High performance computing
  • GPGPU computing
  • FPGA programming


  • Vorlesung Praktische Informatik (SS 2019): Architektur und Programmierung von Grafik- und Koprozessoren [Link]
  • Hauptseminar Nutzung von Grafikprozessoren zur Darstellung und Simulation [Link]
  • Vorlesung Technische Informatik (SS 2018): Architektur und Programmierung von Grafik- und Koprozessoren [Link]


  • Visionaray ray tracing framework [Link]
  • Virvo volume rendering library [Link]
  • HPSC TerrSys: High performance computing in terrestrial systems [Link]

Twitter Account:


Orcid ID:


Peer-Reviewed Publications:

  • S. Zellmann, D. Meurer, U. Lang (2019),
    "Hybrid Grids for Sparse Volume Rendering".
    IEEE Visualization, Vancouver, Canada, October 20-25, 2019.
    Details Link PDF
  • S. Zellmann, J.P. Schulze, U. Lang (2019),
    "Binned k-d Tree Construction for Sparse Volume Data on Multi-Core and GPU Systems".
    IEEE Transactions on Visualization and Computer Graphics (TVCG), Early Access.
  • S. Zellmann, M. Hellmann, U. Lang (2019),
    "A Linear Time BVH Construction Algorithm for Sparse Volumes".
    IEEE Pacific Visualization Symposium (PacificVis 2019), Bangkok, Thailand, April 23-26, 2019.
    Details Link PDF
  • S. Zellmann, J.P. Schulze, U. Lang (2018),
    "Rapid k-d Tree Construction for Sparse Volume Data".
    Eurographics Symposium on Parallel Graphics and Visualization (EGPGV 2018), Brno, Czech Republic, June 4, 2018.
    Details Link Bibtex Slides
  • S. Zellmann, U. Lang (2017),
    "C++ Compile Time Polymorphism for Ray Tracing".
    Proceedings of the 22nd Symposium on Vision, Modelling and Visualization (VMV 2017), Bonn, Germany, September 25-27, 2017.
    Details Link PDF Bibtex
  • S. Zellmann, D. Wickeroth, U. Lang (2017),
    "Visionaray: A Cross-Platform Ray Tracing Template Library".
    Proceedings of the 10th Workshop on Software Engineering and Architectures for Realtime Interactive Systems (IEEE SEARIS 2017), Los Angeles, California, USA, March 19, 2017.
    Details PDF Slides
  • S. Zellmann, M. Hoevels, U. Lang (2017),
    "Ray traced volume clipping using multi-hit BVH traversal".
    Proceedings of Visualization and Data Analysis (VDA), Burlingame, California, USA, January 29-February 2, 2017. DOI: 10.2352/ISSN.2470-1173.2017.1.VDA-392
    Details Link PDF Bibtex Slides
  • D. Hoffmeister, S. Zellmann, A. Pastoors, M. Kehl, P. Cantalejo, J. Ramos, G. C. Weniger, G. Bareth (2015),
    "The investigation of the Ardales Cave, Spain - 3D documentation, topographic analyses, and lighting simulations based on terrestrial laser scanning".
    Archaeological Prospection. DOI: 10.1002/arp.1519
    Link Bibtex
  • S. Zellmann, Y. Percan, U. Lang (2015),
    "Advanced texture filtering: a versatile framework for reconstructing multi-dimensional image data on heterogeneous architectures".
    Proceedings of Visualization and Data Analysis (VDA), San Francisco, California, USA, February 8-12, 2015.
    Link Bibtex
  • Y. Percan, S. Zellmann, U. Lang (2014),
    "Asymptotic error of cubic B-spline interpolation using prefiltering".
    Springer Numerical Algorithms. DOI: 10.1007/s11075-014-9941-x
    Link PDF Bibtex
  • D. Hoffmeister, S. Zellmann, K. Kindermann, A. Pastoors, U. Lang, O. Bubenzer, G. C. Weniger, G. Bareth (2014),
    "Geoarchaeological site documentation and analysis of 3D data derived by terrestrial laser scanning".
    ISPRS Annals of Photogrammetry, Remote Sensing and Spatial Information Sciences, II-5, pp. 173-179, 2014.
    Link Bibtex
  • S. Zellmann, U. Lang (2013),
    "A Comparison of GPU Box-Plane Intersection Algorithms for Direct Volume Rendering".
    Proceedings of the 14th IASTED International Conference on Computer Graphics and Imaging (CGIM),
    Innsbruck, Austria, February 12-14, 2013.
    Link PDF Bibtex Slides
  • S. Zellmann, U. Lang (2012),
    "A Software Architecture for Distributed Volume Rendering on HPC Systems".
    Proceedings of the 24th IASTED International Conference on Parallel and Distributed Computing and Systems (PDCS),
    Las Vegas, Nevada, USA, November 12-14, 2012.
    Link Bibtex
  • S. Zellmann, M. Aumüller, U. Lang (2012),
    "Image-Based Remote Real-Time Volume Rendering - Decoupling Rendering from View Point Updates".
    Proceedings of the ASME 2012 International Design Engineering Technical Conferences & Computers and Information in Engineering Conference (IDETC/CIE),
    Chicago, Illinois, USA, August 12-15, 2012.
    Link Bibtex

Technical Reports:

  • S. Zellmann (2019)
    "Adding Custom Intersectors to the C++ Ray Tracing Template Library Visionaray".
  • S. Zellmann (2019),
    "Comparing Hierarchical Data Structures for Sparse Volume Rendering with Empty Space Skipping".


  • S. Zellmann (2014),
    "Interactive High-Performance Volume Rendering".
    PhD thesis, 19 August 2014.
    Link Bibtex


  • S. Zellmann (2016), "Visionaray: A Modern C++ Framework for Prototyping Ray Tracing Kernels". Libre Graphics Meeting 2016, London, United Kingdom, April 15-18, 2016.
    Link Slides