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Marcel Krüger, M.Sc.
Room K106
Phone: +49 241 80 24966
Fax: +49 241 80 22134
Email: krueger@vis.rwth-aachen.de

Visualization Team



Publications


A Case Study on Providing Accessibility-Focused In-Transit Architectures for Neural Network Simulation and Analysis


Marcel Krüger, Simon Oehrl, Torsten Wolfgang Kuhlen, Tim Gerrits
ISC High Performance 2023

Due to the ever-increasing availability of high-performance computing infrastructure, developers can simulate increasingly complex models. However, the increased complexity comes with new challenges regarding data processing and visualization due to the sheer size of simulations. Exploring simulation results needs to be handled efficiently via in-situ/in-transit analysis during run-time. However, most existing in-transit solutions require sophisticated and prior knowledge and significant alteration to existing simulation and visualization code, which produces a high entry barrier for many projects. In this work, we report how Insite, a lightweight in-transit pipeline, provided in-transit visualization and computation capability to various research applications in the neuronal network simulation domain. We describe the development process, including feedback from developers and domain experts, and discuss implications.

» Show BibTeX

@inproceedings{kruger2023case,

title={A Case Study on Providing Accessibility-Focused In-Transit Architectures for Neural Network Simulation and Analysis},
author={Kr{\"u}ger, Marcel and Oehrl, Simon and Kuhlen, Torsten Wolfgang and Gerrits, Tim},
booktitle={International Conference on High Performance Computing},
pages={277--287},
year={2023},
organization={Springer}
}





A Case Study on Providing Immersive Visualization for Neuronal Network Data Using COTS Soft- and Hardware


Marcel Krüger, Qin Li, Torsten Wolfgang Kuhlen, Tim Gerrits
2023 IEEE Conference on Virtual Reality and 3D User Interfaces Abstracts and Workshops (VRW)
pubimg

COTS VR hardware and modern game engines create the impression that bringing even complex data into VR has become easy. In this work, we investigate to what extent game engines can support the development of immersive visualization software with a case study. We discuss how the engine can support the development and where it falls short, e.g., failing to provide acceptable rendering performance for medium and large-sized data sets without using more sophisticated features.

» Show BibTeX

@INPROCEEDINGS{10108843,
author={Krüger, Marcel and Li, Qin and Kuhlen, Torsten W. and Gerrits, Tim},
booktitle={2023 IEEE Conference on Virtual Reality and 3D User Interfaces Abstracts and Workshops (VRW)},
title={A Case Study on Providing Immersive Visualization for Neuronal Network Data Using COTS Soft- and Hardware},
year={2023},
volume={},
number={},
pages={201-205},
doi={10.1109/VRW58643.2023.00050}}





Poster: Insite Pipeline - A Pipeline Enabling In-Transit Processing for Arbor, NEST and TVB


Marcel Krüger, Tim Gerrits, Torsten Wolfgang Kuhlen, Benjamin Weyers
HBP Summit 2023
pubimg

Simulation of neuronal networks has steadily advanced and now allows for larger and more complex models. However, scaling simulations to such sizes comes with issues and challenges.Especially the amount of data produced, as well as the runtime of the simulation, can be limiting.Often, storing all data on disk is impossible, and users might have to wait for a long time until they can process the data.A standard solution in simulation science is to use in-transit approaches.In-transit implementations allow users to access data while the simulation is still running and do parallel processing outside the simulation.This allows for early insights into the results, early stopping of simulations that are not promising, or even steering of the simulations.Existing in-transit solutions, however, are often complex to integrate into the workflow as they rely on integration into simulators and often use data formats that are complex to handle.This is especially constraining in the context of multi-disciplinary research conducted in the HBP, as such an important feature should be accessible to all users.

To remedy this, we developed Insite, a pipeline that allows easy in-transit access to simulation data of multiscale simulations conducted with TVB, NEST, and Arbor.

» Show BibTeX

@misc{kruger_marcel_2023_7849225,
author = {Krüger, Marcel and
Gerrits, Tim and
Kuhlen, Torsten and
Weyers, Benjamin},
title = {{Insite Pipeline - A Pipeline Enabling In-Transit
Processing for Arbor, NEST and TVB}},
month = mar,
year = 2023,
publisher = {Zenodo},
doi = {10.5281/zenodo.7849225},
url = {https://doi.org/10.5281/zenodo.7849225}
}





Insite: A Pipeline Enabling In-Transit Visualization and Analysis for Neuronal Network Simulations


Marcel Krüger, Simon Oehrl, Ali Can Demiralp, Sebastian Spreizer, Jens Bruchertseifer, Torsten Wolfgang Kuhlen, Tim Gerrits, Benjamin Weyers
ISC High Performance 2022
pubimg

Neuronal network simulators are central to computational neuroscience, enabling the study of the nervous system through in-silico experiments. Through the utilization of high-performance computing resources, these simulators are capable of simulating increasingly complex and large networks of neurons today. Yet, the increased capabilities introduce a challenge to the analysis and visualization of the simulation results. In this work, we propose a pipeline for in-transit analysis and visualization of data produced by neuronal network simulators. The pipeline is able to couple with simulators, enabling querying, filtering, and merging data from multiple simulation instances. Additionally, the architecture allows user-defined plugins that perform analysis tasks in the pipeline. The pipeline applies traditional REST API paradigms and utilizes data formats such as JSON to provide easy access to the generated data for visualization and further processing. We present and assess the proposed architecture in the context of neuronal network simulations generated by the NEST simulator.

» Show BibTeX

@InProceedings{10.1007/978-3-031-23220-6_20,
author="Kr{\"u}ger, Marcel and Oehrl, Simon and Demiralp, Ali C. and Spreizer, Sebastian and Bruchertseifer, Jens and Kuhlen, Torsten W. and Gerrits, Tim and Weyers, Benjamin",
editor="Anzt, Hartwig and Bienz, Amanda and Luszczek, Piotr and Baboulin, Marc",
title="Insite: A Pipeline Enabling In-Transit Visualization and Analysis for Neuronal Network Simulations",
booktitle="High Performance Computing. ISC High Performance 2022 International Workshops",
year="2022",
publisher="Springer International Publishing",
address="Cham",
pages="295--305",
isbn="978-3-031-23220-6"
}





Astray: A Performance-Portable Geodesic Ray Tracer


Ali Can Demiralp, Marcel Krüger, Chu Chao, Torsten Wolfgang Kuhlen, Tim Gerrits
VMV 2022: Vision, Modeling, and Visualization
pubimg

Geodesic ray tracing is the numerical method to compute the motion of matter and radiation in spacetime. It enables visualization of the geometry of spacetime and is an important tool to study the gravitational fields in the presence of astrophysical phenomena such as black holes. Although the method is largely established, solving the geodesic equation remains a computationally demanding task. In this work, we present Astray; a high-performance geodesic ray tracing library capable of running on a single or a cluster of computers equipped with compute or graphics processing units. The library is able to visualize any spacetime given its metric tensor and contains optimized implementations of a wide range of spacetimes, including commonly studied ones such as Schwarzschild and Kerr. The performance of the library is evaluated on standard consumer hardware as well as a compute cluster through strong and weak scaling benchmarks. The results indicate that the system is capable of reaching interactive frame rates with increasing use of high-performance computing resources. We further introduce a user interface capable of remote rendering on a cluster for interactive visualization of spacetimes.

» Show BibTeX

@inproceedings {10.2312:vmv.20221208,
booktitle = {Vision, Modeling, and Visualization},
editor = {Bender, Jan and Botsch, Mario and Keim, Daniel A.},
title = {{Astray: A Performance-Portable Geodesic Ray Tracer}},
author = {Demiralp, Ali Can and Krüger, Marcel and Chao, Chu and Kuhlen, Torsten W. and Gerrits, Tim},
year = {2022},
publisher = {The Eurographics Association},
ISBN = {978-3-03868-189-2},
DOI = {10.2312/vmv.20221208}
}





MODE: A modern ordinary differential equation solver for C++ and CUDA


Ali Can Demiralp, Marcel Krüger, Tim Gerrits
ICNAAM 2022: International Conference Of Numerical Analysis And Applied Mathematics

Ordinary differential equations (ODE) are used to describe the evolution of one or more dependent variables using their derivatives with respect to an independent variable. They arise in various branches of natural sciences and engineering. We present a modern, efficient, performance-oriented ODE solving library built in C++20. The library implements a broad range of multi-stage and multi-step methods, which are generated at compile-time from their tableau representations, avoiding runtime overhead. The solvers can be instantiated and iterated on the CPU and the GPU using identical code. This work introduces the prominent features of the library with examples




Poster: A C++20 Interface for MPI 4.0


Ali Can Demiralp, Philipp Mark Martin, Niko Sakic, Marcel Krüger, Tim Gerrits
International Conference for High Performance Computing, Networking, Storage and Analysis
pubimg

We present a modern C++20 interface for MPI 4.0. The interface utilizes recent language features to ease development of MPI applications. An aggregate reflection system enables generation of MPI data types from user-defined classes automatically. Immediate and persistent operations are mapped to futures, which can be chained to describe sequential asynchronous operations and task graphs in a concise way. This work introduces the prominent features of the interface with examples. We further measure its performance overhead with respect to the raw C interface.

» Show BibTeX

@misc{demiralp2023c20,
title={A C++20 Interface for MPI 4.0},
author={Ali Can Demiralp and Philipp Martin and Niko Sakic and Marcel Krüger and Tim Gerrits},
year={2023},
eprint={2306.11840},
archivePrefix={arXiv},
primaryClass={cs.DC}
}





Calibratio - A Small, Low-Cost, Fully Automated Motion-to-Photon Measurement Device


Sebastian Pape, Marcel Krüger, Jan Müller, Torsten Wolfgang Kuhlen
10th Workshop on Software Engineering and Architectures for Realtime Interactive Systems (SEARIS), 2020
pubimg

Since the beginning of the design and implementation of virtual environments, these systems have been built to give the users the best possible experience. One detrimental factor for the user experience was shown to be a high end-to-end latency, here measured as motionto-photon latency, of the system. Thus, a lot of research in the past was focused on the measurement and minimization of this latency in virtual environments. Most existing measurement-techniques require either expensive measurement hardware like an oscilloscope, mechanical components like a pendulum or depend on manual evaluation of samples. This paper proposes a concept of an easy to build, low-cost device consisting of a microcontroller, servo motor and a photo diode to measure the motion-to-photon latency in virtual reality environments fully automatically. It is placed or attached to the system, calibrates itself and is controlled/monitored via a web interface. While the general concept is applicable to a variety of VR technologies, this paper focuses on the context of CAVE-like systems.

» Show Videos
» Show BibTeX

@InProceedings{Pape2020a,
author = {Sebastian Pape and Marcel Kr\"{u}ger and Jan M\"{u}ller and Torsten W. Kuhlen},
title = {{Calibratio - A Small, Low-Cost, Fully Automated Motion-to-Photon Measurement Device}},
booktitle = {10th Workshop on Software Engineering and Architectures for Realtime Interactive Systems (SEARIS)},
year = {2020},
month={March}
}





Talk: Insite: A Generalized Pipeline for In-transit Visualization and Analysis


Simon Oehrl, Jan Müller, Ali Can Demiralp, Marcel Krüger, Sebastian Spreizer, Benjamin Weyers, Torsten Wolfgang Kuhlen
NEST Conference 2020
pubimg

Neuronal network simulators are essential to computational neuroscience, enabling the study of the nervous system through in-silico experiments. Through utilization of high-performance computing resources, these simulators are able to simulate increasingly complex and large networks of neurons today. It also creates new challenges for the analysis and visualization of such simulations. In-situ and in-transport strategies are popular approaches in these scenarios. They enable live monitoring of running simulations and parameter adjustment in the case of erroneous configurations which can save valuable compute resources.

This talk will present the current status of our pipeline for in-transport analysis and visualization of neuronal network simulator data. The pipeline is able to couple with NEST along other simulators with data management (querying, filtering and merging) from multiple simulator instances. Finally, the data is passed to end-user applications for visualization and analysis. The goal is to be integrated into third party tools such as the multi-view visual analysis toolkit ViSimpl.




Passive Haptic Menus for Desk-Based and HMD-Projected Virtual Reality


Daniel Zielasko, Marcel Krüger, Benjamin Weyers, Torsten Wolfgang Kuhlen
IEEE VR Workshop on Everyday Virtual Reality (2019)
pubimg

In this work we evaluate the impact of passive haptic feedback on touch-based menus, given the constraints and possibilities of a seated, desk-based scenario in VR. Therefore, we compare a menu that once is placed on the surface of a desk and once mid-air on a surface in front of the user. The study design is completed by two conditions without passive haptic feedback. In the conducted user study (n = 33) we found effects of passive haptics (present vs- non-present) and menu alignment (desk vs. mid-air) on the task performance and subjective look & feel, however the race between the conditions was close. An overall winner was the mid-air menu with passive haptic feedback, which however raises hardware requirements.

» Show BibTeX

@inproceedings{zielasko2019menu,
title={{Passive Haptic Menus for Desk-Based and HMD-Projected Virtual Reality}},
author={Zielasko, Daniel and Kr{\"u}ger Marcel and Weyers, Benjamin and Kuhlen, Torsten W},
booktitle={Proc. of IEEE VR Workshop on Everyday Virtual Reality},
year={2019}
}





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