Lukas Schach, M.Sc.

Lukas Schach, M. Sc.

Wissenschaftlicher Mitarbeiter/PhD Student

lukas.schach@uni-wuerzburg.de

Psychologie Intelligenter Interaktiver Systeme
Julius-Maximilians-Universität Würzburg
Institut für Mensch-Computer-Medien
Universität Würzburg
Emil-Fischer-Straße 50
97074 Würzburg
Deutschland

About me

Lukas completed his bachelor’s degree in Aerospace Informatics in Würzburg, and later completed his master’s degree in Computer Science at the University of Würzburg.

Lukas has been working as a research assistant since August 2023. His research focuses on the use of behavioural biometrics to identify and authenticate people in VR contexts.

Publications

2024[ to top ]

Rack, Christian, Lukas Schach, Felix Achter, Yousof Shehada, Jinghuai Lin, and Marc Erich Latoschik. “Motion Passwords”. In Proceedings of the 30th ACM Symposium on Virtual Reality Software and Technology, 1-11. VRST ’24. New York, NY, USA: Association for Computing Machinery, 2024. https://doi.org/10.1145/3641825.3687711.
- [ Abstract ]
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This paper introduces “Motion Passwords”, a novel biometric authentication approach where virtual reality users verify their identity by physically writing a chosen word in the air with their hand controller. This method allows combining three layers of verification: knowledge-based password input, handwriting style analysis, and motion profile recognition. As a first step towards realizing this potential, we focus on verifying users based on their motion profiles. We conducted a data collection study with 48 participants, who performed over 3800 Motion Password signatures across two sessions. We assessed the effectiveness of feature-distance and similarity-learning methods for motion-based verification using the Motion Passwords as well as specific and uniform ball-throwing signatures used in previous works. In our results, the similarity-learning model was able to verify users with the same accuracy for both signature types. This demonstrates that Motion Passwords, even when applying only the motion-based verification layer, achieve reliability comparable to previous methods. This highlights the potential for Motion Passwords to become even more reliable with the addition of knowledge-based and handwriting style verification layers. Furthermore, we present a proof-of-concept Unity application demonstrating the registration and verification process with our pretrained similarity-learning model. We publish our code, the Motion Password dataset, the pretrained model, and our Unity prototype on https://github.com/cschell/MoPs

@conference{rack2024motion, abstract = {This paper introduces “Motion Passwords”, a novel biometric authentication approach where virtual reality users verify their identity by physically writing a chosen word in the air with their hand controller. This method allows combining three layers of verification: knowledge-based password input, handwriting style analysis, and motion profile recognition. As a first step towards realizing this potential, we focus on verifying users based on their motion profiles. We conducted a data collection study with 48 participants, who performed over 3800 Motion Password signatures across two sessions. We assessed the effectiveness of feature-distance and similarity-learning methods for motion-based verification using the Motion Passwords as well as specific and uniform ball-throwing signatures used in previous works. In our results, the similarity-learning model was able to verify users with the same accuracy for both signature types. This demonstrates that Motion Passwords, even when applying only the motion-based verification layer, achieve reliability comparable to previous methods. This highlights the potential for Motion Passwords to become even more reliable with the addition of knowledge-based and handwriting style verification layers. Furthermore, we present a proof-of-concept Unity application demonstrating the registration and verification process with our pretrained similarity-learning model. We publish our code, the Motion Password dataset, the pretrained model, and our Unity prototype on https://github.com/cschell/MoPs}, address = {New York, NY, USA}, author = {Rack, Christian and Schach, Lukas and Achter, Felix and Shehada, Yousof and Lin, Jinghuai and Latoschik, Marc Erich}, booktitle = {Proceedings of the 30th ACM Symposium on Virtual Reality Software and Technology}, keywords = {schell}, number = 19, pages = {1-11}, publisher = {Association for Computing Machinery}, series = {VRST '24}, title = {Motion Passwords}, year = 2024 }
Rack, Christian, Vivek Nair, Lukas Schach, Felix Foschum, Marcel Roth, and Marc Erich Latoschik. “Navigating the Kinematic Maze: Analyzing, Standardizing and Unifying XR Motion Datasets”. In 2024 IEEE Conference on Virtual Reality and 3D User Interfaces Abstracts and Workshops (VRW). IEEE, 2024. https://doi.org/10.1109/VRW62533.2024.00098.
- [ Abstract ]
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This paper addresses the critical importance of standards and documentation in kinematic research, particularly within Extended Reality (XR) environments. We focus on the pivotal role of motion data, emphasizing the challenges posed by the current lack of standardized practices in XR user motion datasets. Our work involves a detailed analysis of 8 existing datasets, identifying gaps in documentation and essential specifications such as coordinate systems, rotation representations, and units of measurement. We highlight how these gaps can lead to misinterpretations and irreproducible results. Based on our findings, we propose a set of guidelines and best practices for creating and documenting motion datasets, aiming to improve their quality, usability, and reproducibility. We also created a web-based tool for visual inspection of motion recordings, further aiding in dataset evaluation and standardization. Furthermore, we introduce the XR Motion Dataset Catalogue, a collection of the analyzed datasets in a unified and aligned format. This initiative significantly streamlines access for researchers, allowing them to download partial or entire datasets with a single line of code and without the need for additional alignment efforts. Our contributions enhance dataset integrity and reliability in kinematic research, paving the way for more consistent and scientifically robust studies in this evolving field.

@inproceedings{noauthororeditor2024navigating, abstract = {This paper addresses the critical importance of standards and documentation in kinematic research, particularly within Extended Reality (XR) environments. We focus on the pivotal role of motion data, emphasizing the challenges posed by the current lack of standardized practices in XR user motion datasets. Our work involves a detailed analysis of 8 existing datasets, identifying gaps in documentation and essential specifications such as coordinate systems, rotation representations, and units of measurement. We highlight how these gaps can lead to misinterpretations and irreproducible results. Based on our findings, we propose a set of guidelines and best practices for creating and documenting motion datasets, aiming to improve their quality, usability, and reproducibility. We also created a web-based tool for visual inspection of motion recordings, further aiding in dataset evaluation and standardization. Furthermore, we introduce the XR Motion Dataset Catalogue, a collection of the analyzed datasets in a unified and aligned format. This initiative significantly streamlines access for researchers, allowing them to download partial or entire datasets with a single line of code and without the need for additional alignment efforts. Our contributions enhance dataset integrity and reliability in kinematic research, paving the way for more consistent and scientifically robust studies in this evolving field.}, author = {Rack, Christian and Nair, Vivek and Schach, Lukas and Foschum, Felix and Roth, Marcel and Latoschik, Marc Erich}, booktitle = {2024 IEEE Conference on Virtual Reality and 3D User Interfaces Abstracts and Workshops (VRW)}, keywords = {schell}, organization = {IEEE}, title = {Navigating the Kinematic Maze: Analyzing, Standardizing and Unifying XR Motion Datasets}, year = 2024 }

2023[ to top ]

Rack, Christian, Lukas Schach, and Marc Latoschik. “Motion Learning Toolbox – A Python Library for Preprocessing of XR Motion Tracking Data for Machine Learning Applications”. https://github.com/cschell/Motion-Learning-Toolbox.
- [ Abstract ]
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The Motion Learning Toolbox is a Python library designed to facilitate the preprocessing of motion tracking data in extended reality (XR) setups. It's particularly useful for researchers and engineers wanting to use XR tracking data as input for machine learning models. Originally developed for academic research targeting the identification of XR users by their motions, this toolbox includes a variety of data encoding methods that enhance machine learning model performance.

@misc{rack2023motionlearningtoolbox, abstract = {The Motion Learning Toolbox is a Python library designed to facilitate the preprocessing of motion tracking data in extended reality (XR) setups. It's particularly useful for researchers and engineers wanting to use XR tracking data as input for machine learning models. Originally developed for academic research targeting the identification of XR users by their motions, this toolbox includes a variety of data encoding methods that enhance machine learning model performance.}, author = {Rack, Christian and Schach, Lukas and Latoschik, Marc}, howpublished = {GitHub Repository}, keywords = {schell}, title = {Motion Learning Toolbox – A Python library for preprocessing of XR motion tracking data for machine learning applications}, year = 2023 }

2022[ to top ]

Rack, Christian, Fabian Sieper, Lukas Schach, Murat Yalcin, and Marc E. Latoschik. “Dataset: Who Is Alyx? (GitHub Repository)”. https://doi.org/10.5281/zenodo.6472417.
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This dataset contains over 110 hours of motion, eye-tracking and physiological data from 71 players of the virtual reality game “Half-Life: Alyx”. Each player played the game on two separate days for about 45 minutes using a HTC Vive Pro.

@dataset{who_is_alyx_2022, abstract = {This dataset contains over 110 hours of motion, eye-tracking and physiological data from 71 players of the virtual reality game “Half-Life: Alyx”. Each player played the game on two separate days for about 45 minutes using a HTC Vive Pro.}, author = {Rack, Christian and Sieper, Fabian and Schach, Lukas and Yalcin, Murat and Latoschik, Marc E.}, keywords = {VirtualReality}, month = {04}, title = {Dataset: Who is Alyx? (GitHub Repository)}, year = 2022 }

Hubland Nord, Gebäude 50

Wissenschaftlicher Mitarbeiter/PhD Student

Picture credits