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Mark3D - A semi-automated open-source toolbox for 3D head- surface reconstruction and electrode position registration
Suranjita Ganguly1, Malaaika Mihir Chhaya1, Ankita Jain2
1Department of Biomedical Engineering, Indian Institute of Technology, Hyderabad, India.
Medical & Biological Engineering & Computing
|November 7, 2024
Summary
Mark3D reconstructs 3D head surfaces using phone videos for accurate electroencephalography (EEG) sensor localization. This open-source tool offers a cost-effective and user-friendly alternative to expensive 3D scanners, achieving high precision for source localization.
Area of Science:
- Neuroscience
- Biomedical Engineering
- Medical Imaging
Background:
- Accurate electroencephalography (EEG) source localization requires precise co-registration of sensor locations with subject MRIs.
- Current methods like electromagnetic tracking and 3D scanning have limitations, including cost, speed, and immobility.
- Photogrammetry presents a cost-effective alternative but demands extensive sampling and robust post-processing tools.
Purpose of the Study:
- To introduce Mark3D, an open-source tool for 3D head-surface reconstruction from phone camera video.
- To provide a user-friendly interface for electrode localization and tracking, integrating with existing neuroimaging toolboxes.
- To establish a cost-effective and efficient method for EEG sensor localization, overcoming limitations of current technologies.
Main Methods:
- Developed Mark3D, an integrated tool utilizing video-based photogrammetry for 3D head-surface reconstruction.
- Incorporated blur detection algorithms and a dedicated UI for user-friendly electrode placement and tracking.
- Benchmarked accuracy against a commercial 3D scanner, using reconstructed surfaces for pseudo-specific MRI template creation and source reconstruction.
Main Results:
- Achieved mean EEG electrode positional errors of 0.09 ± 0.01 mm compared to ground truth 3D scans.
- Source reconstruction errors were minimal: 0.033 ± 0.016 mm (left hemisphere) and 0.037 ± 0.017 mm (right hemisphere).
- Temporal and occipital areas showed slightly higher, yet acceptable, positional errors compared to other cortical regions.
Conclusions:
- Mark3D offers a highly accurate and cost-effective solution for 3D head-surface reconstruction and EEG sensor localization.
- The tool simplifies the process, eliminating the need for expensive equipment and complex spatial sampling.
- Mark3D facilitates improved multi-modal measurements and EEG source analysis through its integration capabilities and user-friendly design.

