I am currently analyzing EEG data using Brainstorm and have a question regarding sensor visualization.
In my workflow, EEG channel locations are co-registered with each participant’s structural MRI based on head points measured with a 3D scanner. When I check the sensor positions using the 3D sensor cap, the layout appears normal. However, when I display the 2D sensor cap, the sensor layout appears distorted and looks elliptical.
Could you please let me know what might be causing this issue?
This is because the 2D sensor cap, uses Lambert azimultal equal-area projection for 2D projection of 3D sensor locations. In this projection the border of the head corresponds to the plane described by LPA, RPA and NAS (i.e., plane Z=0).
Check the visualization notes in the News for September 2025:
https://neuroimage.usc.edu/brainstorm/News#September_2025
If you want to visualize the border electrodes in the head boder of the 2D figure, you can use the 2D disk visualization. Please note that the 2D disk visualization could be misleading in cases where the border electrodes are not around the head.
