Deymed TruScan montage file (.ced file)

Hi guys, firstly, thanks again for mne which allowed me to successfully finish my PhD 🥇🎉

My new workplace has a 128 channels TruScan Deymed system, from which I’ve been trying to get usable data.

However, the montage is not supported natively by mne. The customer service sent me a .txt file (deymed_layout_128.txt), in which there are columns related to channel names, Phi, Theta, and x y z coordinates (attached). They also sent a .ced file, which contains the same info, which I cannot attach (but can send it via email).

Unfortunately, using the mne.channels.read_montage("deymed_layout_128", path = ".") doesn’t work:

mne.channels.read_montage("deymed_layout_128", path = ".")
Traceback (most recent call last):

  File "<ipython-input-22-265da416e197>", line 1, in <module>
    mne.channels.read_montage("deymed_layout_128", path = ".")

  File "C:\Users\Dom\Desktop\WPy-3710\python-3.7.1.amd64\lib\site-packages\mne\channels\montage.py", line 281, in read_montage
    pol = np.deg2rad(data[:, 1].astype(float))

ValueError: could not convert string to float: 'Fp1'

How can I read this montage? Thanks again!

[agramfort]

May I know if these fiducial points are information that I can obtain from the vendor (i.e., fixed values for the cap) or is it something acquired for each individual subject using, for instance, their MRI?

you can get it from template. You can also infer it from where the ears are on the cap.

see for example https://mne.tools/stable/auto_tutorials/source-modeling/plot_eeg_no_mri.html to see how it should look like on fsaverage.

And out of curiosity, why is the coordinates array specified as yxz (I would have expected xyz)?

it’s the convention of the head coord system in MNE. See: https://mne.tools/dev/auto_tutorials/source-modeling/plot_source_alignment.html#coordinate-frame-definitions

[DominiqueMakowski]

@agramfort Thanks!

May I know if these fiducial points are information that I can obtain from the vendor (i.e., fixed values for the cap) or is it something acquired for each individual subject using, for instance, their MRI?

And out of curiosity, why is the coordinates array specified as yxz (I would have expected xyz)?