[Eeglablist] Coordinate systems question

Arnaud Delorme arno at salk.edu
Thu Feb 17 20:50:43 PST 2005


Dear Lazlo,

it is true that different formats use different axes (and even different 
orientations in the polar space). However, the origin should be the 
same. I would not use the EEGLAB sample location file as a reference (I 
have looked at it and it is true that it does not seem to contain 
standard electrode locations - I will try to think of fixing that later 
since I am at a conference right now). On the other hand, when EEGLAB 
looks up automatically channel locations (if you only use channel 
labels), it uses the standard BESA standard locations (see the folder 
sample_loc folder).

>understand correctly, the system should not influence the localisation, until it is 
>coregistered with te fiducial points (LE,RE, Nasion), since the head model is getting 
>transformed to the MRI head using the coordinates of the fiducials .
>  
>
This is correct (if you use standard electrode locations).

Best,

Arno




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