[FieldTrip] BrainProducts Easycap layout

"Jörn M. Horschig" jm.horschig at donders.ru.nl
Wed Jan 22 15:55:21 CET 2014

Hi Hweeling,

have you checked FieldTrip/template/layout? There are a bunch of easycap 
layout already available. Otherwise, you can easily transform your 
coordinates to the x/y/z plane, you just need to estimate the size of 
the head. This is what is happening inside ft_read_sens:

       % it contains theta and phi
       sens.label   = cellfun(@str2double, tmp{1}(2:end));
       theta = cellfun(@str2double, tmp{2}(2:end));
       phi   = cellfun(@str2double, tmp{3}(2:end));
       radians = @(x) pi*x/180;
       warning('assuming a head radius of 85 mm');
       x = 85*cos(radians(phi)).*sin(radians(theta));
       y = 85*sin(radians(theta)).*sin(radians(phi));
       z = 85*cos(radians(theta));
       sens.unit = 'cm';
       sens.elecpos = [x y z];
       sens.chanpos = [x y z];

Then you can project to a 2D plane, there are a number of methods 
available in Matlab for that.


On 1/22/2014 3:41 PM, Hwee Ling Lee wrote:
> Dear all,
> I would like to know if anyone has the layout for 128 EEG channels for 
> BrainProduct easycap.
> I have the information of the theta/phi coordinates for each of the 
> channels, but I'm not sure how to use these values to create the 
> layout in fieldtrip.
> It'll be great if someone can help me on this!
> Thanks.
> Best regards,
> Hweeling
> _______________________________________________
> fieldtrip mailing list
> fieldtrip at donders.ru.nl
> http://mailman.science.ru.nl/mailman/listinfo/fieldtrip

Jörn M. Horschig
PhD Student
Donders Institute for Brain, Cognition and Behaviour
Centre for Cognitive Neuroimaging
Radboud University Nijmegen
Neuronal Oscillations Group
FieldTrip Development Team

P.O. Box 9101
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E-Mail: jm.horschig at donders.ru.nl
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