channel locations

[peng wang]

Thank you, Vladimir.
Does that mean I can get the coil position by the equation below; and ignore the "ori" information?
position = data.grad.tra*data.grad. pnt;

Best
Peng
=========
Dear Peng,

These are the real locations. Each channel in your MEG data is
computed by combining signals from several magnetometer coils (usually
two). The locations of these coils are given in grad.pnt and the way
they are combined is described by grad.tra.

Best,

Vladimir

On Tue, Jun 23, 2009 at 8:03 PM, peng wang<prion.w at gmail.com> wrote:
> Dear list members,
>
>        I am a new user of fieldtrip. I have some data preprocessed by fieldtrip. I want to find the channel location information from the field 'grad' in the dataset after this procedure. The original channel number should be 303, but in this field , it looks like this:
>          pnt:  [597*3];
>          ori:  [597*3];
>          tra:  [303*597];
>        label:  {303*1 cell}
>         unit:  'cm'
>  balance:  {1*1 struct}
>
> It seemed there were some transformations(303->597). How did this happen? How can I retrieve the real location information of the sensors?Thank you very much for help!
>
> peng
>
> ----------------------------------
> The aim of this list is to facilitate the discussion between users of the FieldTrip  toolbox, to share experiences and to discuss new ideas for MEG and EEG analysis. See also http://listserv.surfnet.nl/archives/fieldtrip.html and http://www.ru.nl/neuroimaging/fieldtrip.
>
>

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The aim of this list is to facilitate the discussion between users of the FieldTrip  toolbox, to share experiences and to discuss new ideas for MEG and EEG analysis. See also http://listserv.surfnet.nl/archives/fieldtrip.html and http://www.ru.nl/neuroimaging/fieldtrip.