[FieldTrip] Electrode location structure

Stolk, A. a.stolk at fcdonders.ru.nl
Mon Jan 14 21:47:26 CET 2013

Dear Emma, FieldTrip is moving towards layouts that are based on an image  (for reference) and that are stored in a .mat file . For some examples, see: http://fieldtrip.fcdonders.nl/template/layout The layout structure stored in those .mat files contains fields that describe the position (.pos), the width (.width), and the height (.height), and the naming (.label) of the electrodes. Furthermore, it contains fields that describe the topographic interpolation boundaries (.mask) and the outlines of the 'head' (.outline). Previous, and still supported, layout files (with a  .lay extension) typically contain a data matrix consisting of 5 columns. The first two columns describe the position of each electrode whereas the third, fourth, and fifth column describe the width, height, and label (i.e. number/name) for each electrode respectively. If you have a bitmap image, I'd recommend to create a layout variable and to store it in a .mat file. Try using  the following commands:   cfg.img = '*.bmp'  lay = ft_prepare_layout(cfg, []) Yours, Arjen ----- Oorspronkelijk bericht -----
> Van: "Emma Holmes" <eh776 at york.ac.uk>
> Aan: fieldtrip at science.ru.nl
> Verzonden: Maandag 14 januari 2013 21:14:23
> Onderwerp: [FieldTrip] Electrode location structure
> Dear FieldTrip users,
> I would like to define the positions of the EEG electrodes myself.
> I have a structure containing the x,y,z co-ordinates and channel names
> for 66 channels. However, I am having trouble converting this to a
> FieldTrip structure.
> I’m trying to use the ft_prepare_layout() function.
> Can anyone tell me what format the input structure should be in? i.e.
> what fields it should contain.
> Here, I’m referring to the part of the documentation ‘cfg.elec: 
> structure with electrode positions’, but can’t seem to find any
> explanation of what the layout of this structure should be.
> Many thanks,
> Emma
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