[FieldTrip] EGI 64 - channel locations doesn't work in FTrip

[Anna Wieczorek-Taraday]

Hi Robert, 
Thank you for your help. Indeed, the location on the sphere looks good after adjusting these parameters. 
Thank you a lot.
Best regards, 
Anna


Sent from my iPad

> On 12 May 2015, at 11:05, Robert Oostenveld <r.oostenveld at donders.ru.nl> wrote:
> 
> Hi Ana
> 
> The ft_prepare_layout function reads the electrode positions and scales them such that they fit in the sphere that represents the head.
> 
> I suggest you do 
> 
> cfg.layout = ‘yourfilename’
> lay = ft_prepare_layout(cfg);
> 
> cfg = [];
> cfg.layout = lay;
> ft_layoutplot(cfg);
> 
> and then modify lay.pos repeatedly, every time plotting it again, until you are happy with the result. You probably want to  do this for the vertical direction 
> lay.pos(:,2) = (lay.pos(:,2)+shift) .* scale;
> to shift and scale the electrodes to a better fit inside/outside the sphere, and this for the horizontal
> lay.pos(:,1) = lay.pos(:,1) .* scale;
> as they seem to be properly centred along the x-axis alreadly.
> 
> After this, you can 
> save yourlayout.mat lay
> and specify “yourlayout.mat” as the layout filename for your future figures.
> 
> 
> best regards
> Robert
> 
> 
> 
>> On 12 May 2015, at 10:17, Anna Wieczorek-Taraday <anna.wieczorek.taraday at gmail.com> wrote:
>> 
>> Dear Fieldtrippers, 
>> 
>> I have a problem while reading EEG (EGI) electrode location file to FieldTrip.
>> I am using EGI Amp 300, 64-channel cap, data were exported to .raw files.
>> 
>> When I read locations to EEGLAB, it works well  (lilnk to pictures || see pic. eeglab_chanlocs.jpg). The layout corresponds with the actual electrode placement in the cap.
>> When I read the same file into FieldTrip, the electrodes seem to have similar layout (see pic. fieldtrip_chanlocs.jpg). 
>> However, it seems like the electrodes are confined within the plot too much. Electrodes E61:E64 should be outside of boundaries of the layout plot.
>> 
>> I was wondering whether anybody else had similar issue and did overcome it? Could anybody suggest what is wrong and how can I read the locations properly?
>> Any support will be appreciated.
>> 
>> I am using Matlab 2015, eeglab eeglab13_4_4b and the latest version of fieldtrip.
>> 
>> ***************************************
>> 
>> 
>> Here is code I used to read these locations:
>> 
>> cfg.layout      = 'C:\Users\annwie\Documents\awt_chanlocs\GSN-HydroCel_64.sfp'; 
>> cfg.feedback    = 'yes';
>> layout          = ft_prepare_layout(cfg);
>> 
>> 
>> Here is the code that I used to preprocess my data in Fieldtrip:
>> 
>> cfg = [];
>> cfg.trialfun = 'ft_trialfun_general';
>> cfg.dataset = '136.set';
>> cfg.trialdef.eventtype  = 'trigger';
>> cfg.trialdef.eventvalue = 'DIN8'
>> cfg.trialdef.prestim    = 0.5;
>> cfg.trialdef.poststim   = 2.5;
>> cfg = ft_definetrial(cfg);
>> 
>> cfg.lpfilter = 'no';
>> cfg.hpfilter = 'yes';
>> cfg.hpfreq = 0.3;
>> data = ft_preprocessing(cfg);
>> 
>> Anna Wieczorek-Taraday.
>> 
>> PhD Student   
>> Nencki Institute of Experimental Biology
>> Pasteur Street 3, 02-093 Warsaw, Poland
>> 
>> Warsaw University of Social Sciences and Humanities
>> Chodakowska Street 19/31, 03-815 Warsaw, Poland
>> _______________________________________________
>> fieldtrip mailing list
>> fieldtrip at donders.ru.nl
>> http://mailman.science.ru.nl/mailman/listinfo/fieldtrip
> 
> _______________________________________________
> fieldtrip mailing list
> fieldtrip at donders.ru.nl
> http://mailman.science.ru.nl/mailman/listinfo/fieldtrip
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://mailman.science.ru.nl/pipermail/fieldtrip/attachments/20150512/bc23a779/attachment-0002.html>