[FieldTrip] problems with channel layout autoscaling by ft_prepare_layout

[David Groppe]

Thanks for the email Rodolphe.
It's good to know I'm not the only one who has had this problem.  I
was hoping for a solution that didn't involve editing the code, since
that makes it a pain to update our version of fieldtrip when a new
version is released.  It looks like that might be the only way though.
    cheers,
       -David

On Fri, Jan 14, 2011 at 1:52 PM, Rodolphe Nenert <batrod at gmail.com> wrote:
> David,
> i had the same issue with my own layout. The position of my electrodes was
> not fitting the head, even if the proportion were right, like in your first
> image.
> I solved this problem by multiplying the position with different numbers
> until i found the perfect one.
> This is the part of code that does this:
> lay = ft_prepare_layout(cfg);
> lay.pos(:,1) = 1.5*lay.pos(:,1);
> Replace 1.5 by something that works for you.
> Hope this helps,
> Rodolphe.
>
> On Fri, Jan 14, 2011 at 3:36 PM, David Groppe <dgroppe at cogsci.ucsd.edu>
> wrote:
>>
>> Hi Fieldtripians,
>>   I'm trying to export some EEGLAB data to Fieldtrip and am having
>> trouble plotting the data topographically. I constructed a layout file
>> for my 31 electrodes (see attached) and tried to plot the topography
>> of my data using ft_topoplotER.m.  This produced the attached figures
>> all_chans.jpg and just_scalp_chans.jpg.  The topography should look
>> like that in the attached image, eeglab_topo.jpg.  As you can see, the
>> electrodes are shrunk too far into the head and can be off center.
>> Trying to change the channel layout file to fix this has little effect
>> because ft_prepare_layout.m automatically normalizes the electrode
>> coordinates to fill a unit circle.  Given the topoplots in the
>> fieldtrip tutorial, there's obviously a way around this problem but
>> save for editing the ft_prepare_layout.m, I don't know what to do.
>>     thanks in advance for your help,
>>            -David
>>
>> --
>> David Groppe, Ph.D.
>> dgroppe at cogsci.ucsd.edu
>> http://www.cogsci.ucsd.edu/~dgroppe/
>>
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>
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-- 
David Groppe, Ph.D.
dgroppe at cogsci.ucsd.edu
http://www.cogsci.ucsd.edu/~dgroppe/