[FieldTrip] Too many dipoles in Beamformer Analysis?

[Helen Wieffering]

Hi Tzvetan,

Thank you for your quick reply! You are right - I see I had the
cfg.grid.unit accidentally set to 'mm' instead of 'cm'. Changing this left
me with 1,484 dipoles and an excellent computation time.

Thanks again,
Helen

On Thu, Jul 23, 2015 at 12:36 PM, Tzvetan Popov <
tzvetan.popov at uni-konstanz.de> wrote:

> Hi Helen,
> this isn’t normal and is likely due to mismatch in units. I suspect the
> error somewhere in cfg.grid.resolution = XX;
> during the call to ft_prepare_leadfield.
> best
> tzvetan
>
>
> > Dear Fieldtrip Users,
> >
> > I'm in the midst of computing Beamformer source analysis with my EEG
> data, (I am a new user of FieldTrip), and am experiencing extraordinarily
> long computation times.
> >
> > Using my own data, with the FieldTrip template vol.mat headmodel,
> FieldTrip computes a leadfield with 1,472,505 dipoles inside the brain.
> This alone takes my computer 3 hours to compute, whereafter source analysis
> still has to take place ... taking another 3 hours.
> >
> > This number of dipoles seems (to me) abnormally high - but apart from
> taking so long, the code runs fine without any errors.
> >
> > Is anyone able to weigh in on whether or not I've gone wrong somewhere?
> Happy to include code as needed.
> >
> > Thanks very much!
> >
> > Helen Wieffering
> > Bowdoin College
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> > fieldtrip at donders.ru.nl
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>
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