[FieldTrip] ft_prepare_vol_sens-missing .mat file

Thu Jun 14 10:56:49 CEST 2012

Hi Tzvetan,

Thank you very much for your reply.

I am using the MNI surface meshes from the NeuroScan Curry Software as I had trouble in generating the MRI based headmodels.

I had trouble with the MNI surface meshes as well but as Alex suggested earlier in the "Headmodel with NeuroScan meshes" discussion thread I managed to overcome the problems after smoothing them. When I ran the ft_prepare_headmodel with the new smoothed meshes the program ran without explicitly giving me any errors(including om_minverser), but now with your comment I understand that om has not run succesfully to create the mat file.

I am attaching the figure with the smoothed meshes to have a look whether you observe an intersecting mesh.

Please let me know if you have any comments on my procedure.

Many Thanks.



From: fieldtrip-bounces at science.ru.nl [fieldtrip-bounces at science.ru.nl] on behalf of Tzvetan Popov [tzvetan.popov at uni-konstanz.de]
Sent: Thursday, 14 June 2012 5:17 PM
To: FieldTrip discussion list
Subject: Re: [FieldTrip] ft_prepare_vol_sens-missing .mat file

Hi Imali,

in this case your meshes probably touch somewhere so that om doesn't created the bem model at all and as a consequence didn't wrote the mat file. You should go back in the segmentation procedure and play around with the option "cfg.threshold", plot the meshes and make sure they do not touch.
Good luck

Dear fieldtrip users,

I am using a BEM (using OPENMEEG) created volume conduction model, and in order to  prepare lead fields I loaded the electrode array with,
elec = ft_read_sens('mydirectory\standard_1020.elc');

The I used the function,

[vol, sens] = ft_prepare_vol_sens(vol, elec);
However this give as error,

??? Reference to non-existent field 'mat'.

Error in ==> ft_prepare_vol_sens at 419
        if size(vol.mat,1)~=size(vol.mat,2) && size(vol.mat,1)==length(sens.elecpos)

Error in ==> curry_leadField at 15
  [vol, sens] = ft_prepare_vol_sens(vol, elec);

The vol created with the OPENMEEG only contains the following fields,
vol =

             bnd: [1x3 struct]
            cond: [0.3300 0.0042 0.3300]
    skin_surface: 1
          source: 3
            type: 'openmeeg'
            unit: 'mm'
            cfg: [1x1 struct]

Can someone please help me with this error, any advice and comment will be highly appreciated.
Thank you very much!


Imali Thanuja Hettiarachchi
PhD Candidate
Centre for Intelligent Systems research
Deakin University, Geelong 3217, Australia.

Mobile : +61430321972
Email: ith at deakin.edu.au<mailto:ith at deakin.edu.au>


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Tzvetan Popov
Clinical Psychology
University of Konstanz
Box 23
78457 Konstanz, GERMANY
Phone: 0049-7531-883086
Fax:      0049-7531-884601
Email:  tzvetan.popov at uni-konstanz.de<mailto:tzvetan.popov at uni-konstanz.de>

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