[FieldTrip] Question on bemcp's and openmeeg's vol.mat

[kgm at tf.uni-kiel.de]

Hi,

I am working with the combined EEG and MEG recording and would like to do
the forward model for the EEG.

So I was trying to use the 'bemcp' and 'openmeeg' as am working on windows
platform. I have the anatomy of my subject (DICOM file stacked and cleaned
using SPM).

When I try to use openmeeg, vol.mat is missing from the vol structure
giving an error message om_minverser.exe doesn't function anymore.

When I try to use 'bemcp', vol.mat contains all NaNs which resulted from
the c12 and c21 matrices being not a square matrix which makes the inverse
to be non-existent and also those matrices consists a large number of
'Inf' entries.

Like it was mentioned on one of the forums, the error might come when the
meshes are generated. I was able to find the index of the vertices from
the Cij matrix, but I couldn't find the actual relation to the
vol.bnd(i).pnt and vol.bnd(i).tri matrices, 'i' representing either brain,
skull or scalp.

Here are all the steps that I have followed.

% reading MRI
mri = ft_read_mri('msGAP724534-0002-00001-000192-01.img');

% segment the brain
cfg = [];
cfg.output = {'brain', 'skull', 'scalp'};
cfg.coordsys = ''; % here I use the RAS coordsys and for the origin 'i'-
interauricular
segmentedmri = ft_volumesegment(cfg, mri);
segmentedmri.anatomy = mri.anatomy;

% prepare mesh
cfg = [];
cfg.tissue = {'brain','skull', 'scalp'};
cfg.numvertices = [3000 2000 1000];
cfg.transform = segmentedmri.transform;
bnd = ft_prepare_mesh(cfg, segmentedmri);

% create head model
cfg = [];
cfg.method = 'openmeeg';
cfg.conductivity = [0.33 0.0041 0.33];
vol = ft_prepare_headmodel(cfg, bnd);

figure;
ft_plot_mesh(vol.bnd(1),'facecolor','none'); %brain
figure;
ft_plot_mesh(vol.bnd(2),'facecolor','none'); %skull
figure;
ft_plot_mesh(vol.bnd(3),'facecolor','none'); %scalp

Any help?

Thanks.
Kidist