[FieldTrip] rpa/nas/lpa coordinates

[Elena Orekhova]

Hi
I Just started to use Fieldtrip with my Neuromag MEG data and try to follow  the example script
‘read_neuromag_mri_and_create_single-subject_grids_in_individual_head_space_that_are_all_aligned_in_mni_space’


The instruction suggests to take voxel coordinates of fiduscials from the Neuromag
GUI for MRI-MEG Integration. I have already performed this step and saved the
transformed mri in the /sets/XXX.fif file.

Should I write any  rpa/nas/lpa coordinates in this case?

cfg.fiducial.rpa  = [y x z];

cfg.fiducial.nas  = [y x z];

cfg.fiducial.lpa  = [y x z];

I have 2 4X4 transformations in the .fif file, not sure what they mean.

mri.hdr.trans.trans

0.9913    0.1210    0.0518   -0.0032
   -0.0948    0.9291   -0.3574    0.0254
   -0.0914    0.3494    0.9325   -0.0519
         0         0         0    1.0000
mri.hdr.voxel_trans.trans

   -0.0000   -0.0000   -0.0010    0.1058
   -0.0005    0.0000    0.0000    0.1597
         0   -0.0005    0.0001    0.1058
         0         0         0    1.0000

I'll be most grateful for the help!
Regards,
Elena






________________________________
Elena V Orekhova, Ph.D.
Inst. Neuroscience and Physiology
University of Gothenburg
S-413 45 Gothenburg, Sweden
phone: +46 31 342 48 02
elena at neuro.gu.se
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://mailman.science.ru.nl/pipermail/fieldtrip/attachments/20110521/4d416c5a/attachment.html>