[FieldTrip] Neuromag coordinate transformation
parham hashemzadeh
ph442 at cam.ac.uk
Fri May 13 20:21:59 CEST 2016
Dear All
I have read in some data (MNE-sample data set). I have this command in
the script
hdr = ft_read_header(raw_data_filename); %your fif-filename
hdr.grad gives the below structure
ans =
balance: [1x1 struct]
chanori: [306x3 double]
chanpos: [306x3 double]
chantype: {306x1 cell}
chanunit: {306x1 cell}
coilori: [510x3 double]
coilpos: [510x3 double]
coordsys: 'neuromag'
label: {306x1 cell}
tra: [306x510 double]
type: 'neuromag306'
unit: 'cm'
It says that I am in "neuromag coordinate" system. The corresponding
number for this coordinate system is device=1.0.
I have a transformation matrix T14.trans (coord system=1 to coord
system=4) that takes me to head coordinate system i.e
T14 =
from: 1
to: 4
trans: [4x4 double]
When I apply the transformation, to the coil position, the sensor array
looks tilted to one side.
But, without the transformation, it looks more reasonable (visually).
Maybe he was tilting !!! My question is:
Is it anyway possible that the transformation T14 has already been
applied by the function hdr = ft_read_header(raw_data_filename);
I have attached a picture of what I am describing.
many thanks
best regards parham hashemzadeh
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