[FieldTrip] Coordinate System (Align electrode positions) Brainstrom VS fieldtrip
Hamza Fawzi Altakroury (Alumni)
hamzaf at sabanciuniv.edu
Wed Jun 25 13:41:21 CEST 2014
I was checking the one of the Fieldtrip's pages to perform an have change
the coordinate system of my electrodes position
For doing an alignment, the fiducials positions should be given, I did not
have them first, so I use the brainstorm toolbox to get them from the
In brainstrom I found this equation for transforming from voxel to mm.
(given the voxel size)
Position_mm = Position_voxel .* Voxel_size.
While in fieldtrip I found another statement which gives (given the
transformation matrix) a different answer:
warp_apply(vox2head, vox_Nas, 'homogenous');
For example using brainstorm equation I got:
NAS = [117.1920 215.8287 118.9998]
And using the fieldtrip function, I got:
NAS = [14.3973 49.3926 49.6322]
What is the difference between the two?
Hamza Fawzi Altakroury
Graduate student - MA
Faculty of Engineering and Natural Sciences
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