mne.channels.read_dig_montage

mne.channels.read_dig_montage(hsp=None, hpi=None, elp=None, point_names=None, unit='auto', fif=None, transform=True, dev_head_t=False)

Read subject-specific digitization montage from a file

Parameters:

hsp : None | str | array, shape (n_points, 3)

If str, this corresponds to the filename of the headshape points. This is typically used with the Polhemus FastSCAN system. If numpy.array, this corresponds to an array of positions of the headshape points in 3d. These points are assumed to be in the native digitizer space and will be rescaled according to the unit parameter.

hpi : None | str | array, shape (n_hpi, 3)

If str, this corresponds to the filename of Head Position Indicator (HPI) points. If numpy.array, this corresponds to an array of HPI points. These points are in device space.

elp : None | str | array, shape (n_fids + n_hpi, 3)

If str, this corresponds to the filename of electrode position points. This is typically used with the Polhemus FastSCAN system. Fiducials should be listed first: nasion, left periauricular point, right periauricular point, then the points corresponding to the HPI. If numpy.array, this corresponds to an array of digitizer points in the same order. These points are assumed to be in the native digitizer space and will be rescaled according to the unit parameter.

point_names : None | list

If list, this corresponds to a list of point names. This must be specified if elp is defined.

unit : ‘auto’ | ‘m’ | ‘cm’ | ‘mm’

Unit of the digitizer files (hsp and elp). If not ‘m’, coordinates will be rescaled to ‘m’. Default is ‘auto’, which assumes ‘m’ for *.hsp and *.elp files and ‘mm’ for *.txt files, corresponding to the known Polhemus export formats.

fif : str | None

FIF file from which to read digitization locations. If str (filename), all other arguments are ignored.

New in version 0.12.

transform : bool

If True, points will be transformed to Neuromag space. The fidicuals, ‘nasion’, ‘lpa’, ‘rpa’ must be specified in the montage file. Useful for points captured using Polhemus FastSCAN. Default is True.

dev_head_t : bool

If True, a Dev-to-Head transformation matrix will be added to the montage. To get a proper dev_head_t, the hpi and the elp points must be in the same order. If False, an identity matrix will be added to the montage. Default is False.

Returns:

montage : instance of DigMontage

The digitizer montage.

See also

read_montage
Function to read generic EEG templates

Notes

All digitized points will be transformed to head-based coordinate system if transform is True and fiducials are present.

New in version 0.9.0.