Compute the SSS basis for a given measurement info structure.
mne.Info
The mne.Info
object with information about the sensors and methods of measurement.
str
Origin of internal and external multipolar moment space in meters.
The default is 'auto'
, which means (0., 0., 0.)
when
coord_frame='meg'
, and a head-digitization-based
origin fit using fit_sphere_to_headshape()
when coord_frame='head'
. If automatic fitting fails (e.g., due
to having too few digitization points),
consider separately calling the fitting function with different
options or specifying the origin manually.
int
Order of internal component of spherical expansion.
int
Order of external component of spherical expansion.
str
| None
Path to the '.dat'
file with fine calibration coefficients.
File can have 1D or 3D gradiometer imbalance correction.
This file is machine/site-specific.
str
The coordinate frame that the origin
is specified in, either
'meg'
or 'head'
. For empty-room recordings that do not have
a head<->meg transform info['dev_head_t']
, the MEG coordinate
frame should be used.
str
| None
Basis regularization type, must be “in” or None. “in” is the same algorithm as the “-regularize in” option in MaxFilter™.
If True, do not include reference channels in compensation. This option should be True for KIT files, since Maxwell filtering with reference channels is not currently supported.
str
How to deal with ill-conditioned SSS matrices. Can be “error” (default), “warning”, “info”, or “ignore”.
float
| str
The magenetometer scale-factor used to bring the magnetometers
to approximately the same order of magnitude as the gradiometers
(default 100.), as they have different units (T vs T/m).
Can be 'auto'
to use the reciprocal of the physical distance
between the gradiometer pickup loops (e.g., 0.0168 m yields
59.5 for VectorView).
list
The empty-room projection vectors used to extend the external SSS basis (i.e., use eSSS).
New in version 0.21.
str
| int
| None
Control verbosity of the logging output. If None
, use the default
verbosity level. See the logging documentation and
mne.verbose()
for details. Should only be passed as a keyword
argument.
ndarray
, shape (n_meg, n_moments)The basis that can be used to reconstruct the data.
ndarray
, shape (n_moments, n_good_meg)The (stabilized) pseudoinverse of the S array.
ndarray
, shape (n_moments,)The moments that were kept after regularization.
int
The number of kept moments that were in the internal space.
Notes
This outputs variants of \(\mathbf{S}\) and \(\mathbf{S^\dagger}\) from equations 27 and 37 of [1] with the coil scale for magnetometers already factored in so that the resulting denoising transform of the data to obtain \(\hat{\phi}_{in}\) from equation 38 would be:
phi_in = S[:, :n_use_in] @ pS[:n_use_in] @ data_meg_good
New in version 0.23.
References