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reference:ft_megplanar [2018/08/23 14:43] (current)
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 +=====  FT_MEGPLANAR =====
 +
 +Note that this reference documentation is identical to the help that is displayed in MATLAB when you type "help ft_megplanar"​.
 +
 +<​html><​pre>​
 +  <a href=/​reference/​ft_megplanar><​font color=green>​FT_MEGPLANAR</​font></​a>​ computes planar MEG gradients gradients for raw data or average
 +  event-related field data. It can also convert frequency-domain data that was computed
 +  using <a href=/​reference/​ft_freqanalysis><​font color=green>​FT_FREQANALYSIS</​font></​a>,​ as long as it contains the complex-valued fourierspcrm and not
 +  only the powspctrm.
 + 
 +  Use as
 +     ​[interp] = ft_megplanar(cfg,​ data)
 +  where the input data corresponds to the output from <a href=/​reference/​ft_preprocessing><​font color=green>​FT_PREPROCESSING</​font></​a>,​
 +  <a href=/​reference/​ft_timelockanalysis><​font color=green>​FT_TIMELOCKANALYSIS</​font></​a>​ or <a href=/​reference/​ft_freqanalysis><​font color=green>​FT_FREQANALYSIS</​font></​a>​ (with output='​fourierspcrm'​).
 + 
 +  The configuration should contain
 +    cfg.planarmethod ​  = string, can be '​sincos',​ '​orig',​ '​fitplane',​ '​sourceproject'​ (default = '​sincos'​)
 +    cfg.channel ​       =  Nx1 cell-array with selection of channels (default = '​MEG'​),​ see <a href=/​reference/​ft_channelselection><​font color=green>​FT_CHANNELSELECTION</​font></​a>​ for details
 +    cfg.trials ​        = '​all'​ or a selection given as a 1xN vector (default = '​all'​)
 + 
 +  The methods orig, sincos and fitplane are all based on a neighbourhood interpolation.
 +  For these methods you need to specify
 +    cfg.neighbours ​    = neighbourhood structure, see <a href=/​reference/​ft_prepare_neighbours><​font color=green>​FT_PREPARE_NEIGHBOURS</​font></​a>​
 + 
 +  In the '​sourceproject'​ method a minumum current estimate is done using a large number
 +  of dipoles that are placed in the upper layer of the brain surface, followed by a
 +  forward computation towards a planar gradiometer array. This requires the
 +  specification of a volume conduction model of the head and of a source model. The
 +  '​sourceproject'​ method is not supported for frequency domain data.
 + 
 +  A dipole layer representing the brain surface must be specified with
 +    cfg.inwardshift = depth of the source layer relative to the head model surface (default = 2.5 cm, which is appropriate for a skin-based head model)
 +    cfg.spheremesh ​ = number of dipoles in the source layer (default = 642)
 +    cfg.pruneratio ​ = for singular values, default is 1e-3
 +    cfg.headshape ​  = a filename containing headshape, a structure containing a
 +                      single triangulated boundary, or a Nx3 matrix with surface
 +                      points
 +  If no headshape is specified, the dipole layer will be based on the inner compartment
 +  of the volume conduction model.
 + 
 +  The volume conduction model of the head should be specified as
 +    cfg.headmodel ​    = structure with volume conduction model, see <a href=/​reference/​ft_prepare_headmodel><​font color=green>​FT_PREPARE_HEADMODEL</​font></​a>​
 + 
 +  The following cfg fields are optional:
 +    cfg.feedback
 + 
 +  To facilitate data-handling and distributed computing you can use
 +    cfg.inputfile ​  ​= ​ ...
 +    cfg.outputfile ​ =  ...
 +  If you specify one of these (or both) the input data will be read from a *.mat
 +  file on disk and/or the output data will be written to a *.mat file. These mat
 +  files should contain only a single variable, corresponding with the
 +  input/​output structure.
 + 
 +  See also <a href=/​reference/​ft_combineplanar><​font color=green>​FT_COMBINEPLANAR</​font></​a>,​ FT_NEIGHBOURSELECTION
 +</​pre></​html>​