FT_PLOT_SENS visualizes the EEG, MEG or NIRS sensor array.

 Use as
   ft_plot_sens(sens, ...)
 where the first argument is the sensor array as returned by FT_READ_SENS or
 by FT_PREPARE_VOL_SENS.

 Optional input arguments should come in key-value pairs and can include
   'label'           = show the label, can be 'off', 'label', 'number' (default = 'off')
   'chantype'        = string or cell-array with strings, for example 'meg' (default = 'all')
   'unit'            = string, convert the sensor array to the specified geometrical units (default = [])
   'fontcolor'       = string, color specification (default = 'k')
   'fontsize'        = number, sets the size of the text (default = 10)
   'fontunits'       =
   'fontname'        =
   'fontweight'      =

 The following options apply to MEG magnetometers and/or gradiometers
   'coil'            = true/false, plot each individual coil (default = false)
   'orientation'     = true/false, plot a line for the orientation of each coil (default = false)
   'coilshape'       = 'point', 'circle', 'square', or 'sphere' (default is automatic)
   'coilsize'        = diameter or edge length of the coils (default is automatic)
 The following options apply to EEG electrodes
   'elec'            = true/false, plot each individual electrode (default = false)
   'orientation'     = true/false, plot a line for the orientation of each electrode (default = false)
   'elecshape'       = 'point', 'circle', 'square', or 'sphere' (default is automatic)
   'elecsize'        = diameter of the electrodes (default is automatic)
 The following options apply to NIRS optodes
   'opto'            = true/false, plot each individual optode (default = false)
   'orientation'     = true/false, plot a line for the orientation of each optode (default = false)
   'optoshape'       = 'point', 'circle', 'square', or 'sphere' (default is automatic)
   'optosize'        = diameter of the optodes (default is automatic)

 The following options apply when electrodes/coils/optodes are NOT plotted individually
   'style'           = plotting style for the points representing the channels, see plot3 (default = [])
   'marker'          = marker type representing the channels, see plot3 (default = '.')
 The following options apply when electrodes/coils/optodes are plotted individually
   'facecolor'       = [r g b] values or string, for example 'brain', 'cortex', 'skin', 'black', 'red', 'r', or an Nx3 or Nx1 array where N is the number of faces (default is automatic)
   'edgecolor'       = [r g b] values or string, for example 'brain', 'cortex', 'skin', 'black', 'red', 'r', color of channels or coils (default is automatic)
   'facealpha'       = transparency, between 0 and 1 (default = 1)
   'edgealpha'       = transparency, between 0 and 1 (default = 1)

 Example
   sens = ft_read_sens('Subject01.ds');
   figure; ft_plot_sens(sens, 'coilshape', 'point', 'style', 'r*')
   figure; ft_plot_sens(sens, 'coilshape', 'circle')
   figure; ft_plot_sens(sens, 'coilshape', 'circle', 'coil', true, 'chantype', 'meggrad')
   figure; ft_plot_sens(sens, 'coilshape', 'circle', 'coil', false, 'orientation', true)

 See also FT_READ_SENS, FT_PLOT_HEADSHAPE, FT_PLOT_VOL