FieldTrip

Note that this reference documentation is identical to the help that is displayed in Matlab when you type “help ft_prepare_concentricspheres”.

  FT_PREPARE_CONCENTRICSPHERES creates a EEG volume conductor model with
  multiple concentric spheres.
 
  Use as
    vol = ft_prepare_concentricspheres(cfg)
 
  The input configuration should contain
    cfg.headshape     = a filename containing headshape, a Nx3 matrix with surface 
                        points, or a structure with a single or multiple boundaries
    cfg.conductivity  = conductivity values for the model (default = [0.3300 1 0.0042 0.3300])
    cfg.fitind        = indices of shapes to use for fitting the center (default = 'all')
    cfg.nonlinear     = 'yes' or 'no' (default = 'yes')
    cfg.feedback      = 'yes' or 'no' (default = 'yes')
 
  Example:
 
    % first create 4 surfaces that represent the inner_skull_surface, csf, outer_skull_surface and skin_surface
    radius = [86 88 92 100];
    headshape = [];
    for i=1:4
      pnt = randn(100,3);
      for j=1:size(pnt,1)
        pnt(j,:) = pnt(j,:) ./ norm(pnt(j,:));
      end
      headshape(i).pnt = radius(i) .* pnt + 0.1*randn(size(pnt));
    end
 
    % then construct a volume conduction model of the head by fitting 4 concentric spheres
    cfg = [];
    cfg.headshape    = headshape;
    cfg.conductivity = [0.3300 1 0.0042 0.3300]
    [vol, cfg] = prepare_concentricspheres(cfg)