Note that this reference documentation is identical to the help that is displayed in Matlab when you type “help ft_datatype_vol”.
FT_DATATYPE_SOURCE describes the FieldTrip MATLAB structure for volume data The vol data structure represents data on a regular volumetric 3-D grid, like an anatomical MRI, a functional MRI, etc. It can also represent a source reconstructed estimate of the activity measured with MEG. In this case the source reconstruction is estimated or interpolated on the regular 3-D dipole grid (like a box). An example vol structure is dim: [181 217 181] the dimensionality of the 3D volume transform: [4x4 double] affine transformation matrix for mapping the voxel coordinates to the head coordinate system anatomy: [181x217x181 double] numeric data, in this case anatomical information Required fields: - transform, dim Optional fields: - anatomy, prob, stat, grey, white, csf, or any other field with dimensions that are consistent with dim Deprecated fields: - none Obsoleted fields: - none Revision history: (2011) The dimord field was deprecated and we agreed that volume data should be 3-dimensional and not N-dimensional with arbitary dimensions. In case time-frequency recolved data has to be represented on a 3-d grid, the source representation should be used. (2010) The dimord field was added by some functions, but not by all (2003) The initial version was defined See also FT_DATATYPE and FT_DATATYPE_xxx