Transformation: can be any spatial transformation
within a specified set. The set can include non-linear warps with
arbitrarily large number of Degrees Of Freedom. This transformation
applies to all of the shapes, .
Image generation model:
are intensity scaling
generates the th basis image of a
shape (see section 2.3).
Image measurement model:
where is a spatially uncorrelated Gaussian noise process
Note that all images (,
, , etc) are
treated as vectors of length , where is the number of
voxels in the image.