Fig. 3.

Examples of prior shapes (cut at arbitrary plane) generated using hyperparameters estimated from the HCP b = 1500 data (outer shell) and the HCP b = 5000 (inner shell). The solid, dashed and dotted shapes represent three different realisations drawn from the distribution of possible shapes. On the left hand side the priors were drawn independently for the two shells and on the right they were drawn from the multi-shell model (Eq. (16)). Note how in the absence of data, the expected shape is approximately spherical (isotropic diffusion) and that the (relative) variability is greater for the inner shell. Note also that for the multi-shell model (right hand size) the shapes covary across the shells.