 Thus, accurately establishing a dense point-to-point correspondence across heterogeneous scans with sufficient diversity in terms of identities, ethnicities, or expressions becomes essential.
<meaning-changed>  Thus, accurately establishing a dense point-to-point correspondence across heterogeneous scans with sufficient diversity in terms of identities, ethnicities, or expressions becomes essential.
 Hence, to increase the descriptive power of a 3DMM, accurately establishing dense correspondence across heterogeneous scans with sufficient diversity in terms of identities, ethnicities, or expressions becomes essential.