Because of the way that the affine registration is coded, there is
no easy hack to make it do a 7 parameter registration where the 7th
parameter is a zoom in all three orthogonal directions.
The routine spm_affsub1.m would need to be modified so that lines
55 and 65 could do something like:
Mat = inv(inv(MG)*spm_matrix([P(1:6)' P(7) P(7) P(7)])*MF);
and:
tmp = inv(inv(MG)*spm_matrix[tP(1:6)' tP(7) tP(7) tP(7)])*MF);
The changes would also need to be probagated through spm_affsub2.m,
spm_affsub3.m, and spm_sn3d.m.
It is all perfectly possible, but it may take a while to actually
re-code.
Regards,
-John
> I'm trying to do a 7 parameter affine registration: this is rigid body
> and 1 scaling factor that is the same for x, y and z (a sort of global
> scaling of the dimension of the head).
> How can I define this in the spm_sn3d script?
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