Table 11. Generative noise models (test cases) used in the randomized registration trials of Experiment 6.

Noise Covariance	Test Case
	1	2	3	4	5	6	7
Orientation	-	-	-	Surface	Surface	Random-Global	Random-Per-Point
Magnitude: ${\lambda }_1^{1/2}$ (mm)	0.0	0.5	1.0	1.0	0.5	0.5	0.5
Magnitude: ${\lambda }_{2,3}^{1/2}$ (mm)	0.0	0.5	1.0	0.5	1.0	1.0	1.0

This table defines the covariances used to generate the zero-mean, multi-variate, Gaussian noise applied to the source shape in each test case of Experiment 6. The table defines both the eigenvalues (λ ₁, λ ₂, λ ₃) (magnitude) and the eigenvectors (orientation) of the covariance matrices for each test case. Orientation “Surface” defines the eigenvectors relative to the orientation of the surface at each source point, where λ ₁ is the variance in the surface-normal direction and (λ ₂, λ ₃) are the variances in the surface-parallel directions. Orientation “Random-Global” defines the matrix of eigenvectors to be a randomly generated rotation matrix, which is applied globally over the source shape (i.e. every point in the source shape has the same noise model). Orientation “Random-Per-Point” is similar to the “Random-Global” case except that every point in the source shape is associated with a different randomly generated rotation (i.e. every point in the source shape has a different noise model). Orientation “-” means that the noise model is isotropic and thus unaffected by the choice of eigenvectors.