Tangent Space
•Can compute a hyperplane tangent to the hypersphere at a point in preshape space.
•Project all points onto that plane.
•All distances Euclidean.  Average shape easy to find.
•This is reasonable when all shapes similar.
•In this case, all distances are similar too.
–Note that when r is small, r, 2sin(r /2), sin(r) are all similar.