•What is shape? Qualities of points that don’t depend on translation, rotation or scale.
•So describe points
independent of similarity transformation.
1.Remove
translation.
•Simplest way,
translate so point 1 is at origin, then remove point one.
•More elegant,
translate center of mass to origin, remove a point.
2.Scale
so that sum ||Xi||^2 = 1.
•Resulting set of points is called pre-shape.
•Pre because we
haven’t removed rotation yet.
•Notation: , U and X denote sets of normalized
points. Points called Xi and Ui, with coordinates (xi,yi), (ui, vi).