Transitions of the pre-symmetry set

The symmetry set (SS) and its subset the medial axis (MA), can be used to describe a shape. The representation of the SS in parameter space is called the pre-symmetry set. Changes in the shape are directly related to the so-called transitions (topological changes) of the SS. They have also effect on the pre-SS. Since the pre-SS can be used to represent the shape efficiently, it is important to study the transitions of the pre-SS and their impact. We present these transitions, as well as the presence of the MA in the pre-SS.