Similarity
Intuitively, similarity function should:
- Match our intuitive notion of shape resemblance
- Be invariant under translation, rotation, and scale
- Be easy to compute
Ideally, it should be a metric:
- Non-negative: d(A,B) ? 0 for all A and B
- Identity: d(A,B) = 0 if and only if A=B
- Symmetry: d(A,B) = d(B,A) for all A and B
- Triangle inequality: d(A,B) + d(B,C) ? d(A,C)