Table 2:

Summary of the differential geometry properties of the basic solid shapes

Basic shape	Minimal curvature	Maximal curvature	Minimum curvature directions
cylinder-like shape	~0	> 0, in a range [c1, c2]	parallel
blob-like shape	> 0, in a range [c1, c2]	> 0, in a range [c1, c2]	random
planar-like shape	~0	~0	random

Note: For non-solid shapes, such as the airways, the maximal curvature on the surface is negative.