of connected components [58]. The Euler number of a 3-D object is then defined
as [58]
x SðÞ¼componentsðÞtunnelsðÞþcavitiesðÞ (14:76)
The Euler number corresponds to the topology of a closed surface rather than
the topology of an object, and thus it cannot differentiate between surfaces from
distinct objects and surfaces originating from the same object, such as an object
with a hole. The Euler number is used as a topology test in 3-D skeletonization
algorithms [94].
14.15.2 Bounding Box
The simplest method to measure the size of an object is to estimate the dimen-
sions of its bounding box, that is, the smallest parallelepiped that contains the
object. This can be done by scanning the 3-D volume and finding the object
voxels with the minimum and maximum ...