compactness — Shape factor for the compactness of a region.
compactness calculates the compactness of the input regions.
If L is the length of the contour (see
contlength) and F the area of the region the shape
factor C is defined as:
C = max(1,C')
In the documentation of this chapter (Regions / Features), you can find an image illustrating regions which vary in their compactness.
The shape factor C of a circle is 1. If the region
is long or has holes C is larger than 1.
compactness responds to the course of the contour
(roughness) and to holes. The value of C is clipped to 1.0,
because the pixel area of a region can only be an approximation of a
real circle's area. This approximation error is bigger for small
regions than for large regions.
In case of an empty region the operator
compactness returns the
value 0 if no other behavior was set (see
If more than one region is passed the numerical values of the shape
factor are stored in a tuple, the position of a value in the tuple corresponding
to the position of the region in the input tuple.
Region(s) to be examined.
Compactness of the input region(s).
Compactness >= 1.0 || Compactness == 0
compactness returns the value 2 (H_MSG_TRUE)
if the input is not empty.
The behavior in case of empty input (no input regions available) is
set via the operator
The behavior in case of empty region (the region is the empty set) is set via
If necessary an exception is raised.