compactness ( Regions : : : Compactness )

Shape factor for the compactness of a region.

The operator compactness calculates the compactness of the input regions.

Calculation: 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 = L^2 / (4 F pi))
The shape factor C of a circle is 1. If the region is long or has holes C is larger than 1. The operator compactness responds to the course of the contour (roughness) and to holes. In case of an empty region the operator compactness returns the value 0 if no other behavior was set (see set_system). 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.


Parameters

Regions (input_object)
region(-array) -> object
Region(s) to be examined.

Compactness (output_control)
real(-array) -> real
Compactness of the input region(s).
Assertion: (Compactness >= 1.0) || (Compactness == 0)


Result

The operator compactness returns the value TRUE if the input is not empty. The behavior in case of empty input (no input regions available) is set via the operator set_system(::'no_object_result',<Result>:). The behavior in case of empty region (the region is the empty set) is set via set_system(::'empty_region_result',<Result>:). If necessary an exception is raised.


Possible Predecessors

threshold__, regiongrowing__, connection


Alternatives

compactness, convexity, excentricity


See also

contlength, area_center, select_shape



Copyright © 1996-1997 MVTec Software GmbH