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.
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) |
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.
threshold__, regiongrowing__, connection
compactness, convexity, excentricity
contlength, area_center, select_shape