Shape factor for the convexity of a region.
The operator convexity calculates the convexity of each input region of Regions.
Calculation: If Fc is the area of the convex hull and Fo the
original area of the region the shape factor C
is defined as:
C = Fo / Fc
The shape factor C is 1 if the region is convex (e.g., rectangle,
circle etc.). If there are indentations or holes C is smaller than 1.
In case of an empty region the operator convexity 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 contour length 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. | |
|
Convexity (output_control) |
real(-array) -> real |
| Convexity of the input region(s). | |
| Assertion: Convexity <= 1 | |
The operator convexity 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 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 handling is raised.
convexity is reentrant and automatically parallelized (on tuple level).
threshold, regiongrowing, connection
select_shape, area_center, shape_trans
Region processing
