convexity — Shape factor for the convexity of a region.
The operator convexity calculates the convexity of each input
region of Regions.
If is the area of the convex hull and the original area of the region the shape factor C is defined as:
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 the documentation of this chapter (Regions / Features), you can find an image illustrating regions which vary in their convexity.
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 is raised.
threshold,
regiongrowing,
connection
select_shape,
area_center,
shape_trans
Foundation