compactness_xld (Operator)

Name

compactness_xld — Shape factor for the compactness of contours or polygons.

Synopsis

compactness_xld(XLD : : : Compactness)

Description

The operator compactness_xld calculates the compactness of each input contour or polygon in XLD. The input contour or polygon must not intersect itself, otherwise the resulting parameter is not meaningful (Whether the input contour or polygon intersects itself or not can be determined with test_self_intersection_xld). If the input contour or polygon is not closed it will be closed automatically.

Calculation:

If L is the length and F
the area enclosed by the contour or polygon the shape factor 
Compactness 
is defined as:

                     Compactness = L^2 / (4 F pi))

The shape factor Compactness of a circle is 1. If the contour or polygon encloses an elongated area Compactness is larger than 1. The operator compactness_xld responds to the course of the contour or polygon (roughness). If more than one contour or polygon is passed, the shape factors are stored in a tuple in the same order as the respective contours or polygons in XLD.

Parameters

XLD (input_object)	xld(-array) → object
Contours or polygons to be examined.

Compactness (output_control)	real(-array) → (real)
Compactness of the input contours or polygons.
Assertion: (Compactness >= 1.0) || (Compactness == 0)

Result

The operator compactness_xld returns the value 2 (H_MSG_TRUE) if the input is not empty. The behavior in case of empty input (no input contours available) is set via the operator set_system('no_object_result',<Result>). If necessary an exception is raised.

Parallelization Information

compactness_xld is reentrant and automatically parallelized (on tuple level).

Possible Predecessors

gen_contours_skeleton_xld, edges_sub_pix, threshold_sub_pix, gen_contour_polygon_xld, test_self_intersection_xld

Alternatives

circularity_xld, convexity_xld, eccentricity_xld

See also

area_center_xld, select_shape_xld

Module

Foundation