convexity_xld — Shape factor for the convexity of contours or polygons.
The operator convexity_xld calculates the convexity for each input contour or polygon. 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 is the area of the convex hull and the area enclosed by the original contour or polygon the shape factor Convexity is defined as:
If more than one contour or polygon is passed, the numerical results of the shape factor are stored in a tuple in the same order as the respective contours or polygons in XLD.
Contours or polygons to be examined.
Convexity of the input contours or polygons.
Assertion: Convexity <= 1
The operator convexity_xld returns the value 2 (H_MSG_TRUE) if the input is not empty. The behavior in case of empty input (no input contour available) is set via the operator set_system('no_object_result',<Result>). If necessary an exception is raised.
gen_contours_skeleton_xld, edges_sub_pix, threshold_sub_pix, gen_contour_polygon_xld, test_self_intersection_xld
area_center_xld, select_shape_xld, shape_trans_xld