convexity_xldconvexity_xldconvexity_xldConvexityXldConvexityXld (Operator)

Name

convexity_xldconvexity_xldconvexity_xldConvexityXldConvexityXld — Shape factor for the convexity of contours or polygons.

Signature

Description

The operator convexity_xldconvexity_xldconvexity_xldConvexityXldConvexityXld 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_xldtest_self_intersection_xldtest_self_intersection_xldTestSelfIntersectionXldTestSelfIntersectionXld). If the input contour or polygon is not closed it will be closed automatically.

Calculation:

             If Fc is the area of the convex hull and Fo the area
             enclosed by the original contour or polygon the shape factor
             ConvexityConvexityConvexityConvexityconvexity is defined as:

                  ConvexityConvexityConvexityConvexityconvexity = Fo / Fc

The shape factor ConvexityConvexityConvexityConvexityconvexity is 1 if the contour or polygon is convex (e.g., a rectangle, circle, etc.). If there are indentations ConvexityConvexityConvexityConvexityconvexity is smaller than 1.

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 XLDXLDXLDXLDXLD.

Parallelization

• Multithreading type: reentrant (runs in parallel with non-exclusive operators).
• Multithreading scope: global (may be called from any thread).
• Automatically parallelized on tuple level.

Parameters

Result

The operator convexity_xldconvexity_xldconvexity_xldConvexityXldConvexityXld 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>)set_system("no_object_result",<Result>)set_system("no_object_result",<Result>)SetSystem("no_object_result",<Result>)SetSystem("no_object_result",<Result>). If necessary an exception is raised.

Possible Predecessors

gen_contours_skeleton_xldgen_contours_skeleton_xldgen_contours_skeleton_xldGenContoursSkeletonXldGenContoursSkeletonXld, edges_sub_pixedges_sub_pixedges_sub_pixEdgesSubPixEdgesSubPix, threshold_sub_pixthreshold_sub_pixthreshold_sub_pixThresholdSubPixThresholdSubPix, gen_contour_polygon_xldgen_contour_polygon_xldgen_contour_polygon_xldGenContourPolygonXldGenContourPolygonXld, test_self_intersection_xldtest_self_intersection_xldtest_self_intersection_xldTestSelfIntersectionXldTestSelfIntersectionXld

See also

area_center_xldarea_center_xldarea_center_xldAreaCenterXldAreaCenterXld, select_shape_xldselect_shape_xldselect_shape_xldSelectShapeXldSelectShapeXld, shape_trans_xldshape_trans_xldshape_trans_xldShapeTransXldShapeTransXld

Module

Foundation