Operator Reference

orientation_xldorientation_xldOrientationXldOrientationXldorientation_xld (Operator)

orientation_xldorientation_xldOrientationXldOrientationXldorientation_xld — Calculate the orientation of contours or polygons.

Signature

orientation_xld(XLD : : : Phi)

Description

The operator orientation_xldorientation_xldOrientationXldOrientationXldorientation_xld calculates the orientation (PhiPhiPhiphiphi) of each input contour or polygon (XLDXLDXLDXLDxld). The operator is based on elliptic_axis_xldelliptic_axis_xldEllipticAxisXldEllipticAxisXldelliptic_axis_xld. In addition, the contour respectively polygon point with maximum distance to the center of gravity is calculated. If the column coordinate of this point is less than the column coordinate of the center of gravity the value of is added to the angle. It is assumed that the contours or polygons are closed. If this is not the case orientation_xldorientation_xldOrientationXldOrientationXldorientation_xld will artificially close the contours or polygons.

It should be noted that orientation_xldorientation_xldOrientationXldOrientationXldorientation_xld only returns useful results if the contour or polygon encloses a region in the plane. In particular, the contour or polygon must not intersect itself. This is particularly important if open contours or polygons are passed because they are closed automatically, which can produce a self-intersection. To test whether the contours or polygons intersect themselves, test_self_intersection_xldtest_self_intersection_xldTestSelfIntersectionXldTestSelfIntersectionXldtest_self_intersection_xld can be used. If the contour or polygon intersects itself, useful values for the orientation can be calculated with orientation_points_xldorientation_points_xldOrientationPointsXldOrientationPointsXldorientation_points_xld.

If more than one contour or polygon is passed, the values of the orientations are stored in a tuple in the same order as the respective contours or polygons in XLDXLDXLDXLDxld.

Execution Information

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

XLDXLDXLDXLDxld (input_object) xld(-array) → object

Contours or polygons to be examined.

PhiPhiPhiphiphi (output_control) angle.rad(-array) → (real)

Orientation of the contours or polygons (radians).

Assertion: - pi < Phi && Phi <= pi

Result

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

Possible Predecessors

gen_contours_skeleton_xldgen_contours_skeleton_xldGenContoursSkeletonXldGenContoursSkeletonXldgen_contours_skeleton_xld, edges_sub_pixedges_sub_pixEdgesSubPixEdgesSubPixedges_sub_pix, threshold_sub_pixthreshold_sub_pixThresholdSubPixThresholdSubPixthreshold_sub_pix, gen_contour_polygon_xldgen_contour_polygon_xldGenContourPolygonXldGenContourPolygonXldgen_contour_polygon_xld, test_self_intersection_xldtest_self_intersection_xldTestSelfIntersectionXldTestSelfIntersectionXldtest_self_intersection_xld

Alternatives

elliptic_axis_xldelliptic_axis_xldEllipticAxisXldEllipticAxisXldelliptic_axis_xld, smallest_rectangle2_xldsmallest_rectangle2_xldSmallestRectangle2XldSmallestRectangle2Xldsmallest_rectangle2_xld

Module

Foundation

Operators