HALCON Reference Manual 10.0.2

moments_xldmoments_xldmoments_xldMomentsXldMomentsXld (Operator)

Name

moments_xldmoments_xldmoments_xldMomentsXldMomentsXld — Geometric moments M20, M02, and M11 of contours or polygons.

moments_xldmoments_xldmoments_xldMomentsXldMomentsXld calculates the moments (M20M20M20M20m20, M02M02M02M02m02, and M11M11M11M11m11) of the region enclosed by the contours or polygons XLDXLDXLDXLDXLD. See moments_region_2ndmoments_region_2ndmoments_region_2ndMomentsRegion2ndMomentsRegion2nd for the definition of these features. The moments are computed by applying Green's theorem using only the points on the contour or polygon, i.e., no region is generated explicitly for the purpose of calculating the features. It is assumed that the contours or polygons are closed. If this is not the case moments_xldmoments_xldmoments_xldMomentsXldMomentsXld will artificially close the contours or polygons.

It should be noted that moments_xldmoments_xldmoments_xldMomentsXldMomentsXld 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_xldtest_self_intersection_xldTestSelfIntersectionXldTestSelfIntersectionXld can be used. If the contour or polygon intersects itself, useful values for the moments can be calculated with moments_points_xldmoments_points_xldmoments_points_xldMomentsPointsXldMomentsPointsXld.

If more than one contour or polygon is passed, the results are stored in tuples in the same order as the respective contours or polygons in XLDXLDXLDXLDXLD.