moments_xldmoments_xldMomentsXldMomentsXld (Operator)

Name

moments_xldmoments_xldMomentsXldMomentsXld — Geometric moments , , and of contours or polygons.

moments_xldmoments_xldMomentsXldMomentsXldMomentsXld calculates the moments (M20M20M20M20m20, M02M02M02M02m02, and M11M11M11M11m11) of the region enclosed by the contours or polygons XLDXLDXLDXLDXLD. See moments_region_2ndmoments_region_2ndMomentsRegion2ndMomentsRegion2ndMomentsRegion2nd 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_xldMomentsXldMomentsXldMomentsXld will artificially close the contours or polygons.

It should be noted that moments_xldmoments_xldMomentsXldMomentsXldMomentsXld 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_xldTestSelfIntersectionXldTestSelfIntersectionXldTestSelfIntersectionXld can be used. If the contour or polygon intersects itself, useful values for the moments can be calculated with moments_points_xldmoments_points_xldMomentsPointsXldMomentsPointsXldMomentsPointsXld.

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.