elliptic_axis_points_xldelliptic_axis_points_xldEllipticAxisPointsXldEllipticAxisPointsXldelliptic_axis_points_xld (算子)

名称

elliptic_axis_points_xldelliptic_axis_points_xldEllipticAxisPointsXldEllipticAxisPointsXldelliptic_axis_points_xld — 被视为点云的等值椭圆或多边形的参数。

签名

描述

算子 elliptic_axis_points_xldelliptic_axis_points_xldEllipticAxisPointsXldEllipticAxisPointsXldEllipticAxisPointsXldelliptic_axis_points_xld calculates the radii (RaRaRaRarara, RbRbRbRbrbrb) and the orientation (PhiPhiPhiPhiphiphi, in radians) of the ellipse having the same orientation and the same aspect ratio as the point cloud given by the contour or polygon XLDXLDXLDXLDXLDxld (i.e., the order of the points in the contour or polygon is not taken into account). If the contour or polygon is closed (end point = start point), the end point of the contour or polygon is not taken into account to avoid that it receives twice the weight of the other points.

Calculation: If the moments , and are normalized to the area (see moments_points_xldmoments_points_xldMomentsPointsXldMomentsPointsXldMomentsPointsXldmoments_points_xld), the major radius RaRaRaRarara and the minor radius RbRbRbRbrbrb are calculated as: The orientation PhiPhiPhiPhiphiphi, i.e., the angle between the major axis and the x (column) axis, is defined by:

elliptic_axis_points_xldelliptic_axis_points_xldEllipticAxisPointsXldEllipticAxisPointsXldEllipticAxisPointsXldelliptic_axis_points_xld should be used if the contour XLDXLDXLDXLDXLDxld intersects itself or if it is not possible to close the contour using a line from end to start point without self-intersection, because in this case elliptic_axis_xldelliptic_axis_xldEllipticAxisXldEllipticAxisXldEllipticAxisXldelliptic_axis_xld does not produce useful results.可使用 test_self_intersection_xldtest_self_intersection_xldTestSelfIntersectionXldTestSelfIntersectionXldTestSelfIntersectionXldtest_self_intersection_xld 检测轮廓或多边形是否自相交。

如果传递多个轮廓或多边形，结果将按其在 XLDXLDXLDXLDXLDxld 中的顺序存储为元组。

执行信息

• 多线程类型：可重入（与非独占算子并行运行）。
• 多线程作用域：全局（可从任何线程调用）。
• 在元组级别上自动并行化。

参数

复杂度

设 n 为轮廓或多边形的点数。则运行时间为 O(n)。

结果

elliptic_axis_points_xldelliptic_axis_points_xldEllipticAxisPointsXldEllipticAxisPointsXldEllipticAxisPointsXldelliptic_axis_points_xld 在输入不为空时返回 2 ( H_MSG_TRUE )。如果输入为空则可设置行为通过 set_system(::'no_object_result',<Result>:)set_system("no_object_result",<Result>)SetSystem("no_object_result",<Result>)SetSystem("no_object_result",<Result>)SetSystem("no_object_result",<Result>)set_system("no_object_result",<Result>)。如有必要，则抛出异常。

可能的前趋

gen_contours_skeleton_xldgen_contours_skeleton_xldGenContoursSkeletonXldGenContoursSkeletonXldGenContoursSkeletonXldgen_contours_skeleton_xld, edges_sub_pixedges_sub_pixEdgesSubPixEdgesSubPixEdgesSubPixedges_sub_pix, threshold_sub_pixthreshold_sub_pixThresholdSubPixThresholdSubPixThresholdSubPixthreshold_sub_pix, gen_contour_polygon_xldgen_contour_polygon_xldGenContourPolygonXldGenContourPolygonXldGenContourPolygonXldgen_contour_polygon_xld, test_self_intersection_xldtest_self_intersection_xldTestSelfIntersectionXldTestSelfIntersectionXldTestSelfIntersectionXldtest_self_intersection_xld

可能的后继

area_center_points_xldarea_center_points_xldAreaCenterPointsXldAreaCenterPointsXldAreaCenterPointsXldarea_center_points_xld, gen_ellipse_contour_xldgen_ellipse_contour_xldGenEllipseContourXldGenEllipseContourXldGenEllipseContourXldgen_ellipse_contour_xld

替代

elliptic_axis_xldelliptic_axis_xldEllipticAxisXldEllipticAxisXldEllipticAxisXldelliptic_axis_xld, smallest_rectangle2smallest_rectangle2SmallestRectangle2SmallestRectangle2SmallestRectangle2smallest_rectangle2

另见

moments_xldmoments_xldMomentsXldMomentsXldMomentsXldmoments_xld, smallest_circle_xldsmallest_circle_xldSmallestCircleXldSmallestCircleXldSmallestCircleXldsmallest_circle_xld, smallest_rectangle1_xldsmallest_rectangle1_xldSmallestRectangle1XldSmallestRectangle1XldSmallestRectangle1Xldsmallest_rectangle1_xld, smallest_rectangle2_xldsmallest_rectangle2_xldSmallestRectangle2XldSmallestRectangle2XldSmallestRectangle2Xldsmallest_rectangle2_xld, shape_trans_xldshape_trans_xldShapeTransXldShapeTransXldShapeTransXldshape_trans_xld

参考文献

R. Haralick, L. Shapiro “Computer and Robot Vision” Addison-Wesley, 1992, pp. 73-75

模块

基础