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a2a3f5e86c
Improve robustness for ellipse fitting #26773 ### Pull Request Readiness Checklist Related to #26694 Current noise addition is not very good because for example it turns degenerate case of one horizontal line into degenerate case of two parallel horizontal lines Improving noise addition leads to improved robustness of algorithms See details at https://github.com/opencv/opencv/wiki/How_to_contribute#making-a-good-pull-request - [x] I agree to contribute to the project under Apache 2 License. - [x] To the best of my knowledge, the proposed patch is not based on a code under GPL or another license that is incompatible with OpenCV - [x] The PR is proposed to the proper branch - [x] There is a reference to the original bug report and related work - [x] There is accuracy test, performance test and test data in opencv_extra repository, if applicable Patch to opencv_extra has the same branch name. - [x] The feature is well documented and sample code can be built with the project CMake
117 lines
4.0 KiB
C++
117 lines
4.0 KiB
C++
// This file is part of OpenCV project.
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// It is subject to the license terms in the LICENSE file found in the top-level directory
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// of this distribution and at http://opencv.org/license.html.
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//
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// Copyright (C) 2016, Itseez, Inc, all rights reserved.
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#include "test_precomp.hpp"
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namespace opencv_test { namespace {
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// return true if point lies inside ellipse
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static bool check_pt_in_ellipse(const Point2f& pt, const RotatedRect& el) {
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Point2f to_pt = pt - el.center;
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double pt_angle = atan2(to_pt.y, to_pt.x);
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double el_angle = el.angle * CV_PI / 180;
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double x_dist = 0.5 * el.size.width * cos(pt_angle + el_angle);
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double y_dist = 0.5 * el.size.height * sin(pt_angle + el_angle);
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double el_dist = sqrt(x_dist * x_dist + y_dist * y_dist);
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return cv::norm(to_pt) < el_dist;
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}
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// Return true if mass center of fitted points lies inside ellipse
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static bool fit_and_check_ellipse(const vector<Point2f>& pts) {
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RotatedRect ellipse = fitEllipseDirect(pts); // fitEllipseAMS() also works fine
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Point2f mass_center;
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for (size_t i = 0; i < pts.size(); i++) {
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mass_center += pts[i];
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}
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mass_center /= (float)pts.size();
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return check_pt_in_ellipse(mass_center, ellipse);
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}
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TEST(Imgproc_FitEllipse_Issue_4515, accuracy) {
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vector<Point2f> pts;
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pts.push_back(Point2f(327, 317));
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pts.push_back(Point2f(328, 316));
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pts.push_back(Point2f(329, 315));
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pts.push_back(Point2f(330, 314));
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pts.push_back(Point2f(331, 314));
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pts.push_back(Point2f(332, 314));
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pts.push_back(Point2f(333, 315));
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pts.push_back(Point2f(333, 316));
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pts.push_back(Point2f(333, 317));
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pts.push_back(Point2f(333, 318));
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pts.push_back(Point2f(333, 319));
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pts.push_back(Point2f(333, 320));
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EXPECT_TRUE(fit_and_check_ellipse(pts));
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}
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TEST(Imgproc_FitEllipse_Issue_6544, accuracy) {
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vector<Point2f> pts;
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pts.push_back(Point2f(924.784f, 764.160f));
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pts.push_back(Point2f(928.388f, 615.903f));
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pts.push_back(Point2f(847.4f, 888.014f));
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pts.push_back(Point2f(929.406f, 741.675f));
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pts.push_back(Point2f(904.564f, 825.605f));
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pts.push_back(Point2f(926.742f, 760.746f));
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pts.push_back(Point2f(863.479f, 873.406f));
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pts.push_back(Point2f(910.987f, 808.863f));
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pts.push_back(Point2f(929.145f, 744.976f));
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pts.push_back(Point2f(917.474f, 791.823f));
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EXPECT_TRUE(fit_and_check_ellipse(pts));
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}
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TEST(Imgproc_FitEllipse_Issue_10270, accuracy) {
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vector<Point2f> pts;
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float scale = 1;
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Point2f shift(0, 0);
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pts.push_back(Point2f(0, 1)*scale+shift);
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pts.push_back(Point2f(0, 2)*scale+shift);
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pts.push_back(Point2f(0, 3)*scale+shift);
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pts.push_back(Point2f(2, 3)*scale+shift);
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pts.push_back(Point2f(0, 4)*scale+shift);
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// check that we get almost vertical ellipse centered around (1, 3)
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RotatedRect e = fitEllipse(pts);
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EXPECT_LT(std::min(fabs(e.angle-180), fabs(e.angle)), 10.);
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EXPECT_NEAR(e.center.x, 1, 1);
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EXPECT_NEAR(e.center.y, 3, 1);
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EXPECT_LT(e.size.width*3, e.size.height);
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}
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TEST(Imgproc_FitEllipse_JavaCase, accuracy) {
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vector<Point2f> pts;
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float scale = 1;
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Point2f shift(0, 0);
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pts.push_back(Point2f(0, 0)*scale+shift);
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pts.push_back(Point2f(1, 1)*scale+shift);
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pts.push_back(Point2f(-1, 1)*scale+shift);
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pts.push_back(Point2f(-1, -1)*scale+shift);
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pts.push_back(Point2f(1, -1)*scale+shift);
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// check that we get almost circle centered around (0, 0)
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RotatedRect e = fitEllipse(pts);
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EXPECT_NEAR(e.center.x, 0, 0.01);
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EXPECT_NEAR(e.center.y, 0, 0.01);
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EXPECT_NEAR(e.size.width, sqrt(2.)*2, 0.4);
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EXPECT_NEAR(e.size.height, sqrt(2.)*2, 0.4);
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}
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TEST(Imgproc_FitEllipse_HorizontalLine, accuracy) {
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vector<Point2f> pts({{-300, 100}, {-200, 100}, {-100, 100}, {0, 100}, {100, 100}, {200, 100}, {300, 100}});
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const RotatedRect el = fitEllipse(pts);
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EXPECT_NEAR(el.center.x, -100, 100);
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EXPECT_NEAR(el.center.y, 100, 1);
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EXPECT_NEAR(el.size.width, 1, 1);
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EXPECT_GE(el.size.height, 150);
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EXPECT_NEAR(el.angle, 90, 0.1);
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}
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}} // namespace
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