fitEllipse returns a very far ellipse #26078
Description
System Information
OpenCV python version: 4.10.0
Operating System / Platform: Windows 11
Python version: 3.11.9
Detailed description
When running cv2.fitEllipse on a the points below i got an ellipse that is very far and not related to them.
Subset of the points did not result with same problem.
Steps to reproduce
import cv2
import numpy as np
import matplotlib.pyplot as plt
points = [
[1434, 308], [1434, 309], [1433, 310], [1427, 310], [1427, 312], [1426, 313], [1422, 313], [1422, 314],
[1421, 315], [1415, 315], [1415, 316], [1414, 317], [1408, 317], [1408, 319], [1407, 320], [1403, 320],
[1403, 321], [1402, 322], [1396, 322], [1396, 323], [1395, 324], [1389, 324], [1389, 326], [1388, 327],
[1382, 327], [1382, 328], [1381, 329], [1376, 329], [1376, 330], [1375, 331], [1369, 331], [1369, 333],
[1368, 334], [1362, 334], [1362, 335], [1361, 336], [1359, 336], [1359, 1016], [1365, 1016], [1366, 1017],
[1366, 1019], [1430, 1019], [1430, 1017], [1431, 1016], [1440, 1016], [1440, 308]
]
ellipse = cv2.fitEllipse(np.array(points))
points = np.array(points)
center, axes, angle = ellipse
ellipse_points = cv2.ellipse2Poly((int(center[0]), int(center[1])), (int(axes[0] // 2), int(axes[1] // 2)), int(angle), 0, 360, 1)
plt.figure(figsize=(8, 8))
plt.scatter(points[:, 0], points[:, 1], c='blue', label='Points')
ellipse_polygon = plt.Polygon(ellipse_points, fill=None, edgecolor='red', label='Fitted Ellipse')
plt.gca().add_patch(ellipse_polygon)
plt.gca().set_aspect('equal', adjustable='box')
plt.legend()
plt.show()Issue submission checklist
- I report the issue, it's not a question
- I checked the problem with documentation, FAQ, open issues, forum.opencv.org, Stack Overflow, etc and have not found any solution
- I updated to the latest OpenCV version and the issue is still there
- There is reproducer code and related data files (videos, images, onnx, etc)