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opencv/modules/objdetect/misc/python/test/test_objdetect_aruco.py
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Siddharth Panditrao 0c613de006 Merge pull request #28380 from WalkingDevFlag:fix/charuco-detector-offset-25539
Fix ~0.5px systematic offset in CharucoDetector subpixel refinement #28380

Resolves #25539

### Problem

`CharucoDetector::detectBoard` produces Charuco corner coordinates that are consistently offset by approximately **+0.5 pixels** compared to `findChessboardCorners + cornerSubPix`.

This offset is systematic (mean ≈ −0.5 px when comparing legacy − Charuco) and reproducible across images. Visual inspection also shows that the legacy chessboard detector aligns better with the actual corner locations.

### Root cause

In `charuco_detector.cpp`, the points passed to `cornerSubPix` are manually shifted by `-Point2f(0.5f, 0.5f)` before refinement and then shifted back by `+Point2f(0.5f, 0.5f)` after refinement.

However, `cornerSubPix` refines corners in **absolute image coordinates** and converges to the true saddle point based on image gradients. Shifting the initial guess does not affect the converged result as long as the true corner lies within the refinement window.

The additional `+0.5` shift applied after refinement therefore introduces a constant bias, resulting in:

```

P_out = P_true + 0.5

```

### Solution

Remove the manual `±0.5` coordinate shifts around the `cornerSubPix` call and let the refined result be returned directly.

### Test updates

Updated expected corner values in the following tests:

- `testBoardSubpixelCoords`
- `testSeveralBoardsWithCustomIds`

The previous expected values (e.g. `200`, `250`, `300`) were only correct due to the +0.5px bias introduced by the bug.

`generateImage` creates checkerboard squares of exactly **50 pixels**, which places true corner locations on **pixel boundaries** rather than pixel centers. As a result, the correct subpixel coordinates are:

```

199.5, 249.5, 299.5

```

instead of the previously expected integer values.

After updating the expected values, all **30 Charuco-related tests pass** with the fix applied.

### Verification

I verified the fix using a Python reproducer that compares `CharucoDetector` output against `findChessboardCorners + cornerSubPix`:

- **Before fix:** mean error ≈ −0.501 px  
![before_fix_multilocus](https://github.com/user-attachments/assets/cc812956-c081-4f00-a7e2-78b7427b1235)
![before_fix_zoomed_small](https://github.com/user-attachments/assets/7e6887cb-b09d-47dc-9fcd-03a27b17f310)

- **After fix:** mean error ≈ −0.001 px
![after_fix_multilocus](https://github.com/user-attachments/assets/1c4f8dfa-d0ae-417c-881e-e2a9cbc4b9f1)
![after_fix_zoomed_small](https://github.com/user-attachments/assets/9c325995-fe0b-42f3-bdbb-6754f985e936)

After the change, the Charuco detector output aligns with the legacy chessboard detector both numerically and visually.

### Notes

This change only affects the post-refinement coordinate handling and does not alter detection logic, refinement parameters, or performance.

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
2026-01-28 14:31:54 +03:00

494 lines
22 KiB
Python

#!/usr/bin/env python
# Python 2/3 compatibility
from __future__ import print_function
import os, tempfile, numpy as np
from math import pi
import cv2 as cv
from tests_common import NewOpenCVTests
def getSyntheticRT(yaw, pitch, distance):
rvec = np.zeros((3, 1), np.float64)
tvec = np.zeros((3, 1), np.float64)
rotPitch = np.array([[-pitch], [0], [0]])
rotYaw = np.array([[0], [yaw], [0]])
rvec, tvec = cv.composeRT(rotPitch, np.zeros((3, 1), np.float64),
rotYaw, np.zeros((3, 1), np.float64))[:2]
tvec = np.array([[0], [0], [distance]])
return rvec, tvec
# see test_aruco_utils.cpp
def projectMarker(img, board, markerIndex, cameraMatrix, rvec, tvec, markerBorder):
markerSizePixels = 100
markerImg = cv.aruco.generateImageMarker(board.getDictionary(), board.getIds()[markerIndex], markerSizePixels, borderBits=markerBorder)
distCoeffs = np.zeros((5, 1), np.float64)
maxCoord = board.getRightBottomCorner()
objPoints = board.getObjPoints()[markerIndex]
for i in range(len(objPoints)):
objPoints[i][0] -= maxCoord[0] / 2
objPoints[i][1] -= maxCoord[1] / 2
objPoints[i][2] -= maxCoord[2] / 2
corners, _ = cv.projectPoints(objPoints, rvec, tvec, cameraMatrix, distCoeffs)
originalCorners = np.array([
[0, 0],
[markerSizePixels, 0],
[markerSizePixels, markerSizePixels],
[0, markerSizePixels],
], np.float32)
transformation = cv.getPerspectiveTransform(originalCorners, corners)
borderValue = 127
aux = cv.warpPerspective(markerImg, transformation, img.shape, None, cv.INTER_NEAREST, cv.BORDER_CONSTANT, borderValue)
assert(img.shape == aux.shape)
mask = (aux == borderValue).astype(np.uint8)
img = img * mask + aux * (1 - mask)
return img
def projectChessboard(squaresX, squaresY, squareSize, imageSize, cameraMatrix, rvec, tvec):
img = np.ones(imageSize, np.uint8) * 255
distCoeffs = np.zeros((5, 1), np.float64)
for y in range(squaresY):
startY = y * squareSize
for x in range(squaresX):
if (y % 2 != x % 2):
continue
startX = x * squareSize
squareCorners = np.array([[startX - squaresX*squareSize/2,
startY - squaresY*squareSize/2,
0]], np.float32)
squareCorners = np.stack((squareCorners[0],
squareCorners[0] + [squareSize, 0, 0],
squareCorners[0] + [squareSize, squareSize, 0],
squareCorners[0] + [0, squareSize, 0]))
projectedCorners, _ = cv.projectPoints(squareCorners, rvec, tvec, cameraMatrix, distCoeffs)
projectedCorners = projectedCorners.astype(np.int64)
projectedCorners = projectedCorners.reshape(1, 4, 2)
img = cv.fillPoly(img, [projectedCorners], 0)
return img
def projectCharucoBoard(board, cameraMatrix, yaw, pitch, distance, imageSize, markerBorder):
rvec, tvec = getSyntheticRT(yaw, pitch, distance)
img = np.ones(imageSize, np.uint8) * 255
for indexMarker in range(len(board.getIds())):
img = projectMarker(img, board, indexMarker, cameraMatrix, rvec, tvec, markerBorder)
chessboard = projectChessboard(board.getChessboardSize()[0], board.getChessboardSize()[1],
board.getSquareLength(), imageSize, cameraMatrix, rvec, tvec)
chessboard = (chessboard != 0).astype(np.uint8)
img = img * chessboard
return img, rvec, tvec
class aruco_objdetect_test(NewOpenCVTests):
def test_board(self):
p1 = np.array([[0, 0, 0], [0, 1, 0], [1, 1, 0], [1, 0, 0]], dtype=np.float32)
p2 = np.array([[1, 0, 0], [1, 1, 0], [2, 1, 0], [2, 0, 0]], dtype=np.float32)
objPoints = np.array([p1, p2])
dictionary = cv.aruco.getPredefinedDictionary(cv.aruco.DICT_4X4_50)
ids = np.array([0, 1])
board = cv.aruco.Board(objPoints, dictionary, ids)
np.testing.assert_array_equal(board.getIds().squeeze(), ids)
np.testing.assert_array_equal(np.ravel(np.array(board.getObjPoints())), np.ravel(np.concatenate([p1, p2])))
def test_idsAccessibility(self):
ids = np.arange(17)
rev_ids = ids[::-1]
aruco_dict = cv.aruco.getPredefinedDictionary(cv.aruco.DICT_5X5_250)
board = cv.aruco.CharucoBoard((7, 5), 1, 0.5, aruco_dict)
np.testing.assert_array_equal(board.getIds().squeeze(), ids)
board = cv.aruco.CharucoBoard((7, 5), 1, 0.5, aruco_dict, rev_ids)
np.testing.assert_array_equal(board.getIds().squeeze(), rev_ids)
board = cv.aruco.CharucoBoard((7, 5), 1, 0.5, aruco_dict, ids)
np.testing.assert_array_equal(board.getIds().squeeze(), ids)
def test_identify(self):
aruco_dict = cv.aruco.getPredefinedDictionary(cv.aruco.DICT_4X4_50)
expected_idx = 9
expected_rotation = 2
bit_marker = np.array([[0, 1, 1, 0], [1, 0, 1, 0], [1, 1, 1, 1], [0, 0, 1, 1]], dtype=np.uint8)
check, idx, rotation = aruco_dict.identify(bit_marker, 0)
self.assertTrue(check, True)
self.assertEqual(idx, expected_idx)
self.assertEqual(rotation, expected_rotation)
def test_getDistanceToId(self):
aruco_dict = cv.aruco.getPredefinedDictionary(cv.aruco.DICT_4X4_50)
idx = 7
rotation = 3
bit_marker = np.array([[0, 1, 0, 1], [0, 1, 1, 1], [1, 1, 0, 0], [0, 1, 0, 0]], dtype=np.uint8)
dist = aruco_dict.getDistanceToId(bit_marker, idx)
self.assertEqual(dist, 0)
def test_aruco_detector(self):
aruco_params = cv.aruco.DetectorParameters()
aruco_dict = cv.aruco.getPredefinedDictionary(cv.aruco.DICT_4X4_250)
aruco_detector = cv.aruco.ArucoDetector(aruco_dict, aruco_params)
id = 2
marker_size = 100
offset = 10
img_marker = cv.aruco.generateImageMarker(aruco_dict, id, marker_size, aruco_params.markerBorderBits)
img_marker = np.pad(img_marker, pad_width=offset, mode='constant', constant_values=255)
gold_corners = np.array([[offset, offset],[marker_size+offset-1.0,offset],
[marker_size+offset-1.0,marker_size+offset-1.0],
[offset, marker_size+offset-1.0]], dtype=np.float32)
corners, ids, rejected = aruco_detector.detectMarkers(img_marker)
self.assertEqual(1, len(ids))
self.assertEqual(id, ids[0])
for i in range(0, len(corners)):
np.testing.assert_array_equal(gold_corners, corners[i].reshape(4, 2))
def test_aruco_detector_refine(self):
aruco_params = cv.aruco.DetectorParameters()
aruco_dict = cv.aruco.getPredefinedDictionary(cv.aruco.DICT_4X4_250)
aruco_detector = cv.aruco.ArucoDetector(aruco_dict, aruco_params)
board_size = (3, 4)
board = cv.aruco.GridBoard(board_size, 5.0, 1.0, aruco_dict)
board_image = board.generateImage((board_size[0]*50, board_size[1]*50), marginSize=10)
corners, ids, rejected = aruco_detector.detectMarkers(board_image)
self.assertEqual(board_size[0]*board_size[1], len(ids))
part_corners, part_ids, part_rejected = corners[:-1], ids[:-1], list(rejected)
part_rejected.append(corners[-1])
refine_corners, refine_ids, refine_rejected, recovered_ids = aruco_detector.refineDetectedMarkers(board_image, board, part_corners, part_ids, part_rejected)
self.assertEqual(board_size[0] * board_size[1], len(refine_ids))
self.assertEqual(1, len(recovered_ids))
self.assertEqual(ids[-1], refine_ids[-1])
self.assertEqual((1, 4, 2), refine_corners[0].shape)
np.testing.assert_array_equal(corners, refine_corners)
def test_charuco_refine(self):
aruco_dict = cv.aruco.getPredefinedDictionary(cv.aruco.DICT_6X6_50)
board_size = (3, 4)
board = cv.aruco.CharucoBoard(board_size, 1., .7, aruco_dict)
aruco_detector = cv.aruco.ArucoDetector(aruco_dict)
charuco_detector = cv.aruco.CharucoDetector(board)
cell_size = 100
image = board.generateImage((cell_size*board_size[0], cell_size*board_size[1]))
camera = np.array([[1, 0, 0.5],
[0, 1, 0.5],
[0, 0, 1]])
dist = np.array([0, 0, 0, 0, 0], dtype=np.float32).reshape(1, -1)
# generate gold corners of the ArUco markers for the test
gold_corners = np.array(board.getObjPoints())[:, :, 0:2]*cell_size
# detect corners
markerCorners, markerIds, _ = aruco_detector.detectMarkers(image)
# test refine
rejected = [markerCorners[-1]]
markerCorners, markerIds = markerCorners[:-1], markerIds[:-1]
markerCorners, markerIds, _, _ = aruco_detector.refineDetectedMarkers(image, board, markerCorners, markerIds,
rejected, cameraMatrix=camera, distCoeffs=dist)
charucoCorners, charucoIds, _, _ = charuco_detector.detectBoard(image, markerCorners=markerCorners,
markerIds=markerIds)
self.assertEqual(len(charucoIds), 6)
self.assertEqual(len(markerIds), 6)
for i, id in enumerate(markerIds.reshape(-1)):
np.testing.assert_allclose(gold_corners[id], markerCorners[i].reshape(4, 2), 0.01, 1.)
def test_write_read_dictionary(self):
try:
aruco_dict = cv.aruco.getPredefinedDictionary(cv.aruco.DICT_5X5_50)
markers_gold = aruco_dict.bytesList
# write aruco_dict
fd, filename = tempfile.mkstemp(prefix="opencv_python_aruco_dict_", suffix=".yml")
os.close(fd)
fs_write = cv.FileStorage(filename, cv.FileStorage_WRITE)
aruco_dict.writeDictionary(fs_write)
fs_write.release()
# reset aruco_dict
aruco_dict = cv.aruco.getPredefinedDictionary(cv.aruco.DICT_6X6_250)
# read aruco_dict
fs_read = cv.FileStorage(filename, cv.FileStorage_READ)
aruco_dict.readDictionary(fs_read.root())
fs_read.release()
# check equal
self.assertEqual(aruco_dict.markerSize, 5)
self.assertEqual(aruco_dict.maxCorrectionBits, 3)
np.testing.assert_array_equal(aruco_dict.bytesList, markers_gold)
finally:
if os.path.exists(filename):
os.remove(filename)
def test_charuco_detector(self):
aruco_dict = cv.aruco.getPredefinedDictionary(cv.aruco.DICT_4X4_250)
board_size = (3, 3)
board = cv.aruco.CharucoBoard(board_size, 1.0, .8, aruco_dict)
charuco_detector = cv.aruco.CharucoDetector(board)
cell_size = 100
image = board.generateImage((cell_size*board_size[0], cell_size*board_size[1]))
# Note: Expected values adjusted by -0.5px after fixing the systematic offset bug in charuco_detector.cpp
# The fix removes the incorrect +0.5 offset that was added after cornerSubPix
list_gold_corners = []
for i in range(1, board_size[0]):
for j in range(1, board_size[1]):
list_gold_corners.append((j*cell_size - 0.5, i*cell_size - 0.5))
gold_corners = np.array(list_gold_corners, dtype=np.float32)
charucoCorners, charucoIds, markerCorners, markerIds = charuco_detector.detectBoard(image)
self.assertEqual(len(charucoIds), 4)
for i in range(0, 4):
self.assertEqual(charucoIds[i], i)
np.testing.assert_allclose(gold_corners, charucoCorners.reshape(-1, 2), 0.01, 0.1)
def test_detect_diamonds(self):
aruco_dict = cv.aruco.getPredefinedDictionary(cv.aruco.DICT_6X6_250)
board_size = (3, 3)
board = cv.aruco.CharucoBoard(board_size, 1.0, .8, aruco_dict)
charuco_detector = cv.aruco.CharucoDetector(board)
cell_size = 120
image = board.generateImage((cell_size*board_size[0], cell_size*board_size[1]))
# Note: Expected values adjusted by -0.5px after fixing the systematic offset bug in charuco_detector.cpp
# The fix removes the incorrect +0.5 offset that was added after cornerSubPix
list_gold_corners = [(cell_size - 0.5, cell_size - 0.5), (2*cell_size - 0.5, cell_size - 0.5),
(2*cell_size - 0.5, 2*cell_size - 0.5), (cell_size - 0.5, 2*cell_size - 0.5)]
gold_corners = np.array(list_gold_corners, dtype=np.float32)
diamond_corners, diamond_ids, marker_corners, marker_ids = charuco_detector.detectDiamonds(image)
self.assertEqual(diamond_ids.size, 4)
self.assertEqual(marker_ids.size, 4)
for i in range(0, 4):
self.assertEqual(diamond_ids[0][0][i], i)
np.testing.assert_allclose(gold_corners, np.array(diamond_corners, dtype=np.float32).reshape(-1, 2), 0.01, 0.1)
# check no segfault when cameraMatrix or distCoeffs are not initialized
def test_charuco_no_segfault_params(self):
dictionary = cv.aruco.getPredefinedDictionary(cv.aruco.DICT_4X4_1000)
board = cv.aruco.CharucoBoard((10, 10), 0.019, 0.015, dictionary)
charuco_parameters = cv.aruco.CharucoParameters()
detector = cv.aruco.CharucoDetector(board)
detector.setCharucoParameters(charuco_parameters)
self.assertIsNone(detector.getCharucoParameters().cameraMatrix)
self.assertIsNone(detector.getCharucoParameters().distCoeffs)
def test_charuco_no_segfault_params_constructor(self):
dictionary = cv.aruco.getPredefinedDictionary(cv.aruco.DICT_4X4_1000)
board = cv.aruco.CharucoBoard((10, 10), 0.019, 0.015, dictionary)
charuco_parameters = cv.aruco.CharucoParameters()
detector = cv.aruco.CharucoDetector(board, charucoParams=charuco_parameters)
self.assertIsNone(detector.getCharucoParameters().cameraMatrix)
self.assertIsNone(detector.getCharucoParameters().distCoeffs)
# similar to C++ test CV_CharucoDetection.accuracy
def test_charuco_detector_accuracy(self):
iteration = 0
cameraMatrix = np.eye(3, 3, dtype=np.float64)
imgSize = (500, 500)
params = cv.aruco.DetectorParameters()
params.minDistanceToBorder = 3
board = cv.aruco.CharucoBoard((4, 4), 0.03, 0.015, cv.aruco.getPredefinedDictionary(cv.aruco.DICT_6X6_250))
detector = cv.aruco.CharucoDetector(board, detectorParams=params)
cameraMatrix[0, 0] = cameraMatrix[1, 1] = 600
cameraMatrix[0, 2] = imgSize[0] / 2
cameraMatrix[1, 2] = imgSize[1] / 2
# for different perspectives
distCoeffs = np.zeros((5, 1), dtype=np.float64)
for distance in [0.2, 0.4]:
for yaw in range(-55, 51, 25):
for pitch in range(-55, 51, 25):
markerBorder = iteration % 2 + 1
iteration += 1
# create synthetic image
img, rvec, tvec = projectCharucoBoard(board, cameraMatrix, yaw * pi / 180, pitch * pi / 180, distance, imgSize, markerBorder)
params.markerBorderBits = markerBorder
detector.setDetectorParameters(params)
if (iteration % 2 != 0):
charucoParameters = cv.aruco.CharucoParameters()
charucoParameters.cameraMatrix = cameraMatrix
charucoParameters.distCoeffs = distCoeffs
detector.setCharucoParameters(charucoParameters)
charucoCorners, charucoIds, corners, ids = detector.detectBoard(img)
self.assertGreater(len(ids), 0)
copyChessboardCorners = board.getChessboardCorners()
copyChessboardCorners -= np.array(board.getRightBottomCorner()) / 2
projectedCharucoCorners, _ = cv.projectPoints(copyChessboardCorners, rvec, tvec, cameraMatrix, distCoeffs)
if charucoIds is None:
# Detection can fail at extreme viewing angles
self.assertTrue(abs(yaw) >= 45 or abs(pitch) >= 45,
f"Detection failed unexpectedly at yaw={yaw}, pitch={pitch}")
continue
for i in range(len(charucoIds)):
currentId = charucoIds[i]
self.assertLess(currentId, len(board.getChessboardCorners()))
reprErr = cv.norm(charucoCorners[i] - projectedCharucoCorners[currentId])
self.assertLessEqual(reprErr, 5)
def test_aruco_match_image_points(self):
aruco_dict = cv.aruco.getPredefinedDictionary(cv.aruco.DICT_4X4_50)
board_size = (3, 4)
board = cv.aruco.GridBoard(board_size, 5.0, 1.0, aruco_dict)
aruco_corners = np.array(board.getObjPoints())[:, :, :2]
aruco_ids = board.getIds()
obj_points, img_points = board.matchImagePoints(aruco_corners, aruco_ids)
aruco_corners = aruco_corners.reshape(-1, 2)
self.assertEqual(aruco_corners.shape[0], obj_points.shape[0])
self.assertEqual(img_points.shape[0], obj_points.shape[0])
self.assertEqual(2, img_points.shape[2])
np.testing.assert_array_equal(aruco_corners, obj_points[:, :, :2].reshape(-1, 2))
def test_charuco_match_image_points(self):
aruco_dict = cv.aruco.getPredefinedDictionary(cv.aruco.DICT_4X4_50)
board_size = (3, 4)
board = cv.aruco.CharucoBoard(board_size, 5.0, 1.0, aruco_dict)
chessboard_corners = np.array(board.getChessboardCorners())[:, :2]
chessboard_ids = board.getIds()
obj_points, img_points = board.matchImagePoints(chessboard_corners, chessboard_ids)
self.assertEqual(chessboard_corners.shape[0], obj_points.shape[0])
self.assertEqual(img_points.shape[0], obj_points.shape[0])
self.assertEqual(2, img_points.shape[2])
np.testing.assert_array_equal(chessboard_corners, obj_points[:, :, :2].reshape(-1, 2))
def test_draw_detected_markers(self):
detected_points = [[[10, 10], [50, 10], [50, 50], [10, 50]]]
img = np.zeros((60, 60), dtype=np.uint8)
# add extra dimension in Python to create Nx4 Mat with 2 channels
points1 = np.array(detected_points).reshape(-1, 4, 1, 2)
img = cv.aruco.drawDetectedMarkers(img, points1, borderColor=255)
# check that the marker borders are painted
contours, _ = cv.findContours(img, cv.RETR_EXTERNAL, cv.CHAIN_APPROX_SIMPLE)
self.assertEqual(len(contours), 1)
self.assertEqual(img[10, 10], 255)
self.assertEqual(img[50, 10], 255)
self.assertEqual(img[50, 50], 255)
self.assertEqual(img[10, 50], 255)
# must throw Exception without extra dimension
points2 = np.array(detected_points)
with self.assertRaises(Exception):
img = cv.aruco.drawDetectedMarkers(img, points2, borderColor=255)
def test_draw_detected_charuco(self):
detected_points = [[[10, 10], [50, 10], [50, 50], [10, 50]]]
img = np.zeros((60, 60), dtype=np.uint8)
# add extra dimension in Python to create Nx1 Mat with 2 channels
points = np.array(detected_points).reshape(-1, 1, 2)
img = cv.aruco.drawDetectedCornersCharuco(img, points, cornerColor=255)
# check that the 4 charuco corners are painted
contours, _ = cv.findContours(img, cv.RETR_EXTERNAL, cv.CHAIN_APPROX_SIMPLE)
self.assertEqual(len(contours), 4)
for contour in contours:
center_x = round(np.average(contour[:, 0, 0]))
center_y = round(np.average(contour[:, 0, 1]))
center = [center_x, center_y]
self.assertTrue(center in detected_points[0])
# must throw Exception without extra dimension
points2 = np.array(detected_points)
with self.assertRaises(Exception):
img = cv.aruco.drawDetectedCornersCharuco(img, points2, borderColor=255)
def test_draw_detected_diamonds(self):
detected_points = [[[10, 10], [50, 10], [50, 50], [10, 50]]]
img = np.zeros((60, 60), dtype=np.uint8)
# add extra dimension in Python to create Nx4 Mat with 2 channels
points = np.array(detected_points).reshape(-1, 4, 1, 2)
img = cv.aruco.drawDetectedDiamonds(img, points, borderColor=255)
# check that the diamonds borders are painted
contours, _ = cv.findContours(img, cv.RETR_EXTERNAL, cv.CHAIN_APPROX_SIMPLE)
self.assertEqual(len(contours), 1)
self.assertEqual(img[10, 10], 255)
self.assertEqual(img[50, 10], 255)
self.assertEqual(img[50, 50], 255)
self.assertEqual(img[10, 50], 255)
# must throw Exception without extra dimension
points2 = np.array(detected_points)
with self.assertRaises(Exception):
img = cv.aruco.drawDetectedDiamonds(img, points2, borderColor=255)
def test_multi_dict_arucodetector(self):
aruco_params = cv.aruco.DetectorParameters()
aruco_dicts = [
cv.aruco.getPredefinedDictionary(cv.aruco.DICT_4X4_250),
cv.aruco.getPredefinedDictionary(cv.aruco.DICT_5X5_250)
]
aruco_detector = cv.aruco.ArucoDetector(aruco_dicts, aruco_params)
id = 2
marker_size = 100
offset = 10
img_marker1 = cv.aruco.generateImageMarker(aruco_dicts[0], id, marker_size, aruco_params.markerBorderBits)
img_marker1 = np.pad(img_marker1, pad_width=offset, mode='constant', constant_values=255)
img_marker2 = cv.aruco.generateImageMarker(aruco_dicts[1], id, marker_size, aruco_params.markerBorderBits)
img_marker2 = np.pad(img_marker2, pad_width=offset, mode='constant', constant_values=255)
img_markers = np.concatenate((img_marker1, img_marker2), axis=1)
corners, ids, rejected, dictIndices = aruco_detector.detectMarkersMultiDict(img_markers)
self.assertEqual(2, len(ids))
self.assertEqual(id, ids[0])
self.assertEqual(id, ids[1])
self.assertEqual(2, len(dictIndices))
self.assertEqual(0, dictIndices[0])
self.assertEqual(1, dictIndices[1])
if __name__ == '__main__':
NewOpenCVTests.bootstrap()