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add python charuco sample#23139

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asmorkalov merged 1 commit intoopencv:4.xfrom
AleksandrPanov:add_py_charuco_sample
Mar 15, 2023
Merged

add python charuco sample#23139
asmorkalov merged 1 commit intoopencv:4.xfrom
AleksandrPanov:add_py_charuco_sample

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@AleksandrPanov AleksandrPanov commented Jan 15, 2023 •
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Added python sample to detect charuco board.

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  • I agree to contribute to the project under Apache 2 License.
  • 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
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    Patch to opencv_extra has the same branch name.
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AleksandrPanov commented Jan 15, 2023 •
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works with choriginal.jpg:
choriginal
tutorial_camera_charuco.yml.txt

args:
-w=5 -h=7 -sl=0.04 -ml=0.02 -d=10 -v=choriginal.jpg

result:
image

To correctly works with matchImagePoints need merge PR #23138

@AleksandrPanov AleksandrPanov marked this pull request as ready for review January 15, 2023 23:54
@AleksandrPanov AleksandrPanov mentioned this pull request Jan 15, 2023
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@asmorkalov asmorkalov self-requested a review January 16, 2023 09:03
@AleksandrPanov AleksandrPanov force-pushed the add_py_charuco_sample branch 2 times, most recently from 8d1006b to 3a5109d Compare January 16, 2023 18:25
@AleksandrPanov AleksandrPanov mentioned this pull request Jan 16, 2023
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satpalsr commented Jan 18, 2023 •
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Hey @AleksandrPanov , can you share how you generated charuco board? Specially want to fit on A4 paper size.

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AleksandrPanov commented Jan 18, 2023 •
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Hey @satpalsr, you can use code from this sample:

import cv2 as cv
from cv2 import aruco
print(cv.__version__)


"setup"
arucoDict = aruco.getPredefinedDictionary(aruco.DICT_6X6_250)

"create the charuco board"
calibration_board = aruco.CharucoBoard((5, 7), squareLength=0.072, markerLength=0.062, dictionary=arucoDict)
board_image = calibration_board.generateImage((500, 700))
cv.imwrite("sample_board.png", board_image)

asmorkalov
asmorkalov requested changes Jan 18, 2023
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@AleksandrPanov AleksandrPanov force-pushed the add_py_charuco_sample branch 2 times, most recently from f80907a to 0a649e5 Compare January 19, 2023 16:50
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asmorkalov commented Jan 20, 2023

Current version of sample fails with exception, when Charuco board is shown to camera:

[ WARN:0@1.571] global cap_gstreamer.cpp:1728 open OpenCV | GStreamer warning: Cannot query video position: status=0, value=-1, duration=-1
Traceback (most recent call last):
  File "./aruco_detect_board_charuco.py", line 110, in <module>
    main()
  File "./aruco_detect_board_charuco.py", line 95, in main
    if len(charuco_ids) > 0:
TypeError: object of type 'NoneType' has no len()

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AleksandrPanov commented Jan 20, 2023

add NoneType checks

Now sample must works in all cases:
part charuco corners:
image
full charuco corners:
image
and also works without charuco corners

(Uses PR #23138)

@AleksandrPanov AleksandrPanov marked this pull request as draft January 20, 2023 15:15
@AleksandrPanov AleksandrPanov marked this pull request as ready for review January 20, 2023 15:24
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AleksandrPanov commented Jan 20, 2023 •
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I check sample with camera and add new condition to correct work with solvePnP():
if len(cam_matrix) > 0 and len(charuco_ids) >= 4:

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satpalsr commented Jan 21, 2023

Also add if len(obj_points) >= 6:

Otherwise I get

    flag, rvec, tvec = cv.solvePnP(obj_points, img_points, cam_matrix, dist_coefficients)
cv2.error: OpenCV(4.7.0) /io/opencv/modules/calib3d/src/calibration.cpp:1173: error: (-2:Unspecified error) in function 'void cvFindExtrinsicCameraParams2(const CvMat*, const CvMat*, const CvMat*, const CvMat*, CvMat*, CvMat*, int)'
> DLT algorithm needs at least 6 points for pose estimation from 3D-2D point correspondences. (expected: 'count >= 6'), where
>     'count' is 4
> must be greater than or equal to
>     '6' is 6

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satpalsr commented Jan 21, 2023

Also, would be cool to add Charuco camera calibration script/function.

@asmorkalov asmorkalov mentioned this pull request Jan 25, 2023
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alalek
alalek reviewed Jan 25, 2023
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Please take a look on already maintained samples in the main repository.

@AleksandrPanov AleksandrPanov force-pushed the add_py_charuco_sample branch 2 times, most recently from e031712 to faa479d Compare January 27, 2023 00:53
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asmorkalov commented Feb 3, 2023

@alalek Could you take a look again? May the PR be merged?

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asmorkalov reviewed Feb 9, 2023
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alalek
alalek reviewed Feb 9, 2023
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@AleksandrPanov AleksandrPanov force-pushed the add_py_charuco_sample branch 2 times, most recently from f42d9db to 3960ca2 Compare March 13, 2023 12:07
@asmorkalov asmorkalov self-requested a review March 13, 2023 12:54
asmorkalov
asmorkalov reviewed Mar 13, 2023
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@AleksandrPanov AleksandrPanov force-pushed the add_py_charuco_sample branch from 3960ca2 to 0d455e0 Compare March 15, 2023 08:28
@asmorkalov asmorkalov added this to the 4.8.0 milestone Mar 15, 2023
@asmorkalov asmorkalov merged commit 86fa030 into opencv:4.x Mar 15, 2023
@asmorkalov asmorkalov mentioned this pull request May 31, 2023
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