c++opencvcamera-calibration
Hand To Eye Calibration
I want to do Hand-To-Eye calibration to get the pose of external fixed camera compared to the base of the robot using calibrateRobotWorldHandEye
However most of the code examples (including OpenCV docs) are explaining Hand-in-Eye calibration.
to do so I do the following:
cv::calibrateRobotWorldHandEye(
r_marker_2_cams, t_marker_2_cams,
r_base_2_eefs, t_base_2_eefs,
r_base_2_marker, t_base_2_marker,
r_eef_2_cam, t_eef_2_cam
);
However the transform that I want is from camera to the base r_cam_2_base, t_cam_2_base but I'm not sure how I can do that as I didn't find any example.
the values of the base_2_eefs, marker_2_cams vectors are the following:
{
"0" :
{
"eef_to_base" :
{
"rotation" :
[
[
-0.095606111055037801,
-0.51025118851622564,
-0.85469479707478668
],
[
-0.2832817770222838,
-0.80917743832918987,
0.51476529419348682
],
[
-0.95425934961939407,
0.29133416881098761,
-0.067182555378477338
]
],
"translation" :
[
0.90001126059008763,
0.26805892340487769,
0.98525793586232102
]
},
"marker_to_camera" :
{
"rotation" :
[
[
0.92253465633644494,
-0.2152414766107825,
0.32031377523392118
],
[
-0.2152414766107825,
-0.97590218043617782,
-0.035861413334157398
],
[
0.32031377523392118,
-0.035861413334157398,
-0.94663247590026744
]
],
"translation" :
[
0.03402884930726869,
0.014143468196645812,
0.15751829284878796
]
}
},
"1" :
{
"eef_to_base" :
{
"rotation" :
[
[
-0.20698015831412614,
-0.61227580911613599,
-0.76307112881791062
],
[
-0.41541975402669973,
-0.65115455185373627,
0.6351568133654526
],
[
-0.88576839073691027,
0.44845967842308965,
-0.11957539378987342
]
],
"translation" :
[
0.96772548551068494,
0.19639468634609225,
0.89220657837415496
]
},
"marker_to_camera" :
{
"rotation" :
[
[
0.95787953058770325,
-0.23867817485777876,
0.15968573426465274
],
[
-0.23867817485777876,
-0.97090358713932667,
-0.019466723569897548
],
[
0.15968573426465274,
-0.019466723569897548,
-0.98697594344837614
]
],
"translation" :
[
0.044783191711068503,
0.023470920523726766,
0.15747101277574513
]
}
},
"2" :
{
"eef_to_base" :
{
"rotation" :
[
[
-0.12350759604901118,
-0.20680972023673849,
-0.97055428149784384
],
[
-0.18232558826984002,
-0.95666344874673281,
0.22705159258209323
],
[
-0.97545028247484278,
0.20499947670082008,
0.080448498880580921
]
],
"translation" :
[
0.73249608671719035,
0.66220009961098181,
0.89221177149030129
]
},
"marker_to_camera" :
{
"rotation" :
[
[
0.78348037242671398,
-0.11539983601306734,
0.61060738930204139
],
[
-0.11539983601306734,
-0.99253307053011008,
-0.039509261600644968
],
[
0.61060738930204139,
-0.039509261600644968,
-0.79094730189660378
]
],
"translation" :
[
-0.021747313435247093,
0.026637357656369078,
0.1910133070186012
]
}
},
"3" :
{
"eef_to_base" :
{
"rotation" :
[
[
-0.14139277743876,
-0.58163823962076944,
-0.80106494162396458
],
[
-0.066538421728242203,
-0.80178083087220542,
0.59390246478676123
],
[
-0.98771489860286521,
0.13727511594141062,
0.074664728093018773
]
],
"translation" :
[
0.91470660231510692,
0.28704308433655318,
0.9501287577881915
]
},
"marker_to_camera" :
{
"rotation" :
[
[
0.95967525014499111,
-0.063827726844024352,
0.27376894554546011
],
[
-0.063827726844024352,
-0.99792109498052117,
-0.0089168087790869148
],
[
0.27376894554546011,
-0.0089168087790869148,
-0.96175415516447016
]
],
"translation" :
[
0.026701151449500173,
0.023098944615863572,
0.16560896248519821
]
}
},
"4" :
{
"eef_to_base" :
{
"rotation" :
[
[
-0.15445547258729375,
-0.78526027945890686,
-0.59959136125527657
],
[
-0.023678306619458522,
-0.6037576161025463,
0.79681621393757118
],
[
-0.98771597374117148,
0.13726993298712675,
0.074660034250187302
]
],
"translation" :
[
0.95856056973329129,
0.015659241202002405,
0.95013413396721758
]
},
"marker_to_camera" :
{
"rotation" :
[
[
0.99915164331289708,
-0.033625485075008531,
-0.02377646774876508
],
[
-0.033625485075008531,
-0.99943442347142009,
0.00039991726695511552
],
[
-0.02377646774876508,
0.00039991726695511552,
-0.99971721984147655
]
],
"translation" :
[
0.052542209909467959,
0.026759669926727965,
0.14180080527811537
]
}
}
}
But when I call the calibration function I get and error:
lib/opencv-4.5.2/modules/calib3d/src/calibration_handeye.cpp:524:
error: (-7:Iterations do not converge) Rotation normalization issue: determinant(R) is null in function 'normalizeRotation
Can you please tell me if my approach in computing Hand-To-Eye calibration is wrong, and how can I fix it? thanks
Solution
for hand-to-eye calibration my approach was wrong, we need to compute T_cam2base:
cv::calibrateRobotWorldHandEye(
r_marker_2_cams, t_marker_2_cams,
r_eefs_2_base, t_eefs_2_base,
r_base_2_marker, t_base_2_marker,
r_base_2_cam, t_base_2_cam
);