I am trying to estimate the 3D Pose of an object using solvePnP in python.
But the problem is even if I kept both the camera and object static, the output of solvePnP (rvec and tvec) are changing. The world coordinates system is centered on the object and moves along with it. I am passing 4 image points and the corresponding 4 object points.
Calling SolvePnP:
retval, rvec, tvec = cv2.solvePnP(cam.object_points, cam.image_points, cam.camera_matrix, cam.dist_coefficients, None, None, False, cv2.SOLVEPNP_ITERATIVE)
Output 1:
Image points:
[[ 236. 243.]
[ 43. 368.]
[ 404. 372.]
[ 235. 357.]]
Object points:
[[ 0. 0. 0. ]
[ 6.5 0. 0. ]
[ 0. 0. 6.5]
[ 0. 6.5 0. ]]
R VECT==========
[[-0.56619693]
[-2.27732794]
[ 0.71053527]]
T VECT==========
[[ 0.54725923]
[-0.45834745]
[ 0.58522831]]
Output 2:
Image points:
[[ 236. 243.]
[ 43. 369.]
[ 404. 372.]
[ 235. 357.]]
Object points:
[[ 0. 0. 0. ]
[ 6.5 0. 0. ]
[ 0. 0. 6.5]
[ 0. 6.5 0. ]]
R VECT==========
[[ 0.33325838]
[ 2.12767845]
[ 0.98248134]]
T VECT==========
[[ -2.60687131]
[ 0.37989386]
[ 23.85078678]]
The object points and image points are identical but solvePnP still gives several different results. The above results are alternating one after another for alternative frames.
How should I resolve it?