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about matrix expansion with python opencv

I am trying to find the Euler angle from the rotation matrix using OpenCV in python.
I am trying to get Euler angle using decomposeProjectionMatrix (),
I need a rotation matrix that is a 3x3 matrix, but I don't know how to extend it to a 3x4 matrix.

double * _r = rotCamerMatrix.ptr();
double projMatrix [12] = {_r [0], _ r [1], _ r [2], 0, _r [3], _ r [4], _ r [5], 0, _r [6], _ r [7] , _r [8], 0};
projMat = cv :: Mat (3,4, CV_64FC1, projMatrix);

C ++ looks like this, but I don't know how to implement it in python.

Thanks for your professor.

Reference URL (FW/tool version etc.)

Reference : https://qiita.com/TaroYamada/items/e3f3d0ea4ecc0a832fac

python python3.x opencv
  • Answer # 1

    I think that it is better to use the numpy.insert function for matrix expansion.

    import numpy as np
a = np.array ([[0,1,2], [3,4,5], [6,7,8]]);
print (a)
# [[0 1 2]
# [3 4 5]
# [6 7 8]]
b = np.insert (a, 3,0, axis = 1)
print (b)
# [[0 1 2 0]
# [3 4 5 0]
# [6 7 8 0]]

    This article is helpful.

    How to use insert to insert/add elements/rows/columns to NumPy array ndarray

    I hope you find it helpful.

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