# Projection matrix

Hello I have one question.

I am using drone and I have his location (x,y,z and rotation) so use this function to calculate projection matrix.

``````def projection_matrix(x, y, z, theta, K):

R_x = np.array([[1, 0, 0],
[0, np.cos(theta[0]), -np.sin(theta[0])],
[0, np.sin(theta[0]), np.cos(theta[0])]
])

R_y = np.array([[np.cos(theta[1]), 0, np.sin(theta[1])],
[0, 1, 0],
[-np.sin(theta[1]), 0, np.cos(theta[1])]
])

R_z = np.array([[np.cos(theta[2]), -np.sin(theta[2]), 0],
[np.sin(theta[2]), np.cos(theta[2]), 0],
[0, 0, 1]
])

R = np.dot(R_z, np.dot(R_y, R_x))
t = np.array([x, y, z])

C = np.dot(-np.matrix.transpose(R),t)
R_C = np.matrix.transpose(R)

Rt = np.zeros((3, 4))
Rt[:3, :3] = R_C
Rt[:3, 3] = C

P = np.dot(K, Rt)

return P

P1 = projection_matrix(x=x, y=z, z=y, theta=[0, -theta, 0], K=K)
P0 = projection_matrix(x=0, y=0, z=0, theta=[0, 0, 0], K=K)
``````

I used transpose matrix beacuse I was told that camera pose is difrent then world coordinate system. And I used this equations to transform them:

I donâ€™t know if I am doing this correct beacuse I get off results when I triangulate 2D points with this 2 projection matrix

related:

as for pose matrices, you should browse this forum. many people have written a lot about this.

this tag contains those discussions:

https://forum.opencv.org/tag/calib3d