Interpretation of projectPoints() function

问题

I am working on converting 3D real-world points (X,Y,Z) meters to image coordinates (u, v) pixels. I have access to the Camera matrix K, camera orientation (in degrees) and translation vector.

I use the code below to calculate the pixel coordinates. For (X,Y,Z) = (0.04379281, 0.15902013, 0.73328906), I obtain (u, v) = (-184.52735432, -249.19158505) on an image of size 352x287 px. Is the origin of pixel coordinates in the image still top left corner? If yes, the obtained pixel location is outside the image. Is this right?

# Calculates Rotation Matrix given euler angles.
def eulerAnglesToRotationMatrix(theta):
R_x = np.array([[1, 0, 0],
            [0, math.cos(theta[0]), -math.sin(theta[0])],
            [0, math.sin(theta[0]), math.cos(theta[0])]
            ])

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

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

R = np.dot(R_z, np.dot(R_y, R_x))
return R

# x-roll, y-pitch, z-yaw (in degrees)
theta = [-128.41639709472657, -11.528900146484375, 53.37379837036133]

# rotation vector
rvec = eulerAnglesToRotationMatrix(theta)
# translation vector
tvec = np.array([[0.26409998536109927], [1.294700026512146], 
[0.017799999564886094]], np.float)
# camera matrix
cameraMatrix = np.array([[148.130859375, 0, 142.5562286376953],
                [0, 148.130859375, 179.04293823242188],
                [0, 0, 1]], np.float)


# Point in (X,Y,Z) meters
objPts = np.array([[0.04379281, 0.15902013, 0.73328906]], np.float)

distCoeffs = np.array([0, 0, 0, 0, 0], np.float)

imgPts, _ = cv2.projectPoints(objPts, rvec, tvec, cameraMatrix, distCoeffs)

来源：https://stackoverflow.com/questions/51594411/interpretation-of-projectpoints-function

标签

python

OpenCV

cv2