Creating numpy array from ctypes POINTER using ctypes.memmove() gives wrong results

Question

I am using ctypes to call a C++ function and calculate homography. Then it was converted into a numpy array. The homography printed in C++ is correct. However, in python it's totally wrong after converting to numpy array using ctypes.memmove().

For examply, in C++ the homography is:

[[0.999931, 3.05449e-06, 0.0219359],

[-3.46952e-05, 1.00004, 0.0162477],

[-1.20569e-08, -6.80167e-09, 1]]

In Python, the trs_matrix (homography) is:

[[ 3.36311631e-44, 0.00000000e+00, 2.25339716e+12]

[ 4.59163468e-41,2.25339612e+12, 4.59163468e-41]

[ 2.25339821e+12,4.59163468e-41, 2.24207754e-44]]

Python Code:

def find_homo(self, numLoops=1000, minScore=0.85, maxAmbiguity=0.95, thresh=5.0):

    homography = ctypes.POINTER(ctypes.c_float)()

    num_match = _LIB.FindHomography_C(
        ctypes.byref(self),
        ctypes.byref(homography),
        ctypes.c_int(numLoops),
        ctypes.c_float(minScore),
        ctypes.c_float(maxAmbiguity),
        ctypes.c_float(thresh)
    )
    
    trs_matrix = ctypes2numpy(homography, 9, np.float32).reshape((3, 3))

    return trs_matrix, num_match


def ctypes2numpy(cptr, length, dtype):
    #Convert a ctypes pointer array to a numpy array
    
    if not isinstance(cptr, ctypes.POINTER(ctypes.c_float)):
        raise RuntimeError('Expected float pointer')

    res = np.zeros(length, dtype=dtype)
    
    if not ctypes.memmove(res.ctypes.data, cptr, length * res.strides[0]):
        raise RuntimeError('memmove failed')

    return res

C++ Code:

int FindHomography_C(SiftData &data, float** out_homo, int numLoops, float minScore, float maxAmbiguity, float thresh){
    //API_BEGIN();
    int numMatches = 0;

    float homography[9];

    FindHomography(data, homography,  &numMatches, numLoops, minScore, maxAmbiguity, thresh);

    *out_homo = &homography[0];

    return numMatches;
}