def MVP_from_P()

in lib/render/camera.py [0:0]

• 33 lines of code
• 1 McCabe index (conditional complexity)

def MVP_from_P(proj_mat, width, height, near=0.1, far=10000):
    '''
    Convert OpenCV camera calibration matrix to OpenGL projection and model view matrix
    :param proj_mat: OpenCV camera projeciton matrix
    :param width: Image width
    :param height: Image height
    :param near: Z near value
    :param far: Z far value
    :return: OpenGL projection matrix and model view matrix
    '''
    res = cv2.decomposeProjectionMatrix(proj_mat)
    K, Rot, camera_center_homog = res[0], res[1], res[2]
    camera_center = camera_center_homog[0:3] / camera_center_homog[3]
    trans = -Rot.dot(camera_center)
    K = K / K[2][2]

    extrinsic = np.eye(4)
    extrinsic[:3, :3] = Rot
    extrinsic[:3, 3:4] = trans
    axis_adj = np.eye(4)
    axis_adj[2, 2] = -1
    axis_adj[1, 1] = -1
    model_view = np.matmul(axis_adj, extrinsic)

    zFar = far
    zNear = near
    projective = np.zeros([4, 4])
    projective[:2, :2] = K[:2, :2]
    projective[:2, 2:3] = -K[:2, 2:3]
    projective[3, 2] = -1
    projective[2, 2] = (zNear + zFar)
    projective[2, 3] = (zNear * zFar)

    ndc = ortho(0, width, 0, height, zNear, zFar)

    perspective = np.matmul(ndc, projective)

    return perspective, model_view