2020-01-15 12:45:03 -0500 received badge ● Notable Question (source) 2019-05-02 03:05:10 -0500 received badge ● Popular Question (source) 2017-12-12 07:51:38 -0500 marked best answer projectPoints tvec and rvec I have a problem understanding the two parameters of this function. I thought they are the translation and rotation of the camera in global coordinate system and object points are also given in this global coordinate system. But a simple test proves me wrong: import cv2 import numpy as np # principal point (60, 60) cammat = np.array([[30, 0, 60], [0, 30, 60], [0, 0, 1]], dtype=np.float32) distortion = np.array([0, 0, 0, 0, 0], dtype=np.float32) tvec = np.array([0, 0, 0], dtype=np.float32) rvec = np.array([0, 0, 0], dtype=np.float32) point_3d = np.array([0.1, 0.1, 1], dtype=np.float32) # [63.00, 63.00] p1 = cv2.projectPoints(np.array([[point_3d]]), rvec, tvec, cammat, distortion) # move camera a bit closer to the 3d point, expecting point on 2d plant # to be a bit further away from the principal point tvec = np.array([0, 0, 0.1], dtype=np.float32) # [62.72, 62.72] p2 = cv2.projectPoints(np.array([[point_3d]]), rvec, tvec, cammat, distortion)  Where am I wrong? 2017-12-12 07:51:38 -0500 received badge ● Scholar (source) 2017-12-12 07:51:37 -0500 received badge ● Supporter (source) 2017-12-05 03:36:27 -0500 received badge ● Necromancer (source) 2017-12-04 15:58:54 -0500 answered a question openCV and Pypy? As of Pypy 5.9, OpenCV just works. Instructions for usage in virtual environment: make virtual environment with virtua 2017-11-22 07:57:51 -0500 asked a question projectPoints tvec and rvec projectPoints tvec and rvec I have a problem understanding the two parameters of this function. I thought they are the t