相机坐标系与图像的投影

import cv2 as cv
import numpy as np
import glob
from _gs_ import stereo_camera

def draw(img, corners, imgpts):

    corner = tuple(corners[0].ravel())
    img = cv.line(img, np.int32(corner), np.int32((imgpts[0].ravel())), (255,0,0), 5)
    img = cv.line(img, np.int32(corner), np.int32((imgpts[1].ravel())), (0,255,0), 5)
    img = cv.line(img, np.int32(corner), np.int32((imgpts[2].ravel())), (0,0,255), 5)
    return img


def draw2(img, corners, imgpts):

  imgpts = np.int32(imgpts).reshape(-1, 2)
  print('imgpts: ', imgpts)

  # draw ground floor in green
  img = cv.drawContours(img, [imgpts[:4]], -1, (0, 255, 0), -3)

  # draw pillars in blue color
  for i, j in zip(range(4), range(4, 8)):

    img = cv.line(img, tuple(imgpts[i]), tuple(imgpts[j]), (0,0,255), 3)

  # draw top layer in red color
  img = cv.drawContours(img, [imgpts[4:]], -1, (0, 0, 255), 3)

  return img

criteria = (cv.TERM_CRITERIA_EPS + cv.TERM_CRITERIA_MAX_ITER, 30, 0.001)
objp = np.zeros((6*7,3), np.float32)
objp[:,:2] = np.mgrid[0:7,0:6].T.reshape(-1,2)

# axis = np.float32([[3,0,0], [0,3,0], [0,0,-3]]).reshape(-1,3)
axis = np.float32([[0,0,0], [0,3,0], [3,3,0], [3,0,0],
                   [0,0,-3],[0,3,-3],[3,3,-3],[3,0,-3] ])

for fname in glob.glob('D:/mydocs/git_src/TScanSoftware/data/out/img_000*.jpg'):
    img = cv.imread(fname)
    gray = cv.cvtColor(img,cv.COLOR_BGR2GRAY)
    ret, corners = cv.findChessboardCorners(gray, (7,6),None)

    if ret == True:
        corners2 = cv.cornerSubPix(gray,corners,(11,11),(-1,-1),criteria)

        # Find the rotation and translation vectors.
        ret,rvecs, tvecs = cv.solvePnP(objp, corners2, stereo_camera.m1, stereo_camera.d1)

        # project 3D points to image plane
        imgpts, jac = cv.projectPoints(axis, rvecs, tvecs, stereo_camera.m1, stereo_camera.d1)
        img = draw2(img,corners2,imgpts)
        cv.imshow('img',img)
        k = cv.waitKey(0) & 0xFF
        if k == ord('s'):
            cv.imwrite(fname[:6]+'.png', img)

cv.destroyAllWindows()

7.2. 姿势估计 - OpenCV Python Tutorials (opencv-python-tutorials.readthedocs.io)