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StereoCalibratePointCloud.py
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StereoCalibratePointCloud.py
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import numpy as np
import cv2 as cv
import glob
from matplotlib import pyplot as plt
################ FIND CHESSBOARD CORNERS - OBJECT POINTS AND IMAGE POINTS #############################
chessboardSize = (9,6)
frameSize = (640,480)
# termination criteria
criteria = (cv.TERM_CRITERIA_EPS + cv.TERM_CRITERIA_MAX_ITER, 30, 0.001)
# prepare object points, like (0,0,0), (1,0,0), (2,0,0) ....,(6,5,0)
objp = np.zeros((chessboardSize[0] * chessboardSize[1], 3), np.float32)
objp[:,:2] = np.mgrid[0:chessboardSize[0],0:chessboardSize[1]].T.reshape(-1,2)
objp = objp * 20
#print(objp)
# Arrays to store object points and image points from all the images.
objpoints = [] # 3d point in real world space
imgpointsL = [] # 2d points in image plane.
imgpointsR = [] # 2d points in image plane.
imagesLeft = sorted(glob.glob('images/left/*.png'))
imagesRight = sorted(glob.glob('images/right/*.png'))
for imgLeft, imgRight in zip(imagesLeft, imagesRight):
imgL = cv.imread(imgLeft)
imgR = cv.imread(imgRight)
grayL = cv.cvtColor(imgL, cv.COLOR_BGR2GRAY)
grayR = cv.cvtColor(imgR, cv.COLOR_BGR2GRAY)
# Find the chess board corners
retL, cornersL = cv.findChessboardCorners(grayL, chessboardSize, None)
retR, cornersR = cv.findChessboardCorners(grayR, chessboardSize, None)
# If found, add object points, image points (after refining them)
if retL and retR == True:
objpoints.append(objp)
cornersL = cv.cornerSubPix(grayL, cornersL, (11,11), (-1,-1), criteria)
imgpointsL.append(cornersL)
cornersR = cv.cornerSubPix(grayR, cornersR, (11,11), (-1,-1), criteria)
imgpointsR.append(cornersR)
# Draw and display the corners
cv.drawChessboardCorners(imgL, chessboardSize, cornersL, retL)
cv.imshow('img left', imgL)
cv.drawChessboardCorners(imgR, chessboardSize, cornersR, retR)
cv.imshow('img right', imgR)
cv.waitKey(100)
cv.destroyAllWindows()
############## CALIBRATION #######################################################
retL, cameraMatrixL, distL, rvecsL, tvecsL = cv.calibrateCamera(objpoints, imgpointsL, frameSize, None, None)
heightL, widthL, channelsL = imgL.shape
newCameraMatrixL, roi_L = cv.getOptimalNewCameraMatrix(cameraMatrixL, distL, (widthL, heightL), 1, (widthL, heightL))
retR, cameraMatrixR, distR, rvecsR, tvecsR = cv.calibrateCamera(objpoints, imgpointsR, frameSize, None, None)
heightR, widthR, channelsR = imgR.shape
newCameraMatrixR, roi_R = cv.getOptimalNewCameraMatrix(cameraMatrixR, distR, (widthR, heightR), 1, (widthR, heightR))
print(cameraMatrixL)
print(newCameraMatrixL)
########## Stereo Vision Calibration #############################################
flags = 0
flags |= cv.CALIB_FIX_INTRINSIC
# Here we fix the intrinsic camara matrixes so that only Rot, Trns, Emat and Fmat are calculated.
# Hence intrinsic parameters are the same
criteria_stereo = (cv.TERM_CRITERIA_EPS + cv.TERM_CRITERIA_MAX_ITER, 30, 0.001)
# This step is performed to transformation between the two cameras and calculate Essential and Fundamenatl matrix
retStereo, newCameraMatrixL, distL, newCameraMatrixR, distR, rot, trans, essentialMatrix, fundamentalMatrix = cv.stereoCalibrate(objpoints, imgpointsL, imgpointsR, newCameraMatrixL, distL, newCameraMatrixR, distR, grayL.shape[::-1], criteria_stereo, flags)
# Reprojection Error
mean_error = 0
for i in range(len(objpoints)):
imgpoints2, _ = cv.projectPoints(objpoints[i], rvecsL[i], tvecsL[i], newCameraMatrixL, distL)
error = cv.norm(imgpointsL[i], imgpoints2, cv.NORM_L2)/len(imgpoints2)
mean_error += error
print("total error: {}".format(mean_error/len(objpoints)))
########## Stereo Rectification #################################################
rectifyScale= 1
rectL, rectR, projMatrixL, projMatrixR, Q, roi_L, roi_R= cv.stereoRectify(newCameraMatrixL, distL, newCameraMatrixR, distR, grayL.shape[::-1], rot, trans, rectifyScale,(0,0))
print(Q)
stereoMapL = cv.initUndistortRectifyMap(newCameraMatrixL, distL, rectL, projMatrixL, grayL.shape[::-1], cv.CV_16SC2)
stereoMapR = cv.initUndistortRectifyMap(newCameraMatrixR, distR, rectR, projMatrixR, grayR.shape[::-1], cv.CV_16SC2)
print("Saving parameters!")
cv_file = cv.FileStorage('stereoMap.xml', cv.FILE_STORAGE_WRITE)
cv_file.write('stereoMapL_x',stereoMapL[0])
cv_file.write('stereoMapL_y',stereoMapL[1])
cv_file.write('stereoMapR_x',stereoMapR[0])
cv_file.write('stereoMapR_y',stereoMapR[1])
cv_file.write('q', Q)
cv_file.release()