calib.py

import os

import cv2
import numpy as np
import glob
import pickle as pkl

# Defining the dimensions of checkerboard
CHECKERBOARD = (7, 7)
criteria = (cv2.TERM_CRITERIA_EPS + cv2.TERM_CRITERIA_MAX_ITER, 30, 0.001)

# Creating vector to store vectors of 3D points for each checkerboard image
objpoints = []
# Creating vector to store vectors of 2D points for each checkerboard image
imgpoints = []


# Defining the world coordinates for 3D points
objp = np.zeros((1, CHECKERBOARD[0] * CHECKERBOARD[1], 3), np.float32)
objp[0, :, :2] = np.mgrid[0:CHECKERBOARD[0], 0:CHECKERBOARD[1]].T.reshape(-1, 2)
prev_img_shape = None

# Extracting path of individual image stored in a given directory
images = glob.glob("images/calib/*")[:80]
for fname in images:
    img = cv2.imread(fname)
    gray = cv2.cvtColor(img, cv2.COLOR_BGR2GRAY)
    # Find the chess board corners
    # If desired number of corners are found in the image then ret = true
    ret, corners = cv2.findChessboardCorners(gray, CHECKERBOARD, cv2.CALIB_CB_ADAPTIVE_THRESH + cv2.CALIB_CB_FAST_CHECK + cv2.CALIB_CB_NORMALIZE_IMAGE)

    """
    If desired number of corner are detected,
    we refine the pixel coordinates and display 
    them on the images of checker board
    """
    if ret:
        print(".", end="")
        objpoints.append(objp)
        # refining pixel coordinates for given 2d points.
        corners2 = cv2.cornerSubPix(gray, corners, (11, 11), (-1, -1), criteria)

        imgpoints.append(corners2)

        # # Draw and display the corners
        # img = cv2.drawChessboardCorners(img, CHECKERBOARD, corners2, ret)
    else:
        print("x", end="")

    # cv2.imshow('img', img)
    # cv2.waitKey(0)

# cv2.destroyAllWindows()

h, w = img.shape[:2]

"""
Performing camera calibration by 
passing the value of known 3D points (objpoints)
and corresponding pixel coordinates of the 
detected corners (imgpoints)
"""
ret, mtx, dist, rvecs, tvecs = cv2.calibrateCamera(objpoints, imgpoints, gray.shape[::-1], None, None)

print("Camera matrix : \n")
print(mtx)
print("dist : \n")
print(dist)

if os.path.exists("calib"):
    os.remove("calib")

with open("calib", "xb") as f:
    pkl.dump((mtx, dist), f)

# print("rvecs : \n")
# print(rvecs)
# print("tvecs : \n")
# print(tvecs)