Webcam Calibration Studio – Intelligent Vision Systems

mirror view straight-line grid

1 · Start the camera

Allow the browser to use your webcam. Hold the printed 9 × 6 chessboard (or a phone showing it) in front of it.

camera resolution

2 · Tell the computer about your board

Inner corners (where 4 squares meet): the course pattern has 9 × 6. Measure one square with a ruler.

corners across down square size (mm)

3 · Capture 15–20 good views

Green corners = board found. Auto takes a picture when the board is still and in a new place. Move it to the edges and corners, tilt it, near and far.

0 views captured.

4 · Calibrate

Runs cv2.calibrateCamera on your views (needs at least 8; 15+ is better).

rational model (very wide lenses)

RMS reprojection error:

Error of each view (click a bar to delete a bad view, then calibrate again).

5 · Use it

③ Undistort: see the corrected live image. ④ Measure: hold the board up and read its distance; check it with a ruler or tape measure.

alpha (0 = crop, 1 = keep all) 0 view

Show the Python (cv2) code this page runs

import cv2, numpy as np
nx, ny, square = 9, 6, 25.0                      # inner corners, mm
objp = np.zeros((nx * ny, 3), np.float32)
objp[:, :2] = np.mgrid[0:nx, 0:ny].T.reshape(-1, 2) * square

# live:   found, corners = cv2.findChessboardCorners(gray, (nx, ny),
#              cv2.CALIB_CB_ADAPTIVE_THRESH | cv2.CALIB_CB_NORMALIZE_IMAGE | cv2.CALIB_CB_FAST_CHECK)
# capture (each view):
corners = cv2.cornerSubPix(gray, corners, (11, 11), (-1, -1), criteria)
objpoints.append(objp); imgpoints.append(corners)

rms, K, dist, rvecs, tvecs, std_in, std_ex, per_view = \
    cv2.calibrateCameraExtended(objpoints, imgpoints, (w, h), None, None)

newK, roi = cv2.getOptimalNewCameraMatrix(K, dist, (w, h), alpha)
mapx, mapy = cv2.initUndistortRectifyMap(K, dist, None, newK, (w, h), cv2.CV_32FC1)
undistorted = cv2.remap(frame, mapx, mapy, cv2.INTER_LINEAR)

ok, rvec, tvec = cv2.solvePnP(objp, corners, K, dist)   # distance = |tvec|

It is the real OpenCV-Python 4.10 compiled to WebAssembly (Pyodide), running inside a Web Worker. Your video never leaves your computer.