I am trying to calibrate camera using OpenCV tools according to the following. The problem is that function findChessboardCorners cannot find any chessboard on images I tried. I used a lot of them - even just plain chessboard pattern. In any case, nothing was detected. Here is the code (almost the same as from link above): import numpy as np import cv2 import glob # termination criteria criteria = (cv2.TERMCRITERIAEPS + cv2.TERMCRITERIAMAXITER, 30, 0.001) # prepare object points, like (0,0,0), (1,0,0), (2,0,0).,(6,5,0) objp = np.zeros((6.7,3), np.float32) objp:,:2 = np.mgrid0:7,0:6.T.reshape(-1,2) # Arrays to store object points and image points from all the images.

• Opencv Android Tutorials
• Opencv Chessboard Pattern

The placement of the camera and the objects should not be disturbed during calibration and later during capture. Print out a chessboard image to A4 paper. For example, I use this chessboard image that is available with OpenCV documentation files. Paste or fix the printed chessboard to a board or pad.

Opencv Android Tutorials

Objpoints = # 3d point in real world space imgpoints = # 2d points in image plane. Just for other Python newbies that may go down this road. Working code: import numpy as np import cv2 import glob # termination criteria criteria = (cv2.TERMCRITERIAEPS + cv2.TERMCRITERIAMAXITER, 30, 0.001) # Arrays to store object points and image points from all the images. Imgpoints = # 2d points in image plane. Images = glob.glob('.png') for fname in images: img = cv2.imread(fname) gray = cv2.cvtColor(img,cv2.COLORBGR2GRAY) ret = False # Find the chess board corners ret, corners = cv2.findChessboardCorners(gray, (7,7)) # If found, add object points, image points (after refining them) if ret True: cv2.cornerSubPix(gray, corners, (11,11), (-1,-1), criteria) imgpoints.append(corners) # Draw and display the corners cv2.drawChessboardCorners(img, (7,7), corners, ret) cv2.imshow('img',img) cv2.waitKey(0) cv2.destroyAllWindows Two main points:.

You have to carefully count dimension of you pattern. (7,7) is for usual chessboard. Line img = cv2.drawChessboardCorners(img, (7,6), corners2,ret) doesn't work, you have to change it to cv2.drawChessboardCorners(img, (7,6), corners2,ret) (function doesn't return image). Thanks to AldurDisciple!

I know there is some post talking about this topic but I could not find my answer. I want to calibrate my android camera without chessboard for 3d reconstruction, so I need my intrinsic and extrinsic parameters. My first goal is to extract the 3D real system to be able to put some 3d Model on screen. My step:. From a picture of a building I extract 4 points that represent the real 3D system. /!

Opencv Chessboard Pattern

This step require camera calibration /! Convert them to 3d Point (solvePnP for exemple). Then from my 3D Axis I create a OpenGL projection and modelview matrix My main problem is that I want to avoid a calibration step, so how can calibrate without chessboard? I have some data from android such as focal length. I can guess that the projection center is the center of my camera picture. Any idea or advice?

Or other way to do it?