Hi,
I am trying to use python functions from [omnidir namespace](http://docs.opencv.org/trunk/db/dd2/namespacecv_1_1omnidir.html) in **opencv 3.1.0** for calibrating a Fisheye camera and undistorting the images in `RECTIFY_CYLINDRICAL` mode. I am unable to figure out what should be the shape of `objectPoints` and `imagePoints` argurments passed to `cv2.omnidir.calibrate()`. Here is my code:
import numpy as np
import cv2
import glob
nx = 9
ny = 6
# termination criteria
criteria = (cv2.TERM_CRITERIA_EPS + cv2.TERM_CRITERIA_MAX_ITER, 30, 0.001)
chessboard_model = np.zeros((1, nx*ny, 3), np.float32)
chessboard_model[0, :, :2] = np.mgrid[0:nx, 0:ny].T.reshape(-1, 2)
# prepare object points, like (0,0,0), (1,0,0), (2,0,0) ....,(6,5,0)
objp = np.zeros((nx*ny, 3), np.float32)
objp[:,:2] = np.mgrid[0:nx, 0:ny].T.reshape(-1,2)
# Arrays to store object points and image points from all the images.
objpoints = [] # 3d point in real world space
imgpoints = [] # 2d points in image plane.
filenames = glob.glob('/home/work/Downloads/fisheye_calibration/*.jpg')
images = []
for fname in filenames:
img = cv2.imread(fname)
gray = cv2.cvtColor(img,cv2.COLOR_BGR2GRAY)
images.append(img)
# Find the chess board corners
ret, corners = cv2.findChessboardCorners(gray, (nx,ny),None)
# If found, add object points, image points (after refining them)
if ret == True:
objpoints.append(objp)
corners2 = cv2.cornerSubPix(gray,corners,(11,11),(-1,-1),criteria)
imgpoints.append(corners2.reshape(1, -1, 2))
# Draw and display the corners
img = cv2.drawChessboardCorners(img, (nx,ny), corners2,ret)
cv2.imshow('img',img)
cv2.waitKey(500)
num_points = len(imgpoints)
K = np.zeros((3, 3))
xi = np.array([])
D = np.zeros((4, 1))
h, w = images[-1].shape[:2]
calibration_flags = cv2.omnidir.CALIB_USE_GUESS | cv2.omnidir.CALIB_FIX_SKEW
obj_points_arr = np.array([chessboard_model]*num_points)
img_points_arr = np.array(imgpoints).squeeze(axis=1)
rms = cv2.omnidir.calibrate(obj_points_arr, img_points_arr, (w,h), K, xi, D, calibration_flags, criteria)
I got the following error with above code:
cv2.error: /home/work/modules/ccalib/src/omnidir.cpp:1065: error: (-215) !patternPoints.empty() && !imagePoints.empty() && patternPoints.total() == imagePoints.total() in function calibrate
In above code, object_points_arr and image_points_arr are of shapes `num_points X 1 X (nx * ny) X 3` and `num_points X 1 X (nx * ny) X 2` respectively. If object_points_arr and image_points_arr are reshaped to `num_points X (nx * ny) X 3` and `num_points X (nx * ny) X 2` respectively then I get the following error
cv2.error: /home/work/opencv/modules/core/src/matrix.cpp:469: error: (-215) 0 <= _rowRange.start && _rowRange.start <= _rowRange.end && _rowRange.end <= m.rows in function Mat
What are the expected the shapes ? Can someone please share working Python code for omnidir camera calibration and image rectification using opencv.
Thanks !
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