我正在使用OpenCV / Python示例(来自:OpenCV Tutorials)作为指南进行相机校准程序。
问题:如何定制此示例代码以考虑特定棋盘图案上正方形的大小?我对相机校准过程的理解是,必须以某种方式使用此信息,否则由下式给出的值:
cv2.calibrateCamera()
会不正确的。
以下是我的代码中读取图像文件并在校准过程中运行以生成相机矩阵和其他值的部分。
#import cv2
#import numpy as np
#import glob
"""
Corner Finding
"""
# termination criteria
criteria = (cv2.TERM_CRITERIA_EPS + cv2.TERM_CRITERIA_MAX_ITER, 30, 0.001)
# Prepare object points, like (0,0,0), (1,0,0), ....,(6,5,0)
objp = np.zeros((5*5,3), np.float32)
objp[:,:2] = np.mgrid[0:5,0:5].T.reshape(-1,2)
# Arrays to store object points and image points from all images
objpoints = []
imgpoints = []
counting = 0
# Import Images
images = glob.glob('dir/sub dir/Images/*')
for fname in images:
img = cv2.imread(fname) # Read images
gray = cv2.cvtColor(img, cv2.COLOR_BGR2GRAY) # Convert to grayscale
# Find the chess board corners
ret, corners = cv2.findChessboardCorners(gray, (5,5), None)
# if found, add object points, image points (after refining them)
if ret == True:
objpoints.append(objp)
cv2.cornerSubPix(gray, corners, (11,11), (-1,-1), criteria)
imgpoints.append(corners)
#Draw and display corners
cv2.drawChessboardCorners(img, (5,5), corners, ret)
counting += 1
print str(counting) + ' Viable Image(s)'
cv2.imshow('img', img)
cv2.waitKey(500)
cv2.destroyAllWindows()
# Calibrate Camera
ret, mtx, dist, rvecs, tvecs = cv2.calibrateCamera(objpoints, imgpoints, gray.shape[::-1],None,None)
在这里,如果您的方形尺寸假定为30 mm,则将此值乘以objp[:,:2]
。像这样
objp[:,:2] = np.mgrid[0:9,0:6].T.reshape(-1,2)*30 # 30 mm size of square
由于objp[:,:2]
是一组棋盘角点,给定为(0,0),(0,1),(0,2)......(8,5)。 (0,0)点是左上角的方角,(8,5)是右下角的方角。在这种情况下,这些点没有单位,但如果我们将这些值乘以方形大小(例如30毫米),那么这些将变为(0,0),(0,30),......(240,150)是现实世界的单位。在这种情况下,您的翻译向量将在mm units
中。