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- import cv2
- import numpy as np
- from matplotlib import pyplot as plt
- # K2 = np.float32([[1357.3, 0, 441.413], [0, 1355.9, 259.393], [0, 0, 1]]).reshape(3,3)
- # K1 = np.float32([[1345.8, 0, 394.9141], [0, 1342.9, 291.6181], [0, 0, 1]]).reshape(3,3)
- # K1_inv = np.linalg.inv(K1)
- # K2_inv = np.linalg.inv(K2)
- K = np.float32([3541.5, 0, 2088.8, 0, 3546.9, 1161.4, 0, 0, 1]).reshape(3,3)
- K_inv = np.linalg.inv(K)
- def in_front_of_both_cameras(first_points, second_points, rot, trans):
- # check if the point correspondences are in front of both images
- rot_inv = rot
- for first, second in zip(first_points, second_points):
- first_z = np.dot(rot[0, :] - second[0]*rot[2, :], trans) / np.dot(rot[0, :] - second[0]*rot[2, :], second)
- first_3d_point = np.array([first[0] * first_z, second[0] * first_z, first_z])
- second_3d_point = np.dot(rot.T, first_3d_point) - np.dot(rot.T, trans)
- if first_3d_point[2] < 0 or second_3d_point[2] < 0:
- return False
- return True
- def drawlines(img1,img2,lines,pts1,pts2):
- ''' img1 - image on which we draw the epilines for the points in img1
- lines - corresponding epilines '''
- pts1 = np.int32(pts1)
- pts2 = np.int32(pts2)
- r,c = img1.shape
- img1 = cv2.cvtColor(img1,cv2.COLOR_GRAY2BGR)
- img2 = cv2.cvtColor(img2,cv2.COLOR_GRAY2BGR)
- for r,pt1,pt2 in zip(lines,pts1,pts2):
- color = tuple(np.random.randint(0,255,3).tolist())
- x0,y0 = map(int, [0, -r[2]/r[1] ])
- x1,y1 = map(int, [c, -(r[2]+r[0]*c)/r[1] ])
- cv2.line(img1, (x0,y0), (x1,y1), color,1)
- cv2.circle(img1,tuple(pt1), 10, color, -1)
- cv2.circle(img2,tuple(pt2), 10,color,-1)
- return img1,img2
- img1 = cv2.imread('C:\\Users\\Sai\\Desktop\\room1.jpg', 0)
- img2 = cv2.imread('C:\\Users\\Sai\\Desktop\\room0.jpg', 0)
- img1 = cv2.resize(img1, (0,0), fx=0.5, fy=0.5)
- img2 = cv2.resize(img2, (0,0), fx=0.5, fy=0.5)
- sift = cv2.SIFT()
- # find the keypoints and descriptors with SIFT
- kp1, des1 = sift.detectAndCompute(img1,None)
- kp2, des2 = sift.detectAndCompute(img2,None)
- # FLANN parameters
- FLANN_INDEX_KDTREE = 0
- index_params = dict(algorithm = FLANN_INDEX_KDTREE, trees = 5)
- search_params = dict(checks=50) # or pass empty dictionary
- flann = cv2.FlannBasedMatcher(index_params,search_params)
- matches = flann.knnMatch(des1,des2,k=2)
- good = []
- pts1 = []
- pts2 = []
- # ratio test as per Lowe's paper
- for i,(m,n) in enumerate(matches):
- if m.distance < 0.7*n.distance:
- good.append(m)
- pts2.append(kp2[m.trainIdx].pt)
- pts1.append(kp1[m.queryIdx].pt)
- pts2 = np.float32(pts2)
- pts1 = np.float32(pts1)
- F, mask = cv2.findFundamentalMat(pts1,pts2,cv2.FM_RANSAC)
- # Selecting only the inliers
- pts1 = pts1[mask.ravel()==1]
- pts2 = pts2[mask.ravel()==1]
- F, mask = cv2.findFundamentalMat(pts1,pts2,cv2.FM_8POINT)
- print "Fundamental matrix is"
- print
- print F
- pt1 = np.array([[pts1[0][0]], [pts1[0][1]], [1]])
- pt2 = np.array([[pts2[0][0], pts2[0][1], 1]])
- print "Fundamental matrix error check: %f"%np.dot(np.dot(pt2,F),pt1)
- print " "
- # drawing lines on left image
- lines1 = cv2.computeCorrespondEpilines(pts2.reshape(-1,1,2), 2,F)
- lines1 = lines1.reshape(-1,3)
- img5,img6 = drawlines(img1,img2,lines1,pts1,pts2)
- # drawing lines on right image
- lines2 = cv2.computeCorrespondEpilines(pts1.reshape(-1,1,2), 1,F)
- lines2 = lines2.reshape(-1,3)
- img3,img4 = drawlines(img2,img1,lines2,pts2,pts1)
- E = K.T.dot(F).dot(K)
- print "The essential matrix is"
- print E
- print
- U, S, Vt = np.linalg.svd(E)
- W = np.array([0.0, -1.0, 0.0, 1.0, 0.0, 0.0, 0.0, 0.0, 1.0]).reshape(3, 3)
- first_inliers = []
- second_inliers = []
- for i in range(len(pts1)):
- # normalize and homogenize the image coordinates
- first_inliers.append(K_inv.dot([pts1[i][0], pts1[i][1], 1.0]))
- second_inliers.append(K_inv.dot([pts2[i][0], pts2[i][1], 1.0]))
- # Determine the correct choice of second camera matrix
- # only in one of the four configurations will all the points be in front of both cameras
- # First choice: R = U * Wt * Vt, T = +u_3 (See Hartley Zisserman 9.19)
- R = U.dot(W).dot(Vt)
- T = U[:, 2]
- if not in_front_of_both_cameras(first_inliers, second_inliers, R, T):
- # Second choice: R = U * W * Vt, T = -u_3
- T = - U[:, 2]
- if not in_front_of_both_cameras(first_inliers, second_inliers, R, T):
- # Third choice: R = U * Wt * Vt, T = u_3
- R = U.dot(W.T).dot(Vt)
- T = U[:, 2]
- if not in_front_of_both_cameras(first_inliers, second_inliers, R, T):
- # Fourth choice: R = U * Wt * Vt, T = -u_3
- T = - U[:, 2]
- # Computing Euler angles
- thetaX = np.arctan2(R[1][2], R[2][2])
- c2 = np.sqrt((R[0][0]*R[0][0] + R[0][1]*R[0][1]))
- thetaY = np.arctan2(-R[0][2], c2)
- s1 = np.sin(thetaX)
- c1 = np.cos(thetaX)
- thetaZ = np.arctan2((s1*R[2][0] - c1*R[1][0]), (c1*R[1][1] - s1*R[2][1]))
- print "Pitch: %f, Yaw: %f, Roll: %f"%(thetaX*180/3.1415, thetaY*180/3.1415, thetaZ*180/3.1415)
- print "Rotation matrix:"
- print R
- print
- print "Translation vector:"
- print T
- plt.subplot(121),plt.imshow(img5)
- plt.subplot(122),plt.imshow(img3)
- plt.show()
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