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import cv2
import numpy as np
from matplotlib import pyplot as plt
def drawlines(img1,img2,lines,pts1,pts2):
''' img1 - image on which we draw the epilines for the points in img1
lines - corresponding epilines '''
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] ])
img1 = cv2.line(img1, (x0,y0), (x1,y1), color,1)
img1 = cv2.circle(img1,tuple(pt1),5,color,-1)
img2 = cv2.circle(img2,tuple(pt2),5,color,-1)
return img1,img2
img1 = cv2.imread('1.jpg',0) # queryimage
img2 = cv2.imread('2.jpg',0) #trainimage
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.int32(pts2)
pts1 = np.int32(pts1)
F, mask = cv2.findFundamentalMat(pts1,pts2,cv2.FM_RANSAC)
# We select only first 15 points
pts1 = pts1[mask.ravel()==1][:15]
pts2 = pts2[mask.ravel()==1][:15]
lines = cv2.computeCorrespondEpilines(pts2.reshape(-1,1,2), 2,F)
lines = lines.reshape(-1,3)
img3,img4 = drawlines(img1,img2,lines,pts1,pts2)
plt.subplot(121),plt.imshow(img3)
plt.subplot(122),plt.imshow(img4)
plt.show()
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