求助 怎么判断ORB特征的连线是否平行

网上搜了一个ORB特征匹配的程序 想应用于指纹识别 想判断之间的连线是否平行 以判断是否是同一个指纹 源程序如下 求判断程序
import numpy as np
import cv2
from matplotlib import pyplot as plt
img1 = cv2.imread('D:/1.bmp',0)
img2 = cv2.imread('D:/2.bmp',0)
orb = cv2.ORB_create()
kp1, des1 = orb.detectAndCompute(img1,None)
kp2, des2 = orb.detectAndCompute(img2,None)
bf = cv2.BFMatcher(cv2.NORM_HAMMING, crossCheck=True)
matches = bf.match(des1,des2)
matches = sorted(matches, key = lambda x:x.distance)
img3=np.empty((300,300))
img3 = cv2.drawMatches(img1,kp1,img2,kp2,matches[:10], img3,flags=2)
plt.imshow(img3),plt.show()