title: matcher GMS opencv
body: <p>I'd like to find the corresponding points on the frames using the gms matcher(<a href="https://docs.opencv.org/3.4.2/db/dd9/group__xfeatures2d__match.html" rel="nofollow noreferrer">https://docs.opencv.org/3.4.2/db/dd9/group__xfeatures2d__match.html</a>). So I write:</p>
  
  <pre><code>import copy
  import cv2
  from cv2.xfeatures2d import matchGMS
  
  def match(img1, img2):
      kp1, des1 = orb.detectAndCompute(img1, None)
      kp2, des2 = orb.detectAndCompute(img2, None)
      matcher = cv2.BFMatcher(cv2.NORM_HAMMING)
      matches_all = matcher.match(des1, des2)
      matches_gms = matchGMS(img1.shape, img2.shape, kp1, kp2, matches_all)
      return matches_gms
  
  cap = cv2.VideoCapture(path_to_video)
  frame1 = None
  frame2 = None
  while(cap.isOpened()):    
      state, frame2 = cap.read()
      frame2 = cv2.cvtColor(frame2, cv2.COLOR_BGR2GRAY)
      matches_gms = []
      if frame1 is not None:   
          matches_gms = match(frame1, frame2)
      frame1 = copy.copy(frame2)
  
  cap.release()
  </code></pre>
  
  <p>But when I call the second time <code>match(frame1, frame2)</code>, I get an error <code>'cv2.DMatch' object is not callable</code>. What should I do?</p>