Matching Features with ORB python opencv

问题:

hi im working in Matching Features with ORB python opencv but when i run this code i get this error Traceback (most recent call last): File "ffl.py", line 27, in for m,n in matches: TypeError: 'cv2.DMatch' object is not iterable

i don't know how to fix it

import numpy as np import cv2 import time  ESC=27    camera = cv2.VideoCapture(0) orb = cv2.ORB_create() bf = cv2.BFMatcher(cv2.NORM_HAMMING, crossCheck=True)  imgTrainColor = cv2.imread('/home/shar/home.jpg') imgTrainGray = cv2.cvtColor(imgTrainColor, cv2.COLOR_BGR2GRAY)  kpTrain = orb.detect(imgTrainGray,None) kpTrain, desTrain = orb.compute(imgTrainGray, kpTrain)  firsttime = True  while True:      ret, imgCamColor = camera.read()     imgCamGray = cv2.cvtColor(imgCamColor, cv2.COLOR_BGR2GRAY)     kpCam = orb.detect(imgCamGray,None)     kpCam, desCam = orb.compute(imgCamGray, kpCam)     bf = cv2.BFMatcher(cv2.NORM_HAMMING, crossCheck=True)     matches = bf.match(desCam,desTrain)     good = []     for m,n in matches:         if m.distance < 0.7*n.distance:             good.append(m)      if firsttime==True:         h1, w1 = imgCamColor.shape[:2]         h2, w2 = imgTrainColor.shape[:2]         nWidth = w1+w2         nHeight = max(h1, h2)         hdif = (h1-h2)/2         firsttime=False      result = np.zeros((nHeight, nWidth, 3), np.uint8)     result[hdif:hdif+h2, :w2] = imgTrainColor     result[:h1, w2:w1+w2] = imgCamColor      for i in range(len(matches)):         pt_a=(int(kpTrain[matches[i].trainIdx].pt[0]), int(kpTrain[matches[i].trainIdx].pt[1]+hdif))         pt_b=(int(kpCam[matches[i].queryIdx].pt[0]+w2), int(kpCam[matches[i].queryIdx].pt[1]))         cv2.line(result, pt_a, pt_b, (255, 0, 0))      cv2.imshow('Camara', result)      key = cv2.waitKey(20)                                      if key == ESC:         break  cv2.destroyAllWindows() camera.release() 

回答1:

bf.match return only a list of single objects, you cannot iterate over it with m,n. Maybe you are confused with bf.knnMatch?

You can just change your code to:

for m in matches:     if m.distance < 0.7:         good.append(m) 

From the Python tutorials of OpenCV (link):

The result of matches = bf.match(des1,des2) line is a list of DMatch objects. This DMatch object has following attributes:

• DMatch.distance - Distance between descriptors. The lower, the better it is.
• DMatch.trainIdx - Index of the descriptor in train descriptors
• DMatch.queryIdx - Index of the descriptor in query descriptors
• DMatch.imgIdx - Index of the train image.

文章来源: Matching Features with ORB python opencv