OpenCV Python:没有drawMatchesknn函数 [英] OpenCV Python : No drawMatchesknn function

问题描述

当我尝试使用

When I tried to use drawMatchesKnn function as mentioned in this tutorial for FLANN feature matching, I get the following error

AttributeError:模块"对象没有属性"drawMatchesKnn"

AttributeError: 'module' object has no attribute 'drawMatchesKnn'

我与其他资源一起检查了opencv中是否存在drawMatchesKnn方法.

I checked with other resources that drawMatchesKnn method is present in opencv.

为什么会出现此错误?

预先感谢

推荐答案

功能cv2.drawMatches和cv2.drawMatchesKnn在较新版本的OpenCV 2.4中不可用. @rayryeng提供了一个轻量级替代，它可以与DescriptorMatcher.match的输出一样使用.与DescriptorMatcher.knnMatch的区别在于，匹配项以列表列表的形式返回.要使用@rayryeng替代项，必须将匹配项提取到一维列表中.

The functions cv2.drawMatches and cv2.drawMatchesKnn are not available in newer versions of OpenCV 2.4. @rayryeng provided a lightweight alternative which works as is for the output of DescriptorMatcher.match. The difference with DescriptorMatcher.knnMatch is that the matches are returned as a list of lists. To use the @rayryeng alternative, the matches must be extracted into a 1-D list.

例如，与SIFT描述符和比率测试的蛮力匹配教程可以作如下修改:

For example, the Brute-Force Matching with SIFT Descriptors and Ratio Test tutorial could be amended as such:

# BFMatcher with default params
bf = cv2.BFMatcher()
matches = bf.knnMatch(des1,des2, k=2)

# Apply ratio test
good = []
for m,n in matches:
    if m.distance < 0.75*n.distance:
       # Removed the brackets around m 
       good.append(m)

# Invoke @rayryeng's drawMatches alternative, note it requires grayscale images
gray1 = cv2.cvtColor(img1,cv2.COLOR_BGR2GRAY)
gray2 = cv2.cvtColor(img2,cv2.COLOR_BGR2GRAY)
drawMatches(gray1,kp1,gray2,kp2,good)

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