python opencv SIFT，获取特征点的坐标位置

参考地址：https://docs.opencv.org/3.4/d2/d29/classcv_1_1KeyPoint.html

测试代码：

import cv2  
import numpy as np  
  
img = cv2.imread('4.jpg',cv2.IMREAD_COLOR)  
gray = cv2.cvtColor(img,cv2.COLOR_BGR2GRAY)  
# cv2.imshow('origin',img)
  
#SIFT  
detector = cv2.xfeatures2d.SIFT_create()
keypoints = detector.detect(gray,None)  
cv2.drawKeypoints(gray,keypoints,img)  

points2f = cv2.KeyPoint_convert(keypoints)  #将KeyPoint格式数据中的xy坐标提取出来。
print(keypoints)
print(points2f)

cv2.imshow('test',img)

cv2.waitKey(0)  
cv2.destroyAllWindows() 

测试效果：