增加特征匹配

data/1.OpenCV初阶/4.几何变换和图像特征/4.特征匹配/match.md

+# 如影随形
+
+通过特征匹配，可以把亭子和水中的倒影做特征匹配
+
+![](./tower_match.jpeg)
+
+框架代码如下：
+
+```python
+import cv2
+import numpy as np
+
+if __name__ == '__main__':
+    img1 = cv2.imread('tower01.jpg', -1)
+    img2 = cv2.imread('tower02.jpg', -1)
+
+    # TODO(You):  请在此实现代码
+    
+    cv2.imwrite('tower_match.jpeg', match_img)
+    cv2.waitKey()
+    cv2.destroyAllWindows()
+```
+
+以下代码实现正确的是？
+
+## 答案
+
+```python
+orb = cv2.ORB_create(nfeatures=500)
+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)
+match_img = cv2.drawMatches(img1, kp1, img2, kp2, matches[:50], None)
+```
+
+## 选项
+
+### 检测错误
+
+```python
+kp1, des1 = cv2.detectAndCompute(img1, None)
+kp2, des2 = cv2.detectAndCompute(img2, None)
+
+bf = cv2.BFMatcher(cv2.NORM_HAMMING, crossCheck=True)
+matches = bf.match(des1, des2)
+
+matches = sorted(matches, key=lambda x: x.distance)
+match_img = cv2.drawMatches(img1, kp1, img2, kp2, matches[:50], None)
+```
+
+### 匹配错误
+
+```python
+orb = cv2.ORB_create(nfeatures=500)
+kp1, des1 = orb.detectAndCompute(img1, None)
+kp2, des2 = orb.detectAndCompute(img2, None)
+
+matches = cv2.match(des1, des2)
+
+matches = sorted(matches, key=lambda x: x.distance)
+match_img = cv2.drawMatches(img1, kp1, img2, kp2, matches[:50], None)
+```
+
+### 排序错误
+
+```python
+orb = cv2.ORB_create(nfeatures=500)
+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)
+match_img = bf.drawMatches(img1, kp1, img2, kp2, matches[:50], None)
+```

data/1.OpenCV初阶/4.几何变换和图像特征/4.特征匹配/match.py

+import cv2
+import numpy as np
+
+
+if __name__ == '__main__':
+    img1 = cv2.imread('tower01.jpg', -1)
+    img2 = cv2.imread('tower02.jpg', -1)
+
+    orb = cv2.ORB_create(nfeatures=500)
+    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)
+    match_img = cv2.drawMatches(img1, kp1, img2, kp2, matches[:50], None)
+    # cv2.imwrite('tower_match.jpeg', match_img)
+    cv2.imshow('Matches', match_img)
+    cv2.waitKey()