我想按照http://opencv-python-
tutroals.readthedocs.org/en/latest/py_tutorials/py_feature2d/py_matcher/py_matcher.html中的说明在Python中使用基于flann的匹配器

由于我使用的是OpenCV 3.0.0，因此必须调整有关SIFT检测器初始化的代码。其余部分不变

def calculateMatch(self):
    # Initiate SIFT detector
    sift = cv2.xfeatures2d.SIFT_create()

    # find the keypoints and descriptors with SIFT
    (kp1, desc1) = sift.detectAndCompute(self.image1,None)
    (kp2, desc2) = sift.detectAndCompute(self.image2,None)

    # FLANN parameters
    FLANN_INDEX_KDTREE = 0

    index_params = dict(algorithm = FLANN_INDEX_KDTREE, trees = 5)
    search_params = dict(checks=50)   # or pass empty dictionary

    flann = cv2.FlannBasedMatcher(index_params,search_params)
    matches = flann.knnMatch(desc1,desc2,k=2)

运行代码时，我收到以下消息：

cv2.error: cv2.cpp:161: error: (-215) The data should normally be NULL! in function allocate

在行中：

matches = flann.knnMatch(desc1,desc2,k=2)

另一则评论：如果使用蛮力匹配器，一切正常：

bf = cv2.BFMatcher()
matches = bf.knnMatch(desc1, desc2, k=2)