计算关键点
keypoints = cv.Feature2D.detect( image[, mask] )
keypoints = cv.Feature2D.detect( images[, masks] )
计算描述
keypoints, descriptors = cv.Feature2D.compute( image, keypoints[, descriptors] )
keypoints, descriptors = cv.Feature2D.compute( images, keypoints[, descriptors] )
计算关键点和描述
keypoints, descriptors = cv.Feature2D.detectAndCompute( image, mask[, descriptors[, useProvidedKeypoints]] )
检测关键点并计算关键点的特征信息
参数描述
image图片指针keypoints检测点masksMasks for each input image specifying where to look for keypoints (optional)descriptors
参考文献： https://docs.opencv.org/3.4.3/d0/d13/classcv_1_1Feature2D.html#a8be0d1c20b08eb867184b8d74c15a677
