Learning OpenCV 4 Computer Vision with Python 3 - Third Edition

Anatomy of a keypoint

Each keypoint is an instance of the cv2.KeyPoint class, which has the following properties:

• The pt (point) property contains the x and y coordinates of the keypoint in the image.
• The size property indicates the diameter of the feature.
• The angle property indicates the orientation of the feature, as shown by the radial lines in the preceding processed image.
• The response property indicates the strength of the keypoint. Some features are classified by SIFT as stronger than others, and response is the property you would check to evaluate the strength of a feature.
• The octave property indicates the layer in the image pyramid where the feature was found. Let's briefly review the concept of an image pyramid, which we discussed ...