pythonopencvcorner-detection

Where is the FAST algorithm in OpenCV?


I'm not able to find the FAST corner detector in the Python OpenCV module, I tried this this like described in that link. My OpenCV version is 3.1.0.

I know that feature-description algorithms like SIFT and SURF were shifted to cv2.xfeatures2d, but the FAST algorithm is not located there.


Solution

  • According to opencv-3.1.0 documentation You can run FAST in python this way:

    import numpy as np
    import cv2
    from matplotlib import pyplot as plt
    
    img = cv2.imread('simple.jpg',0)
    
    # Initiate FAST object with default values
    fast = cv2.FastFeatureDetector_create()
    
    # find and draw the keypoints
    kp = fast.detect(img,None)
    img2 = cv2.drawKeypoints(img, kp, color=(255,0,0))
    
    # Print all default params
    print "Threshold: ", fast.getInt('threshold')
    print "nonmaxSuppression: ", fast.getBool('nonmaxSuppression')
    print "neighborhood: ", fast.getInt('type')
    print "Total Keypoints with nonmaxSuppression: ", len(kp)
    
    cv2.imwrite('fast_true.png',img2)
    
    # Disable nonmaxSuppression
    fast.setBool('nonmaxSuppression',0)
    kp = fast.detect(img,None)
    
    print "Total Keypoints without nonmaxSuppression: ", len(kp)
    
    img3 = cv2.drawKeypoints(img, kp, color=(255,0,0))
    
    cv2.imwrite('fast_false.png',img3)