问题
I followed a blob detection example (using cv2.SimpleBlobDetector
) and successfully detected the blobs in my binary image. But then I don't know how to extract the coordinates and area of the keypoints. Here are the code for the blob detections:
# I skipped the parameter setting part.
blobParams = cv2.SimpleBlobDetector_Params()
blobVer = (cv2.__version__).split('.')
if int(blobVer[0]) < 3:
detector = cv2.SimpleBlobDetector(blobParams)
else:
detector = cv2.SimpleBlobDetector_create(blobParams)
# Detect Blobs
keypoints_black = detector.detect(255-black_blob)
trans_blobs = cv2.drawKeypoints(gray_video_crop, \
keypoints_white, np.array([]), (0,0,255), cv2.DRAW_MATCHES_FLAGS_DRAW_RICH_KEYPOINTS)
So the variable keypoints_black
contains the information of the blob(s). When I printed the variable it looked something like this (2 blobs were found):
KeyPoint 0x10b10b870, KeyPoint 0x10b1301b0
So how to I get the coordinates of the centre of mass of the keypoints and their area so that I can send them as osc messages for interaction.
回答1:
The pt
property:
keypoints = detector.detect(frame) #list of blobs keypoints
x = keypoints[i].pt[0] #i is the index of the blob you want to get the position
y = keypoints[i].pt[1]
Some documentation
回答2:
If you have a list of keypoints. Then you can print as shown below
for keyPoint in keyPoints:
x = keyPoint.pt[0]
y = keyPoint.pt[1]
s = keyPoint.size
Edit: Size determines the diameter of the meaningful keypoint neighborhood. You can use that size and roughly calculate the area of the blob.
来源:https://stackoverflow.com/questions/30807214/opencv-return-keypoints-coordinates-and-area-from-blob-detection-python