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How do you create a bounding box on retroreflective tape?

asked 2017-01-14 17:22:37 -0500

Smosher104 gravatar image

updated 2017-01-15 02:19:50 -0500

berak gravatar image

Hello everyone. I am an FRC programmer and I have been trying to track a piece of retro reflective tape with a green led ring shining on it in opencv python. I have gotten to the point where I can create a calibrated hsv lower_green and upper_green numpy array, and black out everything, but the tape. However, I have no idea how to detect the rectangular piece of retroreflective tape and draw a bounding box around. Any help would be deeply appreciated.

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answered 2017-01-15 02:19:06 -0500

berak gravatar image

actually, getting the lower/upper bounds right is the hardest thing here, then it needs a few more steps:

# binarized image:
bin = cv2.inRange(hsv, lower,upper)

# contours:
im2, contours,hierarchy = cv2.findContours(bin,2,1)  # without 'im2' for opencv2.4 !!
if len(contours)>0:
    cnt = contours[0]
    (x,y,w,h) = cv2.boundingRect(cnt)
    cv2.rectangle(img, (x,y), (x+w,y+h), (255,0,0), 1)
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Oh my god! Thank you so much! Notonly does this work perfectly, but it really helped me understand how contours work!

Smosher104 gravatar imageSmosher104 ( 2017-01-15 18:08:00 -0500 )edit
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Asked: 2017-01-14 17:22:37 -0500

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Last updated: Jan 15 '17