Imran Ibrahimi Imran Ibrahimi - 1 month ago 18
Python Question

Ball tracker using OpenCV, Python and Raspberry Pi 3 w/ camera module

I can't run this script successfully.
I have tried running it via command line whilst passing arguments and without. I have also tried to run in a virtualenv to no avail. I suspect I am missing a driver for PiCamera to work

# import the necessary packages
from collections import deque
import numpy as np
import argparse
import imutils
import cv2

# construct the argument parse and parse the arguments
ap = argparse.ArgumentParser()
ap.add_argument("-v", "--video",
help="path to the (optional) video file")
ap.add_argument("-b", "--buffer", type=int, default=64,
help="max buffer size")
args = vars(ap.parse_args())

# define the lower and upper boundaries of the "green"
# ball in the HSV color space, then initialize the
# list of tracked points
greenLower = (29, 86, 6)
greenUpper = (64, 255, 255)
pts = deque(maxlen=args["buffer"])

# if a video path was not supplied, grab the reference
# to the webcam
if not args.get("video", False):
camera = cv2.VideoCapture(0)

# otherwise, grab a reference to the video file
else:
camera = cv2.VideoCapture(args["video"])

# keep looping
while True:
# grab the current frame
(grabbed, frame) = camera.read()

# if we are viewing a video and we did not grab a frame,
# then we have reached the end of the video
if args.get("video") and not grabbed:
break

# resize the frame, blur it, and convert it to the HSV
# color space
frame = imutils.resize(frame, width=600)
# blurred = cv2.GaussianBlur(frame, (11, 11), 0)
hsv = cv2.cvtColor(frame, cv2.COLOR_BGR2HSV)

# construct a mask for the color "green", then perform
# a series of dilations and erosions to remove any small
# blobs left in the mask
mask = cv2.inRange(hsv, greenLower, greenUpper)
mask = cv2.erode(mask, None, iterations=2)
mask = cv2.dilate(mask, None, iterations=2)

# find contours in the mask and initialize the current
# (x, y) center of the ball
cnts = cv2.findContours(mask.copy(), cv2.RETR_EXTERNAL,
cv2.CHAIN_APPROX_SIMPLE)[-2]
center = None

# only proceed if at least one contour was found
if len(cnts) > 0:
# find the largest contour in the mask, then use
# it to compute the minimum enclosing circle and
# centroid
c = max(cnts, key=cv2.contourArea)
((x, y), radius) = cv2.minEnclosingCircle(c)
M = cv2.moments(c)
center = (int(M["m10"] / M["m00"]), int(M["m01"] / M["m00"]))

# only proceed if the radius meets a minimum size
if radius > 10:
# draw the circle and centroid on the frame,
# then update the list of tracked points
cv2.circle(frame, (int(x), int(y)), int(radius),
(0, 255, 255), 2)
cv2.circle(frame, center, 5, (0, 0, 255), -1)

# update the points queue
pts.appendleft(center)

# loop over the set of tracked points
for i in xrange(1, len(pts)):
# if either of the tracked points are None, ignore
# them
if pts[i - 1] is None or pts[i] is None:
continue

# otherwise, compute the thickness of the line and
# draw the connecting lines
thickness = int(np.sqrt(args["buffer"] / float(i + 1)) * 2.5)
cv2.line(frame, pts[i - 1], pts[i], (0, 0, 255), thickness)

# show the frame to our screen
cv2.imshow("Frame", frame)
key = cv2.waitKey(1) & 0xFF

# if the 'q' key is pressed, stop the loop
if key == ord("q"):
break`enter code here`

# cleanup the camera and close any open windows
camera.release()
cv2.destroyAllWindows()


Here is my error:

Traceback (most recent call last):
File "/home/pi/ball-tracking/ball_tracking.py", line 48, in <module>
frame = imutils.resize(frame, width=600)
File "/usr/local/lib/python2.7/dist-packages/imutils/convenience.py"`enter code here`, line 45, in resize
(h, w) = image.shape[:2]
AttributeError: 'NoneType' object has no attribute 'shape'

Answer

The 'nonetype' object referred to the frame that was not passed to the resize method.

This is solved by loading the pre-installed v4l2 drivers before running the code as such:

sudo modprobe bcm2835-v4l2