如何检测对象球（使用opencv进行跟踪）是否通过给定区域

Question

I am trying to develop a foosball game analysis app. I am able to track the ball using opencv color based tracking. the real problem is goal detection. possible solution is- if a ball passed through a marked area on the goal, and the ball vanishes from the table for a significant time, it can be considered as a goal and the goal counter should be incremented.

I went through a lot of code on github and stackoverflow, but can't correctly implement the needs.

from collections import deque
from imutils.video import VideoStream
import numpy as np
import argparse
import cv2
import imutils
import time

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())
match_score = (0, 0)

greenLower = (29, 86, 6)
greenUpper = (64, 255, 255)

pts = deque(maxlen=args["buffer"])
counter = 0
(dX, dY) = (0, 0)
direction = ""

if not args.get("video", False):
    vs = VideoStream(src=1).start()
else:
    vs = cv2.VideoCapture(args["video"])

time.sleep(2.0)

while True:

frame = vs.read()


frame = frame[1] if args.get("video", False) else frame
if frame is None:
    break

frame = imutils.resize(frame, width=640, height=480)
blurred = cv2.GaussianBlur(frame, (11, 11), 0)
hsv = cv2.cvtColor(blurred, cv2.COLOR_BGR2HSV)

mask = cv2.inRange(hsv, greenLower, greenUpper)
mask = cv2.erode(mask, None, iterations=2)
mask = cv2.dilate(mask, None, iterations=2)
cnts = cv2.findContours(mask.copy(), cv2.RETR_EXTERNAL,
    cv2.CHAIN_APPROX_SIMPLE)
cnts = imutils.grab_contours(cnts)
center = None
cv2.rectangle(frame,(0,0),(640,360),(0,255,255),7)
cv2.line(frame,(10,135),(10,225),(255,0,0),7)
cv2.line(frame,(625,140),(625,230),(255,0,0),7)
cv2.putText(frame, str(match_score[0]) + " - " + str(match_score[1]), (260, 60), cv2.FONT_HERSHEY_SIMPLEX, 1, (120, 255, 50), 2)

if len(cnts) > 0:
    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"]))

    if radius > 5:
        # 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)


pts.appendleft(center)
for i in range(1, len(pts)):
    if pts[i - 1] is None or pts[i] is None:
        continue
    if counter >= 10 and i == 1 and pts[-10] is not None:
        dX = pts[-10][0] - pts[i][0]
        dY = pts[-10][1] - pts[i][1]
        (dirX, dirY) = ("", "")

    thickness = int(np.sqrt(args["buffer"] / float(i + 1)) * 2.5)
    cv2.line(frame, pts[i - 1], pts[i], (0, 0, 255), thickness)
cv2.putText(frame, direction, (10, 30), cv2.FONT_HERSHEY_SIMPLEX,
    0.65, (0, 0, 255), 3)
cv2.putText(frame, "dx: {}, dy: {}".format(dX, dY),
    (10, frame.shape[0] - 10), cv2.FONT_HERSHEY_SIMPLEX,
    0.5, (0, 0, 255), 1)

cv2.imshow("Frame", frame)
key = cv2.waitKey(1) & 0xFF
counter += 1
if key == ord("q"):
    break

if not args.get("video", False):
    vs.stop()
else:
    vs.release()

cv2.destroyAllWindows()

these are the clips I am currently using. https://drive.google.com/file/d/1Y7Dzzfx_V0fsDZRZAC4d0MuEpSnKnodI/view?usp=sharing https://drive.google.com/file/d/1jazU_-tdp9e-nALTqT04_U_8gj8rovSL/view?usp=sharing

python trackball.py --video test3.mp4

I am completely open to new suggestions!

Answer 1

Use a voting algorithm to determine if a goal has been scored. Find the location of the goal in the image. If the tracked position of the ball is inside the goal, increment votes. If there are several votes for a goal, count the goal.

This voting method will help eliminate erroneous tracking values.

# Find the ball position (an x,y coordinate)
x, y = ball_position
# Find the goal position (a rectangle)
goal_x, goal_y, width, height = 0, 400, 50, 170
# Is the ball inside the goal?
if x>goal_x and p<goal_x+width and y>goal_y and y<goal_y+height: votes += 1
else: votes -= .1
if votes < 0: votes = 0
if votes > 7: print('goal!')