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我是 OpenCV 的新手，决定学习它，但编写了一个小程序来检测运动并在对象上绘制一个边界框。

我从一个相当简单的方法开始，它简单地计算两帧之间的差异，找到轮廓并在对象周围绘制一个简单的矩形。这在一段时间内达到了目的，但它无法在多个对象弹出时自主跟踪它们。我必须手动更改我的参数才能跟踪n个对象。

所以我决定改变我的方法，改用BackgroundSubtractorMOG. 这种方法更适合我想要完成的工作，但我目前唯一遇到的问题是如何在应用后绘制检测到的对象的轮廓BackgroundSubtractorMOG。我不再想要矩形，而是希望它围绕对象的边框绘制。

import sys
import cv2

def getImageDifference(first, second):
    return cv2.absdiff(first, second)

def drawRectangle(contour, frame):
        (x, y, w, h) = cv2.boundingRect(contour)
        cv2.rectangle(frame, (x, y), (x + w, y + h), (0, 255, 0), 2)

previousFrame = None
backgroundSubtractor = None
camera = cv2.VideoCapture(0)
backgroundSubtractor = cv2.BackgroundSubtractorMOG()

while True:
    grabbed, frame = camera.read()

    if not grabbed:
        break

    fgMask = backgroundSubtractor.apply(frame, learningRate = 1.0/10)
    output = cv2.GaussianBlur(fgMask, (21, 21), 0)

    if previousFrame is None:
        previousFrame = fgMask
        continue

    frameDelta = getImageDifference(previousFrame, output)
    maskRGB = cv2.cvtColor(fgMask,cv2.COLOR_GRAY2BGR)
    frameDela = maskRGB
#    frameDelta = cv2.cvtColor(fgMask, cv2.COLOR_BGR2GRAY)
    threshold = cv2.threshold(fgMask, 21, 255, cv2.THRESH_BINARY)[1]

    threshold = cv2.dilate(threshold, None, iterations = 2)

    contours, hierarchy = cv2.findContours(threshold.copy(), cv2.RETR_EXTERNAL, cv2.CHAIN_APPROX_SIMPLE)

    sortedContours = sorted(contours, key = cv2.contourArea, reverse = True)[:2] #this will track two objects simultaneously. If I want more, I'd have to come and change this value to whatever I want

    for contour in sortedContours:

        drawRectangle(contour, frame)
        previousFrame = output

    draw = frame & maskRGB

    cv2.imshow('Main',frame)
    cv2.imshow('Background Subtraction', fgMask)
    cv2.imshow('Background Subtraction with color', draw)
    if cv2.waitKey(1) & 0xFF == ord('q'):
        break

camera.release()
cv2.destroyAllWindows()
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