Question

我正在树莓派4中使用此python程序进行乘客计数。当相机打开并且人员计数完成时，该程序在我的笔记本电脑中运行得很好，但在树莓派4中不起作用。我正在为此项目使用Raspberry pi 4和7“显示器。我认为在尝试打印框架时它没有接受任何框架输入，但没有打印。相机甚至无法启动。谢谢您的帮助。

它显示以下错误：

Unable to stop the stream: Invalid argument
False
None
OpenCV Error: Assertion failed (dims <= 2 && step[0] > 0) in locateROI, file /build/opencv-L65chJ/opencv-3.2.0+dfsg/modules/core/src/matrix.cpp, line 949
Traceback (most recent call last):
  File "/home/pi/Desktop/tracking.py", line 31, in <module>
    fgmask = cv2.blur(frame, (10,10))
cv2.error: /build/opencv-L65chJ/opencv-3.2.0+dfsg/modules/core/src/matrix.cpp:949: error: (-215) dims <= 2 && step[0] > 0 in function locateROI

这是我的代码：

import numpy as np
import math
import cv2
cap = cv2.VideoCapture(1)
fgbg = cv2.bgsegm.createBackgroundSubtractorMOG(history=150, backgroundRatio=0.3)

def line1(x,y):
    return y - (29*x)/96.0 - 300

def line2(x,y):
    return y - (29*x)/96.0 - 500


crossedAbove = 0
crossedBelow = 0
points = set()
pointFromAbove = set()
pointFromBelow = set()

fourcc = cv2.VideoWriter_fourcc(*'XVID')
out = cv2.VideoWriter('pedestrianOutput.avi',fourcc, 25.0, (1920,1080))
font = cv2.FONT_HERSHEY_SIMPLEX
while(1):
    pointInMiddle = set()
    prev = points
    points = set()
    ret, frame = cap.read()
    print(ret)
    print(frame)
    fgmask = frame
    fgmask = cv2.blur(frame, (10,10))
    fgmask = fgbg.apply(fgmask)
    fgmask = cv2.medianBlur(fgmask, 7)
    oldFgmask = fgmask.copy()
    contours, hierarchy = cv2.findContours(fgmask, cv2.RETR_EXTERNAL,1)
    for contour in contours:
        x,y,w,h = cv2.boundingRect(contour)
        if w>40 and h>90:
            cv2.rectangle(frame,(x,y),(x+w,y+h),(0,255,0),2, lineType=cv2.LINE_AA)
            point = (int(x+w/2.0), int(y+h/2.0))
            points.add(point)
    for point in points:
        (xnew, ynew) = point
        if line1(xnew, ynew) > 0 and line2(xnew, ynew) < 0:
            pointInMiddle.add(point)
        for prevPoint in prev:
            (xold, yold) = prevPoint
            dist = cv2.sqrt((xnew-xold)*(xnew-xold)+(ynew-yold)*(ynew-yold))
            if dist[0] <= 120:
                if line1(xnew, ynew) >= 0 and line2(xnew, ynew) <= 0:
                    if line1(xold, yold) < 0: # Point entered from line above
                        pointFromAbove.add(point)
                    elif line2(xold, yold) > 0: # Point entered from line below
                        pointFromBelow.add(point)
                    else:   # Point was inside the block
                        if prevPoint in pointFromBelow:
                            pointFromBelow.remove(prevPoint)
                            pointFromBelow.add(point)

                        elif prevPoint in pointFromAbove:
                            pointFromAbove.remove(prevPoint)
                            pointFromAbove.add(point)

                if line1(xnew, ynew) < 0 and prevPoint in pointFromBelow: # Point is above the line
                    print('One Crossed Above')
                    print(point)
                    crossedAbove += 1
                    pointFromBelow.remove(prevPoint)

                if line2(xnew, ynew) > 0 and prevPoint in pointFromAbove: # Point is below the line
                    print('One Crossed Below')
                    print(point)
                    crossedBelow += 1
                    pointFromAbove.remove(prevPoint)


    for point in points:
        if point in pointFromBelow:
            cv2.circle(frame, point, 3, (255,0,255),6)
        elif point in pointFromAbove:
            cv2.circle(frame, point, 3, (0,255,255),6)
        else:
            cv2.circle(frame, point, 3, (0,0,255),6)
    cv2.line(frame, (0,300), (1920,880), (255, 0, 0), 4)
    cv2.line(frame, (0,500), (1920,1080), (255, 0, 0), 4)
    cv2.putText(frame,'People Going Above = '+str(crossedAbove),(1200,50), font, 1,(255,255,255),2,cv2.LINE_AA)
    cv2.putText(frame,'People Going Below = '+str(crossedBelow),(1200,100), font, 1,(255,255,255),2,cv2.LINE_AA)
    cv2.imshow('a',oldFgmask)
    cv2.imshow('frame',frame)
    out.write(frame)
    l = cv2.waitKey(1) & 0xff
    if l == 27:
        break
cap.release()
cv2.destroyAllWindows()

Answer 1

cap.read()返回False和空的frame。然后，您尝试在该frame上应用模糊处理，从而触发异常。仅当不为空时，才应处理框架。可能有几个原因会导致空框架：

设备1不可用（但我认为OpenCV在这种情况下会发布错误消息）
设备尚未准备好发送帧，因为它刚刚打开并仍在初始化
设备没有要返回的框架，在这种情况下，您应该稍等片刻，然后再试一次

我将从后面的内容开始，将cap.read()之后的所有内容放在if ret:语句下。

    while(1):
    pointInMiddle = set()
    prev = points
    points = set()
    ret, frame = cap.read()
    print(ret)
    print(frame)
    if ret:
        fgmask = frame
        fgmask = cv2.blur(frame, (10,10))
        fgmask = fgbg.apply(fgmask)
        fgmask = cv2.medianBlur(fgmask, 7)
        oldFgmask = fgmask.copy()
        contours, hierarchy = cv2.findContours(fgmask, cv2.RETR_EXTERNAL,1)
        ...

覆盆子Pi的乘客计数错误

1 个答案: