我已经看了很多遍了，但是OpenCV中的detectMultiScale总是出现同样的错误

Question

Traceback (most recent call last):
  File "/Users/jadalada/Documents/GitHub/allTests/OpenCV (Py)/VCV.py", line 14, in <module>
    faces = faceCascade.detectMultiScale(gray, scaleFactor=1.5, minNeighbors=5)
cv2.error: OpenCV(4.1.0) /Users/travis/build/skvark/opencv-python/opencv/modules/objdetect/src/cascadedetect.cpp:1658: error: (-215:Assertion failed) !empty() in function

import numpy as np
import cv2 as cv

faceCascade = cv.CascadeClassifier('Casscades/haarcascade_frontalface_default.xml')
eyeCascade = cv.CascadeClassifier('Casscades/haarcascade_eye.xml')
smileCascade = cv.CascadeClassifier('Casscades/haarcascade_smile.xml')

cap = cv.VideoCapture(0)

while(True):
    ret, frame = cap.read()
    gray = cv.cvtColor(frame, cv.COLOR_BGR2GRAY)

    faces = faceCascade.detectMultiScale(gray, scaleFactor=1.5, minNeighbors=5)
    eyes = eyeCascade.detectMultiScale(gray, scaleFactor=1.5, minNeighbors=5)
    smile = smileCascade.detectMultiScale(gray, scaleFactor=1.5, minNeighbors=5)

我不知道为什么会发生这种情况，因为在另一个完全相同的python文件中，对于同样的代码，它可以完美地工作

import numpy as np
import cv2 as cv

faceCascade = cv.CascadeClassifier('Casscades/haarcascade_frontalface_default.xml')
eyeCascade = cv.CascadeClassifier('Casscades/haarcascade_eye.xml')
smileCascade = cv.CascadeClassifier('Casscades/haarcascade_smile.xml')

cap = cv.VideoCapture(0)

while(True):
    ret, frame = cap.read()
    gray = cv.cvtColor(frame, cv.COLOR_BGR2GRAY)

    faces = faceCascade.detectMultiScale(gray, scaleFactor=1.5, minNeighbors=5)
    eyes = eyeCascade.detectMultiScale(gray, scaleFactor=1.5, minNeighbors=5)
    smile = smileCascade.detectMultiScale(gray, scaleFactor=1.5, minNeighbors=5)

这是另一个文件中完全相同的代码，运行完美，没有错误

Answer 1

错误很可能意味着级联分类器没有正确实例化。用途：

faceCascade.empty()

检查分类器是否正确实例化。如果返回true，则
1-xml文件路径不正确。
2-您的xml文件不正确
3-由于某种原因无法加载xml文件

如果您确定文件和路径正确，请尝试再次加载：

faceCascade.load('PATH_TO_XML')