blocks|key|4499597|text|缺少XML或文件，或者指向它的路径不正确，或者create_capture路径不正确。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|4499598|opencv示例中的路径如下所示：|4499599|cascade_fn+=+args.get('--cascade',+"../../data/haarcascades/haarcascade_frontalface_alt.xml")
nested_fn++=+args.get('--nested-cascade',+"../../data/haarcascades/haarcascade_eye.xml")

cam+=+create_capture(video_src,+fallback='synth:bg=../data/lena.jpg:noise=0.05')|code-block|syntax|javascript|4499600|entityMap^0|0|0|0^^$0|@$1|2|3|4|5|6|7|K|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|L|8|@]|9|@]|A|$]]|$1|D|3|E|5|F|7|M|8|@]|9|@]|A|$G|H]]|$1|I|3|-4|5|6|7|N|8|@]|9|@]|A|$]]]|J|$]]

The XML or file is missing or the path to it is incorrect or the create_capture path is incorrect.

The paths in the opencv sample look like this:

<pre><code>cascade_fn = args.get('--cascade', "../../data/haarcascades/haarcascade_frontalface_alt.xml")
nested_fn = args.get('--nested-cascade', "../../data/haarcascades/haarcascade_eye.xml")

cam = create_capture(video_src, fallback='synth:bg=../data/lena.jpg:noise=0.05')
</code></pre>

blocks|key|4498744|text|我运行了同样的代码。这里有两件事需要注意。1.给出.xml文件的完整路径。2.最后给出一个按键事件指令。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|4498745|在最后添加以下代码块并运行您的文件，这对我很有效：|4498746|k+=+cv2.waitKey(0)
if+k+==+27:+++++++++#+wait+for+ESC+key+to+exit
++++cv2.destroyAllWindows()
elif+k+==+ord('s'):+#+wait+for+'s'+key+to+save+and+exit
++++cv2.imwrite('messigray.png',img)
++++cv2.destroyAllWindows()|code-block|syntax|javascript|4498747|例如，我的代码看起来像这样|4498748|import+numpy+as+np
import+cv2

face_cascade+=+cv2.CascadeClassifier('C:\\opencv\\build\\etc\\haarcascades\\haarcascade_frontalface_default.xml')
eye_cascade+=+cv2.CascadeClassifier('C:\\opencv\\build\\etc\\haarcascades\\haarcascade_eye.xml')

img+=+cv2.imread('lena.jpg')

gray+=+cv2.cvtColor(img,+cv2.COLOR_BGR2GRAY)

faces+=+face_cascade.detectMultiScale(gray,+1.3,+5)
#faces+=+face_cascade.detectMultiScale(gray)

for+(x,y,w,h)+in+faces:
++++cv2.rectangle(img,(x,y),(x%2Bw,y%2Bh),(255,0,0),2)
++++roi_gray+=+gray[y:y%2Bh,+x:x%2Bw]
++++roi_color+=+img[y:y%2Bh,+x:x%2Bw]
++++eyes+=+eye_cascade.detectMultiScale(roi_gray)
++++for+(ex,ey,ew,eh)+in+eyes:
++++++++cv2.rectangle(roi_color,(ex,ey),(ex%2Bew,ey%2Beh),(0,255,0),2)

cv2.imshow('img',img)

k+=+cv2.waitKey(0)
if+k+==+27:+++++++++#+wait+for+ESC+key+to+exit
++++cv2.destroyAllWindows()
elif+k+==+ord('s'):+#+wait+for+'s'+key+to+save+and+exit
++++cv2.imwrite('messigray.png',img)
++++cv2.destroyAllWindows()|4498749|我的输出如下所示：|4498750|​|4498751|📷|atomic|offset|length|4498752|4498753|entityMap|0|IMAGE|mutability|IMMUTABLE|imageUrl|https://ask.qcloudimg.com/http-save/yehe-900000/579cc582ca9bfdb51e306b2d06a952ca.png|imageAlt^0|0|0|0|0|0|0|0|0|1|0|0|0^^$0|@$1|2|3|4|5|6|7|15|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|16|8|@]|9|@]|A|$]]|$1|D|3|E|5|F|7|17|8|@]|9|@]|A|$G|H]]|$1|I|3|J|5|6|7|18|8|@]|9|@]|A|$]]|$1|K|3|L|5|F|7|19|8|@]|9|@]|A|$G|H]]|$1|M|3|N|5|6|7|1A|8|@]|9|@]|A|$]]|$1|O|3|P|5|6|7|1B|8|@]|9|@]|A|$]]|$1|Q|3|R|5|S|7|1C|8|@]|9|@$T|1D|U|1E|1|1F]]|A|$]]|$1|V|3|P|5|6|7|1G|8|@]|9|@]|A|$]]|$1|W|3|-4|5|6|7|1H|8|@]|9|@]|A|$]]]|X|$Y|$5|Z|10|11|A|$12|13|14|-4]]]]

I ran the same code. There are two things to note here.
1. Give the entire path of the .xml files.
2. Give a key press event instruction at the end.

Add this block of code at the end and run your file, worked for me:

<pre><code>k = cv2.waitKey(0)
if k == 27: # wait for ESC key to exit
 cv2.destroyAllWindows()
elif k == ord('s'): # wait for 's' key to save and exit
 cv2.imwrite('messigray.png',img)
 cv2.destroyAllWindows()
</code></pre>

For example, my code looked like 

<pre><code>import numpy as np
import cv2

face_cascade = cv2.CascadeClassifier('C:\\opencv\\build\\etc\\haarcascades\\haarcascade_frontalface_default.xml')
eye_cascade = cv2.CascadeClassifier('C:\\opencv\\build\\etc\\haarcascades\\haarcascade_eye.xml')

img = cv2.imread('lena.jpg')

gray = cv2.cvtColor(img, cv2.COLOR_BGR2GRAY)

faces = face_cascade.detectMultiScale(gray, 1.3, 5)
#faces = face_cascade.detectMultiScale(gray)

for (x,y,w,h) in faces:
 cv2.rectangle(img,(x,y),(x+w,y+h),(255,0,0),2)
 roi_gray = gray[y:y+h, x:x+w]
 roi_color = img[y:y+h, x:x+w]
 eyes = eye_cascade.detectMultiScale(roi_gray)
 for (ex,ey,ew,eh) in eyes:
 cv2.rectangle(roi_color,(ex,ey),(ex+ew,ey+eh),(0,255,0),2)

cv2.imshow('img',img)

k = cv2.waitKey(0)
if k == 27: # wait for ESC key to exit
 cv2.destroyAllWindows()
elif k == ord('s'): # wait for 's' key to save and exit
 cv2.imwrite('messigray.png',img)
 cv2.destroyAllWindows()
</code></pre>

My output looked like this:

<img src="https://i.stack.imgur.com/zbWYN.png" alt="ouput">

blocks|key|4498806|text|使用整个文件路径，并在xml文件路径中使用"\“而不是"\”。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|4498807|文件路径应如下所示：|4498808|face_cascade+=+cv2.CascadeClassifier('C:\\opencv\\build\\etc\\haarcascades\\haarcascade_frontalface_default.xml')|code-block|syntax|javascript|4498809|而不是：|4498810|cascade_fn+=+args.get('--cascade',+"..\..\data\haarcascades\haarcascade_frontalface_alt.xml")|4498811|entityMap^0|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|O|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|P|8|@]|9|@]|A|$]]|$1|D|3|E|5|F|7|Q|8|@]|9|@]|A|$G|H]]|$1|I|3|J|5|6|7|R|8|@]|9|@]|A|$]]|$1|K|3|L|5|F|7|S|8|@]|9|@]|A|$G|H]]|$1|M|3|-4|5|6|7|T|8|@]|9|@]|A|$]]]|N|$]]

Use the entire file path and use "\\" instead of "\" in the xml file path.

The file path should be as follows:

<pre><code>face_cascade = cv2.CascadeClassifier('C:\\opencv\\build\\etc\\haarcascades\\haarcascade_frontalface_default.xml')
</code></pre>

instead of: 

<pre><code>cascade_fn = args.get('--cascade', "..\..\data\haarcascades\haarcascade_frontalface_alt.xml")
</code></pre>

blocks|key|4499788|text|如果您使用的是Anaconda，则应该添加Anaconda路径。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|4499789|new_path+=+'C:/Users/.../Anaconda/Library/etc/haarcascades/'

face_cascade+=+cv2.CascadeClassifier(new_path+%2B+'haarcascade_frontalface_default.xml')|code-block|syntax|javascript|4499790|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|J|8|@]|9|@]|A|$E|F]]|$1|G|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|H|$]]

If you are using Anaconda you should add the Anaconda path.

<pre><code>new_path = 'C:/Users/.../Anaconda/Library/etc/haarcascades/'

face_cascade = cv2.CascadeClassifier(new_path + 'haarcascade_frontalface_default.xml')
</code></pre>

blocks|key|4499835|text|找不到您的XML文件。尝试使用绝对路径，如：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|4499836|/path/to/my/file+(Mac,+Linux)
C:\\path\\to\\my\\file+(Windows)|code-block|syntax|javascript|4499837|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|J|8|@]|9|@]|A|$E|F]]|$1|G|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|H|$]]

Your XML file was not found. Try using absolute paths like:

<pre><code>/path/to/my/file (Mac, Linux)
C:\\path\\to\\my\\file (Windows)
</code></pre>

blocks|key|4499878|text|当您没有定义XML文件的完整路径时，您可能会发现此类错误。如果您使用的是raspberrypi+3中的opencv3.1.0，请尝试此方法：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|4499879|faceCascade+=+cv2.CascadeClassifier('/home/pi/opencv-3.1.0/data/haarcascades/haarcascade_frontalface_default.xml')|offset|length|style|CODE|4499880|entityMap^0|0|0|36|0^^$0|@$1|2|3|4|5|6|7|J|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|K|8|@$D|L|E|M|F|G]]|9|@]|A|$]]|$1|H|3|-4|5|6|7|N|8|@]|9|@]|A|$]]]|I|$]]

You may find such kind of errors when you did not define the complete path of your XML file.
Try this one if you are using opencv3.1.0 in raspberrypi 3:
<code>faceCascade = cv2.CascadeClassifier('/home/pi/opencv-3.1.0/data/haarcascades/haarcascade_frontalface_default.xml')</code>

blocks|key|4498908|text|可能face_cascade是空的。您可以通过键入以下命令来检查变量是否为空：|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|4498909|face_cascade.empty()|code-block|syntax|javascript|4498910|如果它是空的，你将得到True，这意味着你的文件在你提到的路径中不可用。尝试添加xml文件的完整路径，如下所示：|4498911|r'D:\folder+Name\haarcascade_frontalface_default.xml'|4498912|entityMap^0|2|C|0|0|B|4|0|0^^$0|@$1|2|3|4|5|6|7|Q|8|@$9|R|A|S|B|C]]|D|@]|E|$]]|$1|F|3|G|5|H|7|T|8|@]|D|@]|E|$I|J]]|$1|K|3|L|5|6|7|U|8|@$9|V|A|W|B|C]]|D|@]|E|$]]|$1|M|3|N|5|H|7|X|8|@]|D|@]|E|$I|J]]|$1|O|3|-4|5|6|7|Y|8|@]|D|@]|E|$]]]|P|$]]

Probably the <code>face_cascade</code> is empty. You can check if the variable is empty or not by typing following command:

<pre><code>face_cascade.empty()
</code></pre>

If it is empty you will get <code>True</code> and this means your file is not available in the path you mentioned. 
Try to add complete path of xml file as follows:

<pre><code>r'D:\folder Name\haarcascade_frontalface_default.xml'
</code></pre>

blocks|key|4499905|text|在安装了自制软件的OSX上，opencv文件夹的完整路径应该可以工作：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|4499906|face_cascade+=+cv2.CascadeClassifier('/usr/local/Cellar/opencv/3.4.0_1/share/OpenCV/haarcascades/haarcascade_frontalface_default.xml')
eye_cascade+=+cv2.CascadeClassifier('/usr/local/Cellar/opencv/3.4.0_1/share/OpenCV/haarcascades/haarcascade_eye.xml')|code-block|syntax|javascript|4499907|注意路径中的版本号。|4499908|entityMap^0|0|0|0^^$0|@$1|2|3|4|5|6|7|K|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|L|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|M|8|@]|9|@]|A|$]]|$1|I|3|-4|5|6|7|N|8|@]|9|@]|A|$]]]|J|$]]

On OSX with a homebrew install the full path to the opencv folder should work:

<pre><code>face_cascade = cv2.CascadeClassifier('/usr/local/Cellar/opencv/3.4.0_1/share/OpenCV/haarcascades/haarcascade_frontalface_default.xml')
eye_cascade = cv2.CascadeClassifier('/usr/local/Cellar/opencv/3.4.0_1/share/OpenCV/haarcascades/haarcascade_eye.xml')
</code></pre>

Take care of the version number in the path.

blocks|key|4499919|text|错误可能是由于未正确加载所需的xml文件所致。使用ur+OS的搜索引擎搜索文件haarcascade_frontalface_default.xml，获取完整路径，并将其作为参数以字符串形式提供给cv2.CascadeClassifier|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|4499920|entityMap^0|13|Z|2Q|L|0^^$0|@$1|2|3|4|5|6|7|H|8|@$9|I|A|J|B|C]|$9|K|A|L|B|C]]|D|@]|E|$]]|$1|F|3|-4|5|6|7|M|8|@]|D|@]|E|$]]]|G|$]]

the error may be due to, the required xml files has not been loaded properly. Search for the file <code>haarcascade_frontalface_default.xml</code> by using the search engine of ur OS get the full path and put it as the argument to <code>cv2.CascadeClassifier</code> as string

blocks|key|4499018|text|出现此错误的原因是缺少xml文件或xml文件的路径不正确。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|4499019|请尝试以下代码，|4499020|import+numpy+as+np
import+cv2

face_cascade+=+cv2.CascadeClassifier('haarcascade_frontalface_default.xml')
eye_cascade+=+cv2.CascadeClassifier('haarcascade_eye.xml')

cap+=+cv2.VideoCapture(0)

while+1:
++++ret,+img+=+cap.read()
++++gray+=+cv2.cvtColor(img,+cv2.COLOR_BGR2GRAY)
++++faces+=+face_cascade.detectMultiScale(gray,+1.3,+5)

++++for+(x,y,w,h)+in+faces:
++++++++cv2.rectangle(img,(x,y),(x%2Bw,y%2Bh),(255,0,0),2)
++++++++roi_gray+=+gray[y:y%2Bh,+x:x%2Bw]
++++++++roi_color+=+img[y:y%2Bh,+x:x%2Bw]

++++++++eyes+=+eye_cascade.detectMultiScale(roi_gray)
++++++++for+(ex,ey,ew,eh)+in+eyes:
++++++++++++cv2.rectangle(roi_color,(ex,ey),(ex%2Bew,ey%2Beh),(0,255,0),2)

++++cv2.imshow('img',img)
++++k+=+cv2.waitKey(30)+&+0xff
++++if+k+==+27:
++++++++break

cap.release()
cv2.destroyAllWindows()|code-block|syntax|javascript|4499021|entityMap^0|0|0|0^^$0|@$1|2|3|4|5|6|7|K|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|L|8|@]|9|@]|A|$]]|$1|D|3|E|5|F|7|M|8|@]|9|@]|A|$G|H]]|$1|I|3|-4|5|6|7|N|8|@]|9|@]|A|$]]]|J|$]]

The error occurs due to missing of xml files or incorrect path of xml file. 

Please try the following code,

<pre><code>import numpy as np
import cv2

face_cascade = cv2.CascadeClassifier('haarcascade_frontalface_default.xml')
eye_cascade = cv2.CascadeClassifier('haarcascade_eye.xml')

cap = cv2.VideoCapture(0)

while 1:
 ret, img = cap.read()
 gray = cv2.cvtColor(img, cv2.COLOR_BGR2GRAY)
 faces = face_cascade.detectMultiScale(gray, 1.3, 5)

 for (x,y,w,h) in faces:
 cv2.rectangle(img,(x,y),(x+w,y+h),(255,0,0),2)
 roi_gray = gray[y:y+h, x:x+w]
 roi_color = img[y:y+h, x:x+w]

 eyes = eye_cascade.detectMultiScale(roi_gray)
 for (ex,ey,ew,eh) in eyes:
 cv2.rectangle(roi_color,(ex,ey),(ex+ew,ey+eh),(0,255,0),2)

 cv2.imshow('img',img)
 k = cv2.waitKey(30) &amp; 0xff
 if k == 27:
 break

cap.release()
cv2.destroyAllWindows()
</code></pre>

blocks|key|4499953|text|请不要复制粘贴xml文件的内容，因为一旦将其粘贴到记事本，它将被保存为%25s文本文件。所以直接从给定源下载文件。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|4499954|entityMap^0|0^^$0|@$1|2|3|4|5|6|7|D|8|@]|9|@]|A|$]]|$1|B|3|-4|5|6|7|E|8|@]|9|@]|A|$]]]|C|$]]

Please do not copy paste the content of xml file, because once you paste it to notepad it will be saved a s text file. So directly download the file from the given source.

blocks|key|4499974|text|"\Anaconda3\Lib\site-packages\cv2\data\“我在Anaconda的以下路径中找到了xml文件|type|unstyled|depth|inlineStyleRanges|entityRanges|data|4499975|entityMap^0|0^^$0|@$1|2|3|4|5|6|7|D|8|@]|9|@]|A|$]]|$1|B|3|-4|5|6|7|E|8|@]|9|@]|A|$]]]|C|$]]

"\Anaconda3\Lib\site-packages\cv2\data\" I found the xml file in this path for Anaconda

blocks|key|4499996|text|我在opencv-python上也遇到了同样的问题，我使用了一个虚拟环境。如果是您的情况，您应该在以下位置找到xml文件：|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|4499997|/home/username/virtual_environment/lib/python3.5/site-packages/cv2/data/haarcascade_frontalface_default.xml|4499998|/home/username/virtual_environment/lib/python3.5/site-packages/cv2/data/haarcascade_eye.xml|4499999|请确保您使用的是绝对路径。否则，它就不会起作用。|4500000|entityMap^0|2|D|1J|3|0|0|2Z|0|0|2J|0|0^^$0|@$1|2|3|4|5|6|7|N|8|@$9|O|A|P|B|C]|$9|Q|A|R|B|C]]|D|@]|E|$]]|$1|F|3|G|5|6|7|S|8|@$9|T|A|U|B|C]]|D|@]|E|$]]|$1|H|3|I|5|6|7|V|8|@$9|W|A|X|B|C]]|D|@]|E|$]]|$1|J|3|K|5|6|7|Y|8|@]|D|@]|E|$]]|$1|L|3|-4|5|6|7|Z|8|@]|D|@]|E|$]]]|M|$]]

I had the same problem with <code>opencv-python</code> and I used a virtual environment.
If it's your case, you should find the <code>xml</code> files at:

<code>/home/username/virtual_environment/lib/python3.5/site-packages/cv2/data/haarcascade_frontalface_default.xml</code>

<code>/home/username/virtual_environment/lib/python3.5/site-packages/cv2/data/haarcascade_eye.xml</code>

Please be sure that you're using the absolute path. Otherwise, it won't work.

blocks|key|4500006|text|无需更改代码|type|unstyled|depth|inlineStyleRanges|entityRanges|data|4500007|下载该.xml文件，然后将该文件的路径|4500008|它将解决错误(100%25)|4500009|entityMap^0|0|0|0^^$0|@$1|2|3|4|5|6|7|H|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|I|8|@]|9|@]|A|$]]|$1|D|3|E|5|6|7|J|8|@]|9|@]|A|$]]|$1|F|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|G|$]]

no need to change the code 

download that .xml file , then put the path of that file 

it will solve the error (100%)

blocks|key|4500023|text|此错误表示找不到XML文件。该库需要您向其传递完整路径，即使您可能只使用了OpenCV库附带的文件。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|4500024|您可以使用内置的pkg_resources+module自动为您确定这一点。下面的代码在加载cv2模块的位置查找文件的完整路径：|offset|length|style|CODE|4500025|import+pkg_resources
haar_xml+=+pkg_resources.resource_filename(
++++'cv2',+'data/haarcascade_frontalface_default.xml')|code-block|syntax|javascript|4500026|对我来说，这是'/Users/andrew/.local/share/virtualenvs/foo-_b9W43ee/lib/python3.7/site-packages/cv2/data/haarcascade_frontalface_default.xml'；你的肯定是不同的。让python的pkg_resources库来解决这个问题。|4500027|classifier+=+cv2.CascadeClassifier(haar_xml)
faces+=+classifier.detectMultiScale(frame)|4500028|成功！|4500029|entityMap|0|LINK|mutability|MUTABLE|url|https://setuptools.readthedocs.io/en/latest/pkg_resources.html#resource-extraction^0|0|8|D|1A|3|8|K|0|0|0|7|3I|47|D|0|0|0^^$0|@$1|2|3|4|5|6|7|10|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|11|8|@$D|12|E|13|F|G]|$D|14|E|15|F|G]]|9|@$D|16|E|17|1|18]]|A|$]]|$1|H|3|I|5|J|7|19|8|@]|9|@]|A|$K|L]]|$1|M|3|N|5|6|7|1A|8|@$D|1B|E|1C|F|G]|$D|1D|E|1E|F|G]]|9|@]|A|$]]|$1|O|3|P|5|J|7|1F|8|@]|9|@]|A|$K|L]]|$1|Q|3|R|5|6|7|1G|8|@]|9|@]|A|$]]|$1|S|3|-4|5|6|7|1H|8|@]|9|@]|A|$]]]|T|$U|$5|V|W|X|A|$Y|Z]]]]

This error means that the XML file could not be found. The library needs you to pass it the full path, even though you’re probably just using a file that came with the OpenCV library.

You can use the built-in <a href="https://setuptools.readthedocs.io/en/latest/pkg_resources.html#resource-extraction" rel="noreferrer"><code>pkg_resources</code> module</a> to automatically determine this for you. The following code looks up the full path to a file inside wherever the <code>cv2</code> module was loaded from:

<pre><code>import pkg_resources
haar_xml = pkg_resources.resource_filename(
 'cv2', 'data/haarcascade_frontalface_default.xml')
</code></pre>

For me this was <code>'/Users/andrew/.local/share/virtualenvs/foo-_b9W43ee/lib/python3.7/site-packages/cv2/data/haarcascade_frontalface_default.xml'</code>; yours is guaranteed to be different. Just let python’s <code>pkg_resources</code> library figure it out.

<pre><code>classifier = cv2.CascadeClassifier(haar_xml)
faces = classifier.detectMultiScale(frame)
</code></pre>

Success!

blocks|key|4499164|text|我也有同样的问题。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|4499165|我不需要下载任何其他东西来解决这个问题。我需要的CV2都有了。|4499166|我使用了cv2提供的一个属性，而不是尝试找出.xml文件的位置并硬编码这些值。|offset|length|style|CODE|4499167|来自运维|4499168|face_cascade+=+cv2.CascadeClassifier('haarcascade_frontalface_default.xml')
eye_cascade+=+cv2.CascadeClassifier('haarcascade_eye.xml')|code-block|syntax|javascript|4499169|变成了|4499170|face_cascade+=+cv2.CascadeClassifier(cv2.data.haarcascades+%2B+'haarcascade_frontalface_default.xml')
eye_cascade+=+cv2.CascadeClassifier(cv2.data.haarcascades+%2B+'haarcascade_eye.xml')|4499171|entityMap^0|0|0|M|4|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|W|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|X|8|@]|9|@]|A|$]]|$1|D|3|E|5|6|7|Y|8|@$F|Z|G|10|H|I]]|9|@]|A|$]]|$1|J|3|K|5|6|7|11|8|@]|9|@]|A|$]]|$1|L|3|M|5|N|7|12|8|@]|9|@]|A|$O|P]]|$1|Q|3|R|5|6|7|13|8|@]|9|@]|A|$]]|$1|S|3|T|5|N|7|14|8|@]|9|@]|A|$O|P]]|$1|U|3|-4|5|6|7|15|8|@]|9|@]|A|$]]]|V|$]]

I had the same issue.

I didn't need to download anything else to solve this. CV2 had everything I needed. 

Instead of trying to figure out where the <code>.xml</code> files are and hard coding the values, I used a property given by cv2. 

From OP

<pre><code>face_cascade = cv2.CascadeClassifier('haarcascade_frontalface_default.xml')
eye_cascade = cv2.CascadeClassifier('haarcascade_eye.xml')
</code></pre>

Becomes 

<pre><code>face_cascade = cv2.CascadeClassifier(cv2.data.haarcascades + 'haarcascade_frontalface_default.xml')
eye_cascade = cv2.CascadeClassifier(cv2.data.haarcascades + 'haarcascade_eye.xml')
</code></pre>

blocks|key|4500077|text|我遇到了同样的问题。但写的位置是正确的。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|4500078|face_cascade+=+cv2.CascadeClassifier('./model/haarcascade_frontalface_default.xml')|code-block|syntax|javascript|4500079|我想我需要声明完整的路径来删除错误。|4500080|face_cascade+=+cv2.CascadeClassifier('C:/pythonScript/Facial-Emotion-Detection/model/haarcascade_frontalface_default.xml')|4500081|entityMap^0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|M|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|N|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|O|8|@]|9|@]|A|$]]|$1|I|3|J|5|D|7|P|8|@]|9|@]|A|$E|F]]|$1|K|3|-4|5|6|7|Q|8|@]|9|@]|A|$]]]|L|$]]

I ran into the same problem. but wrote the correct location.

<pre><code>face_cascade = cv2.CascadeClassifier('./model/haarcascade_frontalface_default.xml')
</code></pre>

I figured out that i need to declare the full path to remove the error.

<pre><code>face_cascade = cv2.CascadeClassifier('C:/pythonScript/Facial-Emotion-Detection/model/haarcascade_frontalface_default.xml')
</code></pre>

blocks|key|4500103|text|我在其他答案中发现了这一点，但当我添加这两个答案时，最终对我起作用了。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|4500104|import+cv2
from+matplotlib+import+pyplot+as+plt
import+numpy+as+np
face_cascade+=+cv2.CascadeClassifier(cv2.data.haarcascades+%2B+"haarcascade_frontalface_default.xml")
eye_cascade+=+cv2.CascadeClassifier(cv2.data.haarcascades+%2B+"haarcascade_eye.xml")

img+=+cv2.imread('image1.jpg')
gray+=+cv2.cvtColor(img,+cv2.COLOR_BGR2GRAY)
faces+=+face_cascade.detectMultiScale(gray,+1.3,+5)|code-block|syntax|javascript|4500105|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|J|8|@]|9|@]|A|$E|F]]|$1|G|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|H|$]]

I found this in some other answer but eventually worked for me when I added the two answers.
<pre><code>import cv2
from matplotlib import pyplot as plt
import numpy as np
face_cascade = cv2.CascadeClassifier(cv2.data.haarcascades + &quot;haarcascade_frontalface_default.xml&quot;)
eye_cascade = cv2.CascadeClassifier(cv2.data.haarcascades + &quot;haarcascade_eye.xml&quot;)

img = cv2.imread('image1.jpg')
gray = cv2.cvtColor(img, cv2.COLOR_BGR2GRAY)
faces = face_cascade.detectMultiScale(gray, 1.3, 5)
</code></pre>

blocks|key|4499261|text|我也遇到过类似的问题。似乎改正XML的路径可以消除这个错误。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|4499262|entityMap^0|0^^$0|@$1|2|3|4|5|6|7|D|8|@]|9|@]|A|$]]|$1|B|3|-4|5|6|7|E|8|@]|9|@]|A|$]]]|C|$]]

I faced a similar issue. It seems correcting the path to XML makes this error to go away.

blocks|key|4500136|text|似乎是文件路径问题。我像这样修改了代码，它起作用了。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|4500137|haar_face_filename+=+"D:\Sandbox\Github\Faces\haar_face.xml"
haar_cascade+=+cv.CascadeClassifier(haar_face_filename)|code-block|syntax|javascript|4500138|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|J|8|@]|9|@]|A|$E|F]]|$1|G|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|H|$]]

It seems to be file path issue. I changed code like this and it worked.
<pre class="lang-py prettyprint-override"><code>haar_face_filename = &quot;D:\Sandbox\Github\Faces\haar_face.xml&quot;
haar_cascade = cv.CascadeClassifier(haar_face_filename)
</code></pre>

blocks|key|4500157|text|我遇到了同样的问题，并试图在一个springboot应用程序中使用open+cv，其中我的xml文件和图像都在resources文件夹中。尝试提供从src或C:\a\b.xml之类的绝对路径开始的路径不起作用。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|4500158|使用项目根路径动态创建文件路径。|4500159|String+classifierPath+=+System.getProperty("user.dir")+%2B+"/src/main/resources/haarcascades/haarcascade_frontalface.xml";

//+similarly+for+image+paths|code-block|syntax|javascript|4500160|entityMap^0|22|3|26|A|0|0|0^^$0|@$1|2|3|4|5|6|7|O|8|@$9|P|A|Q|B|C]|$9|R|A|S|B|C]]|D|@]|E|$]]|$1|F|3|G|5|6|7|T|8|@]|D|@]|E|$]]|$1|H|3|I|5|J|7|U|8|@]|D|@]|E|$K|L]]|$1|M|3|-4|5|6|7|V|8|@]|D|@]|E|$]]]|N|$]]

I had the same issue and was trying to use open cv in a springboot application where my xml files and images are in resources folder.
Trying to give path starting from <code>src</code> or a absolute path like <code>C:\a\b.xml</code> did not work.
Creating the file path dynamically with project root path worked.
<pre><code>String classifierPath = System.getProperty(&quot;user.dir&quot;) + &quot;/src/main/resources/haarcascades/haarcascade_frontalface.xml&quot;;

// similarly for image paths
</code></pre>

blocks|key|4499302|text|路径需要以/开头，例如。/file.xml。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|4499303|entityMap^0|5|1|C|9|0^^$0|@$1|2|3|4|5|6|7|H|8|@$9|I|A|J|B|C]|$9|K|A|L|B|C]]|D|@]|E|$]]|$1|F|3|-4|5|6|7|M|8|@]|D|@]|E|$]]]|G|$]]

Path needs to start with <code>/</code>, eg. <code>/file.xml</code>.

I'm trying to learn cv2 in python 2.7, but when I run my code, in the specific part of it:

<pre><code>face_cascade = cv2.CascadeClassifier('haarcascade_frontalface_default.xml')
 eye_cascade = cv2.CascadeClassifier('haarcascade_eye.xml')


img = cv2.imread('2015-05-27-191152.jpg')
gray = cv2.cvtColor(img, cv2.COLOR_BGR2GRAY)

faces = face_cascade.detectMultiScale(gray, 1.3, 5)
for (x,y,w,h) in faces:
 img = cv2.rectangle(img,(x,y),(x+w,y+h),(255,0,0),2)
</code></pre>

it returns this:

<pre><code>File "face_detection.py", line 11, in &lt;module&gt;
 faces = face_cascade.detectMultiScale(gray, 1.3, 5)
cv2.error: /home/arthurckl/Desktop/opencv-3.0.0-rc1/modules/objdetect/src/cascadedetect.cpp:1595: error: (-215) !empty() in function detectMultiScale
</code></pre>

I tried to search the answer here but the best i could find is that I must be loading the face_cascade the wrong way... Any help?

error: (-215) !empty() in function detectMultiScale

我正在尝试学习Python2.7中的cv2，但是当我运行我的代码时，在它的特定部分：face_cascade = cv2.CascadeClassifier('haarcascade_frontalface_default.xml') eye_cascade = cv2.CascadeClassifier('haarc...

问错误：(-215)！函数detectMultiScale中的empty()
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