cv2.error: OpenCV(4.1.0) /io/opencv/modules/core/src/persistence.cpp:2046: error: (-215:Assertion failed) isMap() in function 'operator[]'

[leijuzi]

i got this error

[pjckoch]

I experience the same error with:

opencv-python==4.1.0.25
opencv-contrib-python==4.1.0.25

when running

fishface = cv2.face.FisherFaceRecognizer_create()
fishface.read("myxml.xml")

[mickey9801]

Same error with self compiled opencv 4.1.1 and opencv-contrib 4.1.1

The error:

(cv) pi@rpi401b:~/Documents/Python Projects/opencv/facelock $ python3 detector_webcam.py 
detector_webcam.py:23: RuntimeWarning: This channel is already in use, continuing anyway.  Use GPIO.setwarnings(False) to disable warnings.
  GPIO.setup(relayPin, GPIO.OUT)
Traceback (most recent call last):
  File "detector_webcam.py", line 44, in <module>
    recognizer.read(fname) # load() for createLBPHFaceRecognizer()
cv2.error: OpenCV(4.1.1) /home/pi/opencv/modules/core/src/persistence.cpp:2046: error: (-215:Assertion failed) isMap() in function 'operator[]'

The code I ran:

import cv2
import os
import sqlite3
import RPi.GPIO as GPIO
import time

# Connect SQLite3 database
conn = sqlite3.connect('database.db')
db = conn.cursor()

# Assign the training data file
fname = "recognizer/trainingData.yml"
if not os.path.isfile(fname):
    print("Please train the data first")
    exit(0)

# Setup GPIO for unlock LED
relayPin = 26
GPIO.setmode(GPIO.BCM)
GPIO.setup(relayPin, GPIO.OUT)
GPIO.output(relayPin, 0)

lastDetectedAt = 0
detectInterval = 5
lastUnlockedAt = 0
unlockDuration = 5

# Font used for display
font = cv2.FONT_HERSHEY_SIMPLEX

# Connect to video source
vSource = 0 # first USB webcam
vStream = cv2.VideoCapture(vSource)

# Setup Classifier for detect face
faceCascade = cv2.CascadeClassifier("haarcascade_frontalface_default.xml")
# Setup LBPH recognizer for face recognition
recognizer = cv2.face.LBPHFaceRecognizer_create()
# Load training data
recognizer.read(fname)

while vStream.isOpened():
    # Turn off unlock LED when timeout
    if time.time() - lastUnlockedAt > unlockDuration:
        GPIO.output(relayPin, 0)
    
    ok, frame = vStream.read() # Read frame
    if not ok: break
    
    timeElapsed = time.time() - lastDetectedAt
    if timeElapsed > 1./detectInterval:
        lastDetectedAt = time.time()
        
        # Detect face
        gray = cv2.cvtColor(frame, cv2.COLOR_BGR2GRAY)
        faces = faceCascade.detectMultiScale(gray, scaleFactor = 1.1, minNeighbors = 2)
        
        for (x, y, w, h) in faces:
            # Try to recognize the face a
            roiGray = gray[y:y+h, x:x+w]
            id_, conf = recognizer.predict(roiGray)
            print(id_, conf)
            
            # If recognized face has enough confident (<= 70),
            # retrieve the user name from database,
            # draw a rectangle around the face,
            # print the name of the user and
            # light up the unlock LED for 5 secord
            if conf <= 70:
                cv2.rectangle(frame, (x, y), (x+w, y+h), (0, 255, 0), 2)
                # retrieve user name from database
                db.execute("SELECT `name` FROM `users` WHERE `id` = (?);", (id_,))
                result = db.fetchall()
                name = result[0][0]
                
                GPIO.output(relayPin, 1) # Unlock
                lastUnlockedAt = time.time()
                print("[Unlock] " + str(id_) + ":" + name + " (" + str(conf) + ")")
                cv2.putText(frame, name, (x+2,y+h-5), font, 1, (150,255,0), 2)
            else:
                cv2.rectangle(frame, (x, y), (x+w, y+h), (0, 0, 255), 2)
                GPIO.output(relayPin, 0) # Lock the door if not enough confident
        
    cv2.imshow("Face Recognizer", frame)
    
    # Press ESC to quit the program
    key = cv2.waitKey(1) & 0xff
    if key == 27 or key == ord('q'):
        break

# Clean up
vStream.release()
conn.close()
cv2.destroyAllWindows()
GPIO.cleanup()
print("END")

[Futura9000]

Same error for me:

Ubuntu 18.04.3 LTS
Python 3.6.8
OpenCV 4.1.1
OpenCV Contrib: 4.1.1.26 (from sudo pip3 install opencv-contrib-python)

When using:

recognizer = cv2.face.LBPHFaceRecognizer_create()
recognizer.read(fname)

[mickey9801]

Finally I resolve the problem after retrain.

[Futura9000]

Finally I resolve the problem after retrain.

same for me!

[royalluckyboy]

how you can solve this problem? @mickey9801

[mickey9801]

how you can solve this problem? @mickey9801

Just retrain and it will work. @royalluckyboy

[mickey9801]

Retrain with the dataset and generate a new xml file. @royalluckyboy

[NitiKaur]

How to retrain it to generate the xml file? @mickey9801

[libni7erez]

Perdón, como hago para Re entrenar, soy nuevo en esto. Pueden ayudarme?