I noticed something very odd in trying a motion detector for Raspberry Pi:
Removing the camera logging from the script, makes it use almost 0 CPU:
#from gpiozero import MotionSensor #import cv2 from datetime import datetime from time import sleep #camera = cv2.VideoCapture(0) #pir = MotionSensor(4, queue_len=2, sample_rate=2, threshold=0.5) import RPi.GPIO as GPIO GPIO.setmode(GPIO.BCM) PIR_PIN = 4 GPIO.setup(PIR_PIN, GPIO.IN) while True: sleep(1) if GPIO.input(PIR_PIN): print( "detected!") filename = 'motionpics/' + datetime.now().strftime("%Y-%m-%d_%H.%M.%S.jpg") #ret, frame = camera.read() #cv2.imwrite(filename, frame) #camera.release() #pir.wait_for_no_motion() However, uncommenting just one line - the import cv2, makes this script go to 300% CPU Usage!!
What is wrong with OpenCV and why can't I even start to use it to grab usb camera images without it using a bunch of cpu, and wearing down the battery?
2 Answers
Answers 1
Hmmmm, if I am not mistaken opencv needs numpy right? Could you try the following:
$ sudo apt-get install libatlas3-base $ sudo update-alternatives --config libblas.so.3 choose the libatlas option
$ sudo update-alternatives --config liblapack.so.3 choose the libatlas option
$ sudo aptitude purge libopenblas-{base,dev} Answers 2
I can confirm that Giannis' answer is correct. I just performed the steps listed in his answer and am able to import cv2 in python 3.4 without the high cpu usage. So at least there is that. I am able to grab a frame and display an image. This works for my use case.
I did notice however that during the aforementioned steps, libtiff5, wolfram, and several other libraries were uninstalled.
If you need these libraries and applications (I do not have a full list at the moment) I would reccomend temporarily NOT performing
Sudo apt-get dist-upgrade
And
Sudo rpi-update
At this time, and remain at raspbian jessie. This is just out of my personal experience.
EDIT:
Also I would like to add that Giannis was right, this is seemingly a numpy issue, and can easily be tested by simply:
going on your Raspberry Pi3's desktop->Start Menu->Code->Python 3; type "import numpy" (without quotes).
You should see your cpu usage go through the roof. This is a way of telling that you are eligible to have this fix work.
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