simple CV based detection for raspberry pi

piDetection.py

# import the necessary packages
import argparse
import datetime
import time
import cv2
from picamera.array import PiRGBArray
from picamera import PiCamera

# construct the argument parser and parse the arguments
ap = argparse.ArgumentParser()
ap.add_argument("-a", "--min-area", type=int, default = 200, help="minimum area size")
ap.add_argument("-c", "--cool-down", type=int, default = 10, help="the lowest tiem interval (in sec) between two images")
args = vars(ap.parse_args())
 

#load camera
# initialize the camera and grab a reference to the raw camera capture
camera = PiCamera()
camera.vflip = True
camera.resolution = (640, 480)
camera.framerate = 32
rawCapture = PiRGBArray(camera, size=(640, 480))


#init the background substractor
fgbg = cv2.BackgroundSubtractorMOG2(history = 1000, varThreshold = 100, bShadowDetection = False)

lastDetection = time.time()

# loop over the frames of the video
for frame in camera.capture_continuous(rawCapture, format="bgr", use_video_port=True):

        currentTime = time.time()
        frame = frame.array
 
        #resize, grayscale and blur
	gray = cv2.cvtColor(frame, cv2.COLOR_BGR2GRAY)
        #gray = cv2.resize(gray, (640, 480))
        ##gray = cv2.dilate(gray, None, iterations=2)
	gray = cv2.GaussianBlur(gray, (11, 11), 0)

        #bg substract method
        bg = fgbg.apply(gray, learningRate = 1.0/150)

        #addition stuff
        bg = cv2.dilate(bg, None, iterations=2)
        #bg = cv2.erode(bg, None, iterations=2)

	(cnts, _) = cv2.findContours(bg.copy(), cv2.RETR_EXTERNAL, cv2.CHAIN_APPROX_SIMPLE)

	# loop over the contours
	for c in cnts:
		# if the contour is too small, ignore it
		if cv2.contourArea(c) < args["min_area"]:
                        continue
 
		# compute the bounding box for the contour, draw it on the frame,
		# and update the text
		(x, y, w, h) = cv2.boundingRect(c)
		cv2.rectangle(frame, (x, y), (x + w, y + h), (0, 255, 0), 2)

                # save this image, if not already saved
                if lastDetection + args["cool_down"] < currentTime:
                        print "saving"
                        lastDetection = currentTime
                        nameString = "detected/" + time.ctime() + ".jpg"
                        cv2.imwrite(nameString, frame)

                        
        rawCapture.truncate(0)
        
        cv2.waitKey(1)