#Coding4Fun – How to control your #drone with 20 lines of code! (10/N)

Hi!

Back to some drone posts! I was kind of busy during the last weeks and now I can get back to write about the drone.

OK, in the last posts I described how to connect and work with the drone camera feed using OpenCV. Now with 2 extra lines of code we can also detect faces. Let’s take a look at the final sample.

In the previous image we can see 2 camera feeds. My computer webcam, where you can see how I hold the drone with the drone camera pointing to my face. And the drone camera feed, presented using OpenCV and drawing a frame over each detected face.

Let’s share some code insights:

• As usual, I resize the camera feed to 320 x 240
• The average processing time is between 40 and 70 FPS
• I use a haar cascade classifier to detect the faces in each frame

Note: I need to write about Haar Cascades as part of my face detection post series.

	# Bruno Capuano
	# detect faces using haar cascades from https://github.com/opencv/opencv/tree/master/data/haarcascades
	# enable drone video camera
	# display video camera using OpenCV
	# display FPS
	# detect faces
	import cv2
	import socket
	import time
	import threading
	def receiveData():
	global response
	while True:
	try:
	response, _ = clientSocket.recvfrom(1024)
	except:
	break
	def readStates():
	global battery
	while True:
	try:
	response_state, _ = stateSocket.recvfrom(256)
	if response_state != 'ok':
	response_state = response_state.decode('ASCII')
	list = response_state.replace(';', ':').split(':')
	battery = int(list[21])
	except:
	break
	def sendCommand(command):
	global response
	timestamp = int(time.time() * 1000)
	clientSocket.sendto(command.encode('utf-8'), address)
	while response is None:
	if (time.time() * 1000) – timestamp > 5 * 1000:
	return False
	return response
	def sendReadCommand(command):
	response = sendCommand(command)
	try:
	response = str(response)
	except:
	pass
	return response
	def sendControlCommand(command):
	response = None
	for i in range(0, 5):
	response = sendCommand(command)
	if response == 'OK' or response == 'ok':
	return True
	return False
	# ———————————————–
	# Main program
	# ———————————————–
	# connection info
	UDP_IP = '192.168.10.1'
	UDP_PORT = 8889
	last_received_command = time.time()
	STATE_UDP_PORT = 8890
	address = (UDP_IP, UDP_PORT)
	response = None
	response_state = None
	clientSocket = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
	clientSocket.bind(('', UDP_PORT))
	stateSocket = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
	stateSocket.bind(('', STATE_UDP_PORT))
	# start threads
	recThread = threading.Thread(target=receiveData)
	recThread.daemon = True
	recThread.start()
	stateThread = threading.Thread(target=readStates)
	stateThread.daemon = True
	stateThread.start()
	# connect to drone
	response = sendControlCommand("command")
	print(f'command response: {response}')
	response = sendControlCommand("streamon")
	print(f'streamon response: {response}')
	# drone information
	battery = 0
	# enable face detection
	face_cascade = cv2.CascadeClassifier('haarcascade_frontalface_default.xml')
	# open UDP
	print(f'opening UDP video feed, wait 2 seconds ')
	videoUDP = 'udp://192.168.10.1:11111'
	cap = cv2.VideoCapture(videoUDP)
	time.sleep(2)
	# open
	i = 0
	while True:
	i = i + 1
	start_time = time.time()
	try:
	_, frameOrig = cap.read()
	frame = cv2.resize(frameOrig, (320, 240))
	gray = cv2.cvtColor(frame, cv2.COLOR_BGR2GRAY)
	faces = face_cascade.detectMultiScale(gray, 1.3, 5)
	for (top, right, bottom, left) in faces:
	cv2.rectangle(frame,(top,right),(top+bottom,right+left),(0,0,255),2)
	# display fps
	if (time.time() – start_time ) > 0:
	fpsInfo = "FPS: " + str(1.0 / (time.time() – start_time)) # FPS = 1 / time to process loop
	font = cv2.FONT_HERSHEY_DUPLEX
	cv2.putText(frame, fpsInfo, (10, 20), font, 0.4, (255, 255, 255), 1)
	cv2.imshow('@elbruno – DJI Tello Camera', frame)
	sendReadCommand('battery?')
	print(f'battery: {battery} % – i: {i} – {fpsInfo}')
	except Exception as e:
	print(f'exc: {e}')
	pass
	if cv2.waitKey(1) & 0xFF == ord('q'):
	break
	response = sendControlCommand("streamoff")
	print(f'streamon response: {response}')

view raw DjiTelloCameraStreamFaceDetection.py hosted with ❤ by GitHub

In my next posts, I’ll add some drone specific behaviors for each face detected.

References

• DJI Tello Home Page
• DJI Store, Tello
• Amazon, DJI Tello
• DJI Tello SDK

My Posts

• Anaconda, My steps to install a virtual environment with TensorFlow, Keras, OpenCV and more
• Let’s do some Face Recognition with 20 lines in Python
• OpenCV – Show Image – imshow()