Line Follower using computer, remove false positives

Follower_CV_4.py

from picamera.array import PiRGBArray
from picamera import PiCamera
import time
import cv2
import numpy as np
import RPi.GPIO as GPIO

GPIO.setmode(GPIO.BOARD)
GPIO.setup(40, GPIO.OUT)
GPIO.output(40, GPIO.HIGH)

camera = PiCamera()
camera.resolution = (640, 360)
camera.rotation = 180
rawCapture = PiRGBArray(camera, size=(640, 360))
time.sleep(0.1)

x_last = 320
y_last = 180


for frame in camera.capture_continuous(rawCapture, format="bgr", use_video_port=True):	
	image = frame.array	
	Blackline = cv2.inRange(image, (0,0,0), (75,75,75))	
	kernel = np.ones((3,3), np.uint8)
	Blackline = cv2.erode(Blackline, kernel, iterations=5)
	Blackline = cv2.dilate(Blackline, kernel, iterations=9)	
	img_blk,contours_blk, hierarchy_blk = cv2.findContours(Blackline.copy(),cv2.RETR_TREE,cv2.CHAIN_APPROX_SIMPLE)
	
	contours_blk_len = len(contours_blk)
	if contours_blk_len > 0 :
	 if contours_blk_len == 1 :
	  blackbox = cv2.minAreaRect(contours_blk[0])
	 else:
	   canditates=[]
	   off_bottom = 0	   
	   for con_num in range(contours_blk_len):		
		blackbox = cv2.minAreaRect(contours_blk[con_num])
		(x_min, y_min), (w_min, h_min), ang = blackbox		
		box = cv2.boxPoints(blackbox)
		(x_box,y_box) = box[0]
		if y_box > 358 :		 
		 off_bottom += 1
		canditates.append((y_box,con_num,x_min,y_min))		
	   canditates = sorted(canditates)
	   if off_bottom > 1:	    
		canditates_off_bottom=[]
		for con_num in range ((contours_blk_len - off_bottom), contours_blk_len):
		   (y_highest,con_highest,x_min, y_min) = canditates[con_num]		
		   total_distance = (abs(x_min - x_last)**2 + abs(y_min - y_last)**2)**0.5
		   canditates_off_bottom.append((total_distance,con_highest))
		canditates_off_bottom = sorted(canditates_off_bottom)         
		(total_distance,con_highest) = canditates_off_bottom[0]         
		blackbox = cv2.minAreaRect(contours_blk[con_highest])	   
	   else:		
		(y_highest,con_highest,x_min, y_min) = canditates[contours_blk_len-1]		
		blackbox = cv2.minAreaRect(contours_blk[con_highest])	 
	 (x_min, y_min), (w_min, h_min), ang = blackbox
	 x_last = x_min
	 y_last = y_min
	 if ang < -45 :
	  ang = 90 + ang
	 if w_min < h_min and ang > 0:	  
	  ang = (90-ang)*-1
	 if w_min > h_min and ang < 0:
	  ang = 90 + ang	  
	 setpoint = 320
	 error = int(x_min - setpoint) 
	 ang = int(ang)	 
	 box = cv2.boxPoints(blackbox)
	 box = np.int0(box)
	 cv2.drawContours(image,[box],0,(0,0,255),3)	 
	 cv2.putText(image,str(ang),(10, 40), cv2.FONT_HERSHEY_SIMPLEX, 1, (0, 0, 255), 2)
	 cv2.putText(image,str(error),(10, 320), cv2.FONT_HERSHEY_SIMPLEX, 1, (255, 0, 0), 2)
	 cv2.line(image, (int(x_min),200 ), (int(x_min),250 ), (255,0,0),3)
	 
	  	
	cv2.imshow("orginal with line", image)	
	rawCapture.truncate(0)	
	key = cv2.waitKey(1) & 0xFF	
	if key == ord("q"):
		break

GPIO.output(40, GPIO.LOW)

WHEN I RUN THIS CODE TO CHECK HERE COMES
/usr/lib/python2.7/dist-packages/picamera/encoders.py:544: PiCameraResolutionRounded: frame size rounded up from 640x360 to 640x368
width, height, fwidth, fheight)))
Traceback (most recent call last):
File "follower.py", line 29, in
img_blk,contours_blk, hierarchy_blk = cv2.findContours(Blackline.copy(),cv2.RETR_TREE,cv2.CHAIN_APPROX_SIMPLE)
ValueError: need more than 2 values to unpack

WHAT TO DO FOR THIS?

remove img_blk if using cv2 or 4

Traceback (most recent call last):
(Y_highest, con_highest,x_min,y_min)=candidates[contours_len -1]
IndexError: list index out of range
What to do?

_, contours_blk, _ = cv2.findContours(Blackline.copy(),cv2.RETR_TREE,cv2.CHAIN_APPROX_SIMPLE)

Doing this will eliminate the error.

where you defined x_last and y_last
I can't find, can you help me

Hello,

I have an error claiming that contours_blk is out of range.
Error below:
Traceback (most recent call last):
File "Follower_CV_42.py", line 58, in
(y_highest,con_highest,x_min, y_min) = canditates[contours_blk_len-1]
IndexError: list index out of range

Can you please give me a hint for this?

Thanks in advance

Hello,

I have an error claiming that contours_blk is out of range. Error below: Traceback (most recent call last): File "Follower_CV_42.py", line 58, in (y_highest,con_highest,x_min, y_min) = canditates[contours_blk_len-1] IndexError: list index out of range

Can you please give me a hint for this?

Thanks in advance

Please provide the response to this issue