I'm working on a image analysis project. encountering this error and not sure hot to solve it , cuz the function 'detect_balls' returns three values but couldn't assign it to variables whre it is called out to . Would really appriciate your help . the code is attached below
import numpy as np
import cv2
import sys
import time
bgr_color = 29,2,128 #129,119,195
color_threshold = 50 #color range
hsv_color = cv2.cvtColor( np.uint8([[bgr_color]] ), cv2.COLOR_BGR2HSV)[0][0]
HSV_lower = np.array([hsv_color[0] - color_threshold, hsv_color[1] - color_threshold, hsv_color[2] - color_threshold])
HSV_upper = np.array([hsv_color[0] + color_threshold, hsv_color[1] + color_threshold, hsv_color[2] + color_threshold])
def detect_ball(frame):
x, y, radius = -1, -1, -1
hsv_frame = cv2.cvtColor(frame, cv2.COLOR_BGR2HSV)
mask = cv2.inRange(hsv_frame, HSV_lower, HSV_upper)
mask = cv2.erode(mask, None, iterations=1)
mask = cv2.dilate(mask, None, iterations=1)
im2, contours, hierarchy = cv2.findContours(mask.copy(), cv2.RETR_EXTERNAL, cv2.CHAIN_APPROX_SIMPLE)
center = (-1, -1)
if len(contours) > 0:
c = max(contours, key=cv2.contourArea)
((x, y), radius) = cv2.minEnclosingCircle(c)
M = cv2.moments(mask)
center = (int(M["m10"] / M["m00"]), int(M["m01"] / M["m00"])) #position of the ball
if radius > 10:
#outline ball
cv2.circle(frame, (int(x), int(y)), int(radius), (255, 0, 0), 2)
#show ball center
cv2.circle(frame, center, 5, (0, 255, 0), -1)
return center[0], center[1], radius
if __name__ == "__main__":
filepath = '/home/venkat-com/Desktop/track/golf01_preview.mp4'
cap = cv2.VideoCapture(filepath)
dist = []
times = []
count = 0
kalmanFilter = []
variance = []
initialEstimatedVariance = 1
deltaX = cap.get(cv2.CAP_PROP_FRAME_WIDTH)
deltat = 524
noise = 1
sensorCovariance = 83791.65209996712
variance.append(initialEstimatedVariance)
while(cap.isOpened()):
count+=1
ret, frame = cap.read()
#detect_ball(frame)
[x,y,r] = detect_ball(frame)
if (len(dist) != 0):
x_prev = dist[len(dist) - 1]
velocity = float(deltaX)/deltat
dist.append(x)
estimatedX = x_prev + velocity
estimatedVariance = variance[len(variance)-1] + noise
kalmanGain = float(estimatedVariance)/(estimatedVariance + sensorCovariance)
kalmanPosition = estimatedX + (kalmanGain*(x - estimatedX))
kalmanFilter.append(kalmanPosition)
updatedVariance = estimatedVariance-(kalmanGain*estimatedVariance)
variance.append(updatedVariance)
print (kalmanFilter)
#print(variance)
else: #don't do any calculations on the 1st point
x_initial = detect_ball(frame)[0]
dist.append(x_initial)
kalmanFilter.append(x_initial)
# Display the resulting frame
cv2.namedWindow('frame', cv2.WINDOW_NORMAL) # Create window with freedom of dimensions
imS = cv2.resizeWindow('frame', (960, 540)) # Resize image
cv2.imshow('frame', frame)
if cv2.waitKey(1) & 0xFF == ord('q'):
break
# When everything done, release the capture
cap.release()
cv2.destroyAllWindows()
Tried to check the values given out by the function, and all of them were correct and no null values
This is the terminal's output trying to run the code :
Traceback (most recent call last):
File "/home/venkat-com/trajectory.py", line 67, in <module>
[x,y,r] = detect_ball(frame)
File "/home/venkat-com/trajectory.py", line 22, in detect_ball
im2, contours, hierarchy = cv2.findContours(mask.copy(), cv2.RETR_EXTERNAL, cv2.CHAIN_APPROX_SIMPLE)
ValueError: not enough values to unpack (expected 3, got 2)
