如何使用 opencv 在视频上绘制尾随线

Question

Im trying to draw a path using dots on the video during certain timestamp interval. The code is working fine but the previous position of the dot dissapears, I dont want it to dissapear. Can anyone help me as to what to tweak in this code to preseve all the dots.

from collections import deque
from imutils.video import VideoStream
import numpy as np
import cv2
import imutils
import time
from numpy import random

vs = cv2.VideoCapture('/media/intercept.mp4')
pts = deque(maxlen=64) #buffer size

#Position to start drawing the dots
i=0
j=330
# keep looping
while True:
    ret,frame = vs.read()

    if frame is None:
        break
    # resize the frame, blur it, and convert it to the HSV color space
    frame = imutils.resize(frame, width=1800)
    blurred = cv2.GaussianBlur(frame, (11, 11), 0)
    hsv = cv2.cvtColor(frame, cv2.COLOR_BGR2HSV)

    i+=2
    j=j-random.randint(-10,10) #introduce some jitter/randomness
    i=i+random.randint(-10,10)

    timestamps = vs.get(cv2.CAP_PROP_POS_MSEC)
    if (15000<timestamps<20000):
        print (i,j, "DRAWING")
        cv2.circle(frame,(i, j),10, (0,0,255), -1) #draw dot


    cv2.imshow("Frame", frame)
    key = cv2.waitKey(1) & 0xFF
    # if the 'q' key is pressed, stop the loop
    if key == ord("q"):
        break

cv2.destroyAllWindows()
vs.release()    

Answer 1

Was able to fix this one

from collections import deque
from imutils.video import VideoStream
import numpy as np
import cv2
import imutils
import time
from numpy import random

vs = cv2.VideoCapture('/media/intercept.mp4')
pts = deque(maxlen=64) #buffer size
color = np.random.randint(0,255,(100,3))
ret, old_frame = vs.read() 
old_frame = imutils.resize(old_frame,width=1800)
mask = np.zeros_like(old_frame)

i=0
j=330
ct=0
# keep looping
while True:
    ret,frame = vs.read()

    if frame is None:
        break
    # resize the frame, blur it, and convert it to the HSV color space
    frame = imutils.resize(frame, width=1800)
    blurred = cv2.GaussianBlur(frame, (11, 11), 0)
    hsv = cv2.cvtColor(frame, cv2.COLOR_BGR2HSV)
    x=i
    y=j
    i+=2
    j=j-random.randint(-10,10)
    i=i+random.randint(-10,10)
    print (int(i%330))
    ct+=10

    timestamps = vs.get(cv2.CAP_PROP_POS_MSEC)
    if (1000<timestamps<20000):
        print (i,j, "Drawing")
        #cv2.circle(frame,(i, j),10, (0,0,255), -1) #draw circle
        mask = cv2.line(mask, (x,y),(i,j),[255,0,9], 2)
        frame = cv2.circle(frame,(i,j),5,[0,255,222],-1)

    img = cv2.add(frame,mask)
    cv2.imshow("Frame", img)
    key = cv2.waitKey(1) & 0xFF
    # if the 'q' key is pressed, stop the loop
    if key == ord("q"):
        break

cv2.destroyAllWindows()
vs.release()