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fanfuhan OpenCV 教學086 ~ opencv-086-視頻分析(稠密光流分析) – jashliao部落格

2021/12/25

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fanfuhan OpenCV 教學086 ~ opencv-086-視頻分析(稠密光流分析)

資料來源: https://fanfuhan.github.io/

https://fanfuhan.github.io/2019/05/06/opencv-086/

GITHUB:https://github.com/jash-git/fanfuhan_ML_OpenCV

光流跟踪方法分為稠密光流跟踪與稀疏光流跟踪算法，KLT是稀疏光流跟踪算法，前面我們已經介紹過了，OpenCV還支持稠密光流的移動對象跟踪方法，OpenCV中支持的稠密光流算法是由Gunner Farneback在2003年提出來的，它是基於前後兩幀所有像素點的移動估算算法，其效果要比稀疏光流算法更好。

C++

Python

import cv2 as cv
import numpy as np
cap = cv.VideoCapture("D:/images/video/vtest.avi")
ret, frame1 = cap.read()
prvs = cv.cvtColor(frame1,cv.COLOR_BGR2GRAY)
hsv = np.zeros_like(frame1)
hsv[...,1] = 255
while(1):
    ret, frame2 = cap.read()
    next = cv.cvtColor(frame2,cv.COLOR_BGR2GRAY)
    flow = cv.calcOpticalFlowFarneback(prvs,next, None, 0.5, 3, 15, 3, 5, 1.2, 0)
    mag, ang = cv.cartToPolar(flow[...,0], flow[...,1])
    hsv[...,0] = ang*180/np.pi/2
    hsv[...,2] = cv.normalize(mag,None,0,255,cv.NORM_MINMAX)
    bgr = cv.cvtColor(hsv,cv.COLOR_HSV2BGR)
    cv.imshow('frame2',bgr)
    k = cv.waitKey(30) & 0xff
    if k == 27:
        break
    elif k == ord('s'):
        cv.imwrite('opticalfb.png',frame2)
        cv.imwrite('opticalhsv.png',bgr)
    prvs = next
cap.release()
cv.destroyAllWindows()