视频光流

import numpy as np
import cv2
lk_params=dict( winSize=(15,15),
                  maxLevel=3,
                  criteria=(cv2.TERM_CRITERIA_EPS|cv2.TERM_CRITERIA_COUNT,10,0.03))
feature_params=dict( maxCorners=800,
                       qualityLevel=0.3,
                       minDistance=7,
                       blockSize=7 )
class App:
    def __init__(self,video_src):
        self.track_len=10#跟踪轨迹长度
        self.detect_interval=5
        self.tracks=[]#储存跟踪点
        self.cam=cv2.VideoCapture('C:/Users/xpp/Desktop/2021091.avi')
        self.frame_idx=0
    def run(self):
        while True:
            ret,frame=self.cam.read()
            frame_gray=cv2.cvtColor(frame,cv2.COLOR_BGR2GRAY)
            vis=frame.copy()
            if len(self.tracks)>0:
                img0,img1=self.prev_gray,frame_gray
                p0=np.float32([tr[-1] for tr in self.tracks]).reshape(-1,1,2)
                p1,st,err=cv2.calcOpticalFlowPyrLK(img0,img1,p0,None,**lk_params)
                p0r,st, err=cv2.calcOpticalFlowPyrLK(img1,img0,p1,None,**lk_params)
                d=abs(p0-p0r).reshape(-1,2).max(-1)
                good=d<1
                new_tracks=[]
                for tr,(x,y),good_flag in zip(self.tracks,p1.reshape(-1,2),good):
                    if not good_flag:
                        continue
                    tr.append((x,y))
                    if len(tr)>self.track_len:
                        del tr[0]
                    new_tracks.append(tr)
                    cv2.circle(vis,(x,y),2,(0,255,0),-1)
                self.tracks=new_tracks
                cv2.polylines(vis,[np.int32(tr) for tr in self.tracks],False,(0,255,0))
            if self.frame_idx%self.detect_interval==0:
                mask=np.zeros_like(frame_gray)
                mask[:]=255
                for x,y in [np.int32(tr[-1]) for tr in self.tracks]:
                    cv2.circle(mask,(x,y),5,0,-1)
                p=cv2.goodFeaturesToTrack(frame_gray,mask=mask,**feature_params)
                if p is not None:
                    for x, y in np.float32(p).reshape(-1,2):
                        self.tracks.append([(x,y)])
            self.frame_idx+=1
            self.prev_gray=frame_gray
            cv2.imshow('lk_track',vis)
            ch=cv2.waitKey(1)
            if ch==27:
                break
def main():
    video_src='video.flv'
    App(video_src).run()
    cv2.destroyAllWindows()
if __name__=='__main__':
    main()