如何使用opencv python检测视频中选定方形区域中的orb特征

Question

上午做一个关于选定对象跟踪的项目作为其中的一部分我必须使用opencv和python检测所选方形区域中的orb功能视频。但是这段代码不起作用。请帮助我并提前感谢

import numpy as np  
import cv2  
rect = (0,0,0,0)  
startPoint = False  
endPoint = False  

def on_mouse(event,x,y,flags,params):  

    global rect,startPoint,endPoint  

    # get mouse click  
    if event == cv2.EVENT_LBUTTONDOWN:  

        if startPoint == True and endPoint == True:  
            startPoint = False  
            endPoint = False  
            rect = (0, 0, 0, 0)  

        if startPoint == False:  
            rect = (x, y, 0, 0)  
            startPoint = True  
        elif endPoint == False:  
            rect = (rect[0], rect[1], x, y)  
            endPoint = True  

cap = cv2.VideoCapture('demo.mp4')  
waitTime = 50  

#Reading the first frame  
(grabbed, frame) = cap.read()  
#taking frames one by one  
while(cap.isOpened()):  

    (grabbed, frame) = cap.read()  

    cv2.namedWindow('frame')  
    cv2.setMouseCallback('frame', on_mouse)      
    gray = cv2.cvtColor(frame,cv2.COLOR_BGR2GRAY)  
    orb = cv2.ORB_create()  
    kp = orb.detect(gray,None)  
    img2=frame.copy()  
    frame=cv2.drawKeypoints(gray,kp,img2,color=(0,255,0),flags=0)  
    cv2.imshow('frame', img2)  
#waitkey  
    if cv2.waitKey(10)==27:  
        break  
        cv2.imshow('Video', img2)  
cap.release()  
cv2.destroyAllWindows()