Question

我试图从OpenCV网站运行python示例：

http://docs.opencv.org/trunk/d7/d8b/tutorial_py_lucas_kanade.html

import numpy as np
import cv2
cap = cv2.VideoCapture('slow.flv')
# params for ShiTomasi corner detection
feature_params = dict( maxCorners = 100,
                       qualityLevel = 0.3,
                       minDistance = 7,
                       blockSize = 7 )
# Parameters for lucas kanade optical flow
lk_params = dict( winSize  = (15,15),
                  maxLevel = 2,
                  criteria = (cv2.TERM_CRITERIA_EPS | cv2.TERM_CRITERIA_COUNT, 10, 0.03))
# Create some random colors
color = np.random.randint(0,255,(100,3))
# Take first frame and find corners in it
ret, old_frame = cap.read()
old_gray = cv2.cvtColor(old_frame, cv2.COLOR_BGR2GRAY)
p0 = cv2.goodFeaturesToTrack(old_gray, mask = None, **feature_params)
# Create a mask image for drawing purposes
mask = np.zeros_like(old_frame)
while(1):
    ret,frame = cap.read()
    frame_gray = cv2.cvtColor(frame, cv2.COLOR_BGR2GRAY)
    # calculate optical flow
    p1, st, err = cv2.calcOpticalFlowPyrLK(old_gray, frame_gray, p0, None, **lk_params)
    # Select good points
    good_new = p1[st==1]
    good_old = p0[st==1]
    # draw the tracks
    for i,(new,old) in enumerate(zip(good_new,good_old)):
        a,b = new.ravel()
        c,d = old.ravel()
        mask = cv2.line(mask, (a,b),(c,d), color[i].tolist(), 2)
        frame = cv2.circle(frame,(a,b),5,color[i].tolist(),-1)
    img = cv2.add(frame,mask)
    cv2.imshow('frame',img)
    k = cv2.waitKey(30) & 0xff
    if k == 27:
        break
    # Now update the previous frame and previous points
    old_gray = frame_gray.copy()
    p0 = good_new.reshape(-1,1,2)
cv2.destroyAllWindows()
cap.release()

我使用Python 3来运行此示例

它可以工作但我的视频只有5-15秒，然后在下一个错误时停止：

回溯（最近一次呼叫最后一次）：文件＆＃34; o.py＆＃34;，第28行，in good_new = p1 [st == 1] TypeError：＆＃39; NoneType＆＃39;对象不可订阅

这个例子有什么不妥？

Answer 1

如果所有光学流动对象（屏幕上的颜色点）都离开框架，则会发生这种情况。这样做 - 如果数组p1为空，再次找到特征然后计算光流。这应该有用。

在while循环中添加它（但它只是随着时间的推移用线填充整个屏幕）：

if p1 is None:
   p0 = cv2.goodFeaturesToTrack(old_gray, mask = None, **feature_params)
   p1, st, err = cv2.calcOpticalFlowPyrLK(...., **lk_params)

OpenCV示例错误 - TypeError：＆＃39; NoneType＆＃39;对象不可订阅

1 个答案: