OpenCV的光流的示例代碼錯誤

import numpy as np 
import cv2 

cap = cv2.VideoCapture("slow.avi") 
while not cap.isOpened(): 
    cap = cv2.VideoCapture("slow.avi") 
    cv2.waitKey(1000) 
    print "Wait for the header" 

# 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) 

#print old_frame 

# 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()

我抄光流示例代碼http://docs.opencv.org/trunk/doc/py_tutorials/py_video/py_lucas_kanade/py_lucas_kanade.html但不工作，讓我試圖修復該錯誤消息，但便無法OpenCV的光流的示例代碼錯誤

line 56, in <module> 
cv2.imshow('frame',img) 
error: ..\..\..\opencv-2.4.8.1\modules\highgui\src\window.cpp:269: 
error: (-215) size.width>0 && size.height>0 in function cv::imshow

來源

2014-03-03 Horizon

錯誤消息是相當清楚：您的圖像無法顯示（第56行，），因爲它基本上是空的 - 寬度和高度均爲零。

要驗證這一點，只需print img.shape顯示您的圖像之前。然後你可能會想要調試你的代碼，一步一步地找出結果，並找出結果不是你所期望的。

來源

2014-03-03 11:39:53

難道可以打開AVI文件沒有像它 – Horizon

檢查從cap.read的RETVAL（），您正在忽略。如果它是假的，你不應該在你到達電影結尾或其他出錯時繼續。 –

錯誤的位置：

mask = cv2.line(mask, (a,b),(c,d), color[i].tolist(), 2) 
frame = cv2.circle(frame,(a,b),5,color[i].tolist(),-1)

到：

#drawing is inplace replacement, line() and circle() will return None! 
cv2.line(mask, (a,b),(c,d), color[i].tolist(), 2) 
cv2.circle(frame,(a,b),5,color[i].tolist(),-1)

來源

2014-06-11 21:18:21 user1812003

OpenCV的光流的示例代碼錯誤

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