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python - TypeError: 'NoneType' object is not iterable , python opencv

问题描述

I am getting an error showing: line 34, in drow_the_lines for line in lines: TypeError: 'NoneType' object is not iterable

I am not getting the reason for this error, kindly do suggest what could be the reason for this error

Here is my complete code:

import cv2
import numpy as np
def region_of_interest(img, vertices):
    mask = np.zeros_like(img)
    match_mask_color = 255
    cv2.fillPoly(mask, vertices, match_mask_color)
    masked_image = cv2.bitwise_and(img, mask)
    return masked_image

def drow_the_lines(img, lines):
    img = np.copy(img)
    blank_image = np.zeros((img.shape[0], img.shape[1], 3), dtype=np.uint8)
    #Drawing the lines
    for line in lines:
        for x1, y1, x2, y2 in line:
            cv2.line(blank_image, (x1, y1), (x2, y2), (0, 255, 0), thickness=3)
    img = cv2.addWeighted(img, 0.8, blank_image, 1, 0.0)
    return img

def process(image):
    print(image.shape)
    height = image.shape[0]
    width = image.shape[1]
    region_of_interest_vertices = [
        (0, height),
        (width/2, height/2),
        (width, height)
    ]

    #finding out the edges
    gray_image = cv2.cvtColor(image, cv2.COLOR_BGR2GRAY)
    canny_image = cv2.Canny(gray_image, 100, 200)
    cropped_image = region_of_interest(canny_image, np.array([region_of_interest_vertices], np.int32),)
    lines = cv2.HoughLinesP(cropped_image,
                            rho=6,
                            theta=np.pi/60,
                            threshold=160,
                            lines=np.array([]),
                            minLineLength=40,
                            maxLineGap=25)
    image_with_lines = drow_the_lines(image, lines)
    return image_with_lines

cap = cv2.VideoCapture('roadVideo.mp4')

while(cap.isOpened()):
    ret, frame = cap.read()
    frame = process(frame)
    cv2.imshow('frame', frame)
    if cv2.waitKey(1) & 0xFF == ord('q'):
        break

cap.release()
cv2.destroyAllWindows()

标签： pythonopencv

解决方案

无法直接回答您的问题，但无类型错误意味着它看不到任何东西，例如它跌倒的线没有什么可看的。因此，如果我的计数正确，第 34 行是：

lines = cv2.HoughLinesP(cropped_image,
                            rho=6,
                            theta=np.pi/60,
                            threshold=160,
                            lines=np.array([]),
                            minLineLength=40,
                            maxLineGap=25)

这可能意味着cropped_image 是空的？

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