如何使用Opencv检测三角形交通标志

Question

我写了一个代码片段来检测交通标志的形状。该代码对于检测除三角形交通标志以外的形状相当有效。我尝试将值(即 0.01(调整为函数 cv2.approxPolyDP(c， 0.01 * peri， True( 的第二个参数，但我无法找到正确的值。

我尝试将值(即 0.01(调整为函数 cv2.approxPolyDP(c， 0.01 * peri， True( 的第二个参数，但我无法找到正确的值。

 from os import listdir
from os.path import isfile, join
import cv2
myPath = '/home/raghu/Downloads/SSIMProject/ImageData/sample'
files = [ f for f in listdir(myPath) if isfile(join(myPath, f))]
for eachFile in files:
    img = cv2.imread(join(myPath, eachFile), 1)
    cv2.imshow('img1', img[:,:,0])
    ret, thresh1 = cv2.threshold(img[:,:,0], 0, 255, cv2.THRESH_BINARY_INV + cv2.THRESH_OTSU)
    contours,hierarchy = cv2.findContours(thresh1, cv2.RETR_EXTERNAL, cv2.CHAIN_APPROX_NONE)
    font = cv2.FONT_HERSHEY_COMPLEX
    for cnt in contours:
        approx = cv2.approxPolyDP(cnt, 0.0112 * cv2.arcLength(cnt, True), True)
        print(len(approx))
        if len(approx) == 8:
            print("Octagon")
            cv2.putText(img, 'Octagon', (10, 30), font, 0.3, (0, 0, 0), 1, cv2.LINE_AA)
            cv2.drawContours(img, [cnt], 0, (0, 255, 0), 2)
        elif len(approx) == 7:
            print("Heptagon")
            cv2.putText(img, 'Heptagon', (10, 30), font, 0.3, (0, 0, 0), 1, cv2.LINE_AA)
            cv2.drawContours(img, [cnt], 0, (0, 255, 0), 2)
        elif len(approx) == 6:
            print("Hexagon")
            cv2.putText(img, 'Hexagon', (10, 30), font, 0.3, (0, 0, 0), 1, cv2.LINE_AA)
            cv2.drawContours(img, [cnt], 0, (0, 255, 0), 2)
        elif len(approx) == 5:
            print("Pentagon")
            cv2.putText(img, 'Pentagon', (10, 30), font, 0.3, (0, 0, 0), 1, cv2.LINE_AA)
            cv2.drawContours(img, [cnt], 0, (0, 255, 0), 2)
        elif len(approx) == 4:
            print("Square")
            cv2.putText(img, 'Square', (10, 30), font, 0.3, (0, 0, 0), 1, cv2.LINE_AA)
            cv2.drawContours(img, [cnt], 0, (0, 255, 0), 2)
        elif len(approx) == 3:
            print("Triangle")
            cv2.putText(img, 'Triangle', (10, 30), font, 0.3, (0, 0, 0), 1, cv2.LINE_AA)
            cv2.drawContours(img, [cnt], 0, (0, 255, 0), 2)
        else:
            print("Circle")
            cv2.putText(img, 'Circle', (10, 30), font, 0.3, (0, 0, 0), 1, cv2.LINE_AA)
            cv2.drawContours(img, [cnt], 0, (0, 255, 0), 2)
    cv2.imshow('sign', img)
    cv2.waitKey(0)
    cv2.destroyAllWindows()

我希望三角形的交通标志被检测到。

Answer 1

请尝试以下代码，它将帮助您检测图像中的三角形一旦您可以根据交通三角形(例如红色过滤器(的颜色创建一个颜色过滤器，然后使用它，以便它始终仅检测红色标志

import cv2
import numpy as np
font = cv2.FONT_HERSHEY_COMPLEX
img = cv2.imread("shapes.jpg", cv2.IMREAD_GRAYSCALE)
_, threshold = cv2.threshold(img, 240, 255, cv2.THRESH_BINARY)
_, contours, _ = cv2.findContours(threshold, cv2.RETR_TREE, cv2.CHAIN_APPROX_SIMPLE)
for cnt in contours:
    approx = cv2.approxPolyDP(cnt, 0.01*cv2.arcLength(cnt, True), True)
    cv2.drawContours(img, [approx], 0, (0), 5)
    x = approx.ravel()[0]
    y = approx.ravel()[1]
cv2.putText(img, "Triangle", (x, y), font, 1, (0))
cv2.imshow("shapes", img)
cv2.imshow("Threshold", threshold)
cv2.waitKey(0)
cv2.destroyAllWindows()