Как нормально распознать координаты контуров open-cv на python?

Question

[ZZaRRyaDD]

Есть программа, хотел организовать нормальное распознавание координат, но что-то пошло не так...

import numpy as np
import cv2


#img = cv2.imread("output_3_2_rectangle.png")

img = cv2.imread("output_3_2_rectangle.png")
imgGrey = cv2.cvtColor(img, cv2.COLOR_BGR2GRAY)
_, thrash = cv2.threshold(imgGrey, 240, 255, cv2.THRESH_BINARY)
contours, _ = cv2.findContours(thrash, cv2.RETR_LIST, cv2.CHAIN_APPROX_SIMPLE)

#cv2.imshow("img", img)
#cv2.line(img, (366, 109), (448, 158), (0, 0, 255), 5)
triangle = 0
square = 0
rectangle = 0
pentagon = 0
star = 0
polygon = 0
for contour in contours:
    approx = cv2.approxPolyDP(contour, 0.01 * cv2.arcLength(contour, True), True)

    x = approx.ravel()[0]
    y = approx.ravel()[1] - 5
    n = approx.ravel()
    if len(approx) == 3:
        triangle += 1
        cv2.drawContours(img, [approx], 0, (0, 0, 0), 1)
        cv2.putText(img, "Triangle", (x, y), cv2.FONT_HERSHEY_COMPLEX, 0.5, (0, 0, 0))

        n = approx.ravel()
        font = cv2.FONT_HERSHEY_COMPLEX
        i = 0
        for j in n:
            if(i % 2 == 0):
                x = n[i]
                y = n[i + 1]
                # Строка, содержащая координаты.
                string = str(x) + " " + str(y)
                if(i == 0):
                    # текст верхней координаты.
                    cv2.putText(img, "Arrow tip", (x, y), font, 0.5, (255, 0, 0))
                else:
                    # текст по оставшимся координатам.
                    cv2.putText(img, string, (x, y), font, 0.5, (0, 255, 0))
                i = i + 1
                print(string)
    
    elif len(approx) == 4:
        x1, y1, w, h = cv2.boundingRect(approx)
        aspectRatio = float(w)/h
        print(aspectRatio)
        if aspectRatio >= 0.95 and aspectRatio <= 1.05:
            square += 1
            cv2.drawContours(img, [approx], 0, (0, 0, 0), 1)
            cv2.putText(img, "Square", (x, y), cv2.FONT_HERSHEY_COMPLEX, 0.5, (0, 0, 0))
        else:
        
            rectangle += 1
            cv2.drawContours(img, [approx], 0, (0, 0, 0), 1)
            cv2.putText(img, "Rectangle", (x, y), cv2.FONT_HERSHEY_COMPLEX, 0.5, (0, 0, 0))
        
    elif len(approx) == 5:
        pentagon += 1
        #cv2.drawContours(img, [approx], 0, (0, 0, 0), 5)
        cv2.putText(img, "Pentagon", (x, y),
                cv2.FONT_HERSHEY_COMPLEX, 0.5, (0, 0, 0))
    elif len(approx) == 10:
        star += 1
        #cv2.drawContours(img, [approx], 0, (0, 0, 0), 5)
        cv2.putText(img, "Star", (x, y), cv2.FONT_HERSHEY_COMPLEX, 0.5, (0, 0, 0))
    else:
        polygon += 1
        cv2.drawContours(img, [approx], 0, (0, 0, 0), 5)
        cv2.putText(img, "Polygon", (x, y), cv2.FONT_HERSHEY_COMPLEX, 0.5, (0, 0, 0))


print(triangle)
print(square)
print(rectangle)
print(pentagon)
print(star)
print(polygon)
cv2.imshow("shapes", img)
cv2.imwrite("output_4.jpg", img)
cv2.waitKey(0)
cv2.destroyAllWindows()

Изначальное фото -
Конечное фото -