如何在Python OpenCV图像上找到角（x，y）坐标点？

Question

这是卡车集装箱的俯视图。首先，我需要找到矩形并知道每个角的位置。目标是了解容器的尺寸。

Answer 1

这是一个简单的方法：

1. 获取二值图像。 加载图像，转换为灰度， 高斯模糊，然后大津阈值。

2. 找到扭曲的边界矩形轮廓和角点。我们找到轮廓，然后使用轮廓区域进行过滤以隔离矩形轮廓。接下来我们找到扭曲的边界矩形cv2.minAreaRect()和角cv2.boxPoints()

检测到的边界矩形->遮罩->检测到的角点

角点

(188, 351)
(47, 348)
(194, 32)
(53, 29)

代码

import cv2
import numpy as np

# Load image, grayscale, blur, Otsu's threshold
image = cv2.imread('1.png')
mask = np.zeros(image.shape[:2], dtype=np.uint8)
gray = cv2.cvtColor(image, cv2.COLOR_BGR2GRAY)
blur = cv2.GaussianBlur(gray, (5,5), 0)
thresh = cv2.threshold(blur, 0, 255, cv2.THRESH_BINARY + cv2.THRESH_OTSU)[1]

# Find distorted bounding rect
cnts = cv2.findContours(thresh, cv2.RETR_EXTERNAL, cv2.CHAIN_APPROX_SIMPLE)
cnts = cnts[0] if len(cnts) == 2 else cnts[1]
for c in cnts:
    area = cv2.contourArea(c)
    if area > 5000:
        # Find distorted bounding rect
        rect = cv2.minAreaRect(c)
        corners = cv2.boxPoints(rect)
        corners = np.int0(corners)
        cv2.fillPoly(mask, [corners], (255,255,255))
        
        # Draw corner points
        corners = corners.tolist()
        print(corners)
        for corner in corners:
            x, y = corner
            cv2.circle(image, (x, y), 5, (36,255,12), -1)

cv2.imshow('thresh', thresh)
cv2.imshow('image', image)
cv2.imshow('mask', mask)
cv2.waitKey()