如何在可能会有些变形的网格中订购cv2轮廓？

您可以基于原点的拐角距离和相对拐角位置来选择排序。

• Find contours and hierarchy.

保持轮廓无子（基于层次结构）。

• Find corners of bounding rectangles.

根据以下条件分析拐角（或更简单的条件）：

• Top left contours is the one with the minimum distance of top left corner.
• Bottom right contours is the one with the maximum distance of top left corner.
• Other two contours can be separated by maximum x and maximum y (after eliminating the top left and bottom right).

以下解决方案以颜色绘制边界矩形以进行测试：

1. Red
2. Green
3. Blue
4. Yellow

这是一个工作代码示例（请阅读注释）：

import numpy as np
import cv2

# Read input image as Grayscale
img = cv2.imread('img.png', cv2.IMREAD_GRAYSCALE)

# Convert img to uint8 binary image with values 0 and 255
# All black pixels goes to 0, and other pixels goes to 255
ret, thresh_gray = cv2.threshold(img, 1, 255, cv2.THRESH_BINARY)

# Find contours in thresh_gray.
cnts, hiers = cv2.findContours(thresh_gray, cv2.RETR_TREE, cv2.CHAIN_APPROX_NONE)[-2:]  # [-2:] indexing takes return value before last (due to OpenCV compatibility issues).

corners = [] # List of corners
dist = np.array([]) # Array of distance from axes origin

# Iterate cnts and hiers, find bounding rectangles, and add corners to a list
for c, h in zip(cnts, hiers[0]):
    # If contours has no child
    if h[2] == -1:
        # Get bounding rectangle
        x, y, w, h = cv2.boundingRect(c)

        # Append corner to list of corners - format is corners[i] holds a tuple: ((x0, y0), (x1, y1))
        p0 = (x, y)
        p1 = (x+w, y+h)
        corners.append((p0, p1))

        # Distance of corners from origin
        d = np.array([np.linalg.norm(p0), np.linalg.norm(p1)])

        if dist.size == 0:
            dist = d
        else:
            dist = np.vstack((dist, d))


top_left = np.argmin(dist[:,0]) # Index of top left corner (assume minimum distance from origin)
bottom_right = np.argmax(dist[:,1]) # Index of top bottom right corner (assume maximum distance from origin)

tmp_corners = np.array(corners)
tmp_corners[top_left, :, :] = np.array(((0,0), (0,0))) #Ignore top_left corners
tmp_corners[bottom_right, :, :] = np.array(((0,0), (0,0))) #Ignore bottom_right corners
bottom_left = np.argmax(tmp_corners[:,1,1]) #Maximum y is bottom left
tmp_corners[bottom_left, :, :] = np.array(((0,0), (0,0))) #Ignore bottom_left corners
top_right = np.argmax(tmp_corners[:,1,0])  #Maximum x is top right

# Convert Grayscale to BGR (just for testing - for drawing rectangles in green color).
out = cv2.cvtColor(img, cv2.COLOR_GRAY2BGR)

# Draw rectangles (for testing)
# 1. Red
# 2. Green
# 3. Blue
# 4. Yellow
cv2.rectangle(out, corners[top_left][0], corners[top_left][1], (0, 0, 255), thickness = 2)
cv2.rectangle(out, corners[bottom_left][0], corners[bottom_left][1], (0, 255, 0), thickness = 2)
cv2.rectangle(out, corners[top_right][0], corners[top_right][1], (255, 0, 0), thickness = 2)
cv2.rectangle(out, corners[bottom_right][0], corners[bottom_right][1], (0, 255, 255), thickness = 2)

cv2.imwrite('out.png', out)  #Save out to file (for testing).


# Show result (for testing).
cv2.imshow('thresh_gray', thresh_gray)
cv2.imshow('out', out)
cv2.waitKey(0)
cv2.destroyAllWindows()

结果：

回答来源：stackoverflow