实棋盘在线下棋项目board_calibration.py中augmented_corners未定义问题求助

错误信息 #

Traceback (most recent call last):
  File "board_calibration.py", line 200, in <module>
NameError: name 'augmented_corners' is not defined
[12216] Failed to execute script 'board_calibration' due to unhandled exception!

问题原因 #

augmented_corners、rotation_count、roi_mask这些变量仅在棋盘成功被检测到的分支（即if retval:代码块内部）才会被定义。如果用户在棋盘未被检测到时按下q退出主循环，后续代码尝试访问这些未定义的变量，就会触发NameError。

修复方案 #

核心思路 #

提前初始化变量并增加检测判断，确保无论是否完成棋盘检测，代码都能安全执行：

1. 提前初始化变量：在进入主循环前，为所有后续依赖的变量设置默认值，避免未定义状态。
2. 增加退出判断：在执行后续依赖变量的代码前，检查是否完成棋盘检测，未完成则直接终止程序。

完整修复后的代码 #

import cv2
import platform
from math import inf, sqrt
import pickle
from helper import rotateMatrix, perspective_transform, edge_detection
import numpy as np
import sys
from tkinter import messagebox
import tkinter as tk

show_info = False
cap_index = 0
cap_api = cv2.CAP_ANY
platform_name = platform.system()
for argument in sys.argv:
    if argument == "show-info":
        show_info = True
    elif argument.startswith("cap="):
        cap_index = int("".join(c for c in argument if c.isdigit()))
        if platform_name == "Darwin":
            cap_api = cv2.CAP_AVFOUNDATION
        elif platform_name == "Linux":
            cap_api = cv2.CAP_V4L2
        else:
            cap_api = cv2.CAP_DSHOW

if show_info:
    root = tk.Tk()
    root.withdraw()
    messagebox.showinfo("Board Calibration",
                        'Board calibration will start. It should detect corners of the chess board almost immediately. If it does not, you should press key "q" to stop board calibration and change webcam/board position.')
    if platform_name == "Darwin":
        root.destroy()


def mark_corners(frame, augmented_corners, rotation_count):
    height, width = frame.shape[:2]
    if rotation_count == 1:
        frame = cv2.rotate(frame, cv2.ROTATE_90_CLOCKWISE)
    elif rotation_count == 2:
        frame = cv2.rotate(frame, cv2.ROTATE_180)
    elif rotation_count == 3:
        frame = cv2.rotate(frame, cv2.ROTATE_90_COUNTERCLOCKWISE)

    for i in range(len(augmented_corners)):
        for j in range(len(augmented_corners[i])):
            if rotation_count == 0:
                index = str(i) + "," + str(j)
                corner = augmented_corners[i][j]
            elif rotation_count == 1:
                index = str(j) + "," + str(8 - i)
                corner = (height - augmented_corners[i][j][1], augmented_corners[i][j][0])
            elif rotation_count == 2:
                index = str(8 - i) + "," + str(8 - j)
                corner = (width - augmented_corners[i][j][0], height - augmented_corners[i][j][1])
            elif rotation_count == 3:
                index = str(8 - j) + "," + str(i)
                corner = (augmented_corners[i][j][1], width - augmented_corners[i][j][0])
            corner = (int(corner[0]), int(corner[1]))
            frame = cv2.putText(frame, index, corner, cv2.FONT_HERSHEY_SIMPLEX,
                                0.5, (255, 0, 0), 1, cv2.LINE_AA)

    return frame


cap = cv2.VideoCapture(cap_index, cap_api)
if not cap.isOpened():
    print("Couldn't open your webcam. Please check your webcam connection.")
    sys.exit(0)
board_dimensions = (7, 7)

# 提前初始化变量，避免未定义报错
augmented_corners = None
rotation_count = 0
roi_mask = None

for _ in range(10):
    ret, frame = cap.read()
    if ret == False:
        print("Error reading frame. Please check your webcam connection.")
        continue

while True:
    ret, frame = cap.read()
    if ret == False:
        print("Error reading frame. Please check your webcam connection.")
        continue
    gray = cv2.cvtColor(frame, cv2.COLOR_BGR2GRAY)
    retval, corners = cv2.findChessboardCorners(gray, patternSize=board_dimensions)
    if retval:
        if show_info:
            if platform_name == "Darwin":
                root = tk.Tk()
                root.withdraw()
            messagebox.showinfo("Chess Board Detected",
                                'Please check that corners of your chess board are correctly detected. The square covered by points (0,0), (0,1),(1,0) and (1,1) should be a8. You can rotate the image by pressing key "r" to adjust that. Press key "q" to save detected chess board corners and finish board calibration.')
            root.destroy()
        if corners[0][0][0] > corners[-1][0][0]:  # corners returned in reverse order
            corners = corners[::-1]
        minX, maxX, minY, maxY = inf, -inf, inf, -inf
        augmented_corners = []
        row = []
        for i in range(6):
            corner1 = corners[i]
            corner2 = corners[i + 8]
            x = corner1[0][0] + (corner1[0][0] - corner2[0][0])
            y = corner1[0][1] + (corner1[0][1] - corner2[0][1])
            row.append((x, y))

        for i in range(4, 7):
            corner1 = corners[i]
            corner2 = corners[i + 6]
            x = corner1[0][0] + (corner1[0][0] - corner2[0][0])
            y = corner1[0][1] + (corner1[0][1] - corner2[0][1])
            row.append((x, y))

        augmented_corners.append(row)

        for i in range(7):
            row = []
            corner1 = corners[i * 7]
            corner2 = corners[i * 7 + 1]
            x = corner1[0][0] + (corner1[0][0] - corner2[0][0])
            y = corner1[0][1] + (corner1[0][1] - corner2[0][1])
            row.append((x, y))

            for corner in corners[i * 7:(i + 1) * 7]:
                x = corner[0][0]
                y = corner[0][1]
                row.append((x, y))

            corner1 = corners[i * 7 + 6]
            corner2 = corners[i * 7 + 5]
            x = corner1[0][0] + (corner1[0][0] - corner2[0][0])
            y = corner1[0][1] + (corner1[0][1] - corner2[0][1])
            row.append((x, y))
            augmented_corners.append(row)

        row = []
        for i in range(6):
            corner1 = corners[42 + i]
            corner2 = corners[42 + i - 6]
            x = corner1[0][0] + (corner1[0][0] - corner2[0][0])
            y = corner1[0][1] + (corner1[0][1] - corner2[0][1])
            row.append((x, y))

        for i in range(4, 7):
            corner1 = corners[42 + i]
            corner2 = corners[42 + i - 8]
            x = corner1[0][0] + (corner1[0][0] - corner2[0][0])
            y = corner1[0][1] + (corner1[0][1] - corner2[0][1])
            row.append((x, y))

        augmented_corners.append(row)

        while augmented_corners[0][0][0] > augmented_corners[8][8][0] or augmented_corners[0][0][1] > \
                augmented_corners[8][8][1]:
            rotateMatrix(augmented_corners)

        pts1 = np.float32([list(augmented_corners[0][0]), list(augmented_corners[8][0]), list(augmented_corners[0][8]),
                           list(augmented_corners[8][8])])

        empty_board = perspective_transform(frame, pts1)
        edges = edge_detection(empty_board)
        kernel = np.ones((7, 7), np.uint8)
        edges = cv2.dilate(edges, kernel, iterations=1)
        roi_mask = cv2.bitwise_not(edges)
        roi_mask[:7, :] = 0
        roi_mask[:, :7] = 0
        roi_mask[-7:, :] = 0
        roi_mask[:, -7:] = 0

        rotation_count = 0
        while True:
            cv2.imshow('frame', mark_corners(frame.copy(), augmented_corners, rotation_count))
            response = cv2.waitKey(0)
            if response & 0xFF == ord('r'):
                rotation_count += 1
                rotation_count %= 4
            elif response & 0xFF == ord('q'):
                break
        break

    cv2.imshow('frame', frame)
    if cv2.waitKey(3) & 0xFF == ord('q'):
        break

cap.release()
cv2.destroyAllWindows()

# 检查是否完成棋盘检测，未完成则退出
if augmented_corners is None:
    print("未检测到棋盘，校准流程终止")
    sys.exit(0)

def euclidean_distance(first, second):
    return sqrt((first[0] - second[0]) ** 2 + (first[1] - second[1]) ** 2)


first_row = euclidean_distance(augmented_corners[1][1], augmented_corners[1][7])
last_row = euclidean_distance(augmented_corners[7][1], augmented_corners[7][7])
first_column = euclidean_distance(augmented_corners[1][1], augmented_corners[7][1])
last_column = euclidean_distance(augmented_corners[1][7], augmented_corners[7][7])

if abs(first_row - last_row) >= abs(first_column - last_column):
    if first_row >= last_row:
        side_view_compensation = (1, 0)
    else:
        side_view_compensation = (-1, 0)
else:
    if first_column >= last_column:
        side_view_compensation = (0, -1)
    else:
        side_view_compensation = (0, 1)

print("Side view compensation" + str(side_view_compensation))
print("Rotation count " + str(rotation_count))
filename = 'constants.bin'
outfile = open(filename, 'wb')
pickle.dump([augmented_corners, side_view_compensation, rotation_count, roi_mask], outfile)
outfile.close()

内容的提问来源于stack exchange，提问作者Veerasaroot Bunkangwan