沿 y 轴逐行旋转（对齐）图像

Question

我正在尝试旋转（对齐）图像，其中P1包含P2沿y-axis原图：注：绿色区域代表原图结果应该是：注：红色区域代表旋转后的原图所以我需要计算由P1(x1,y1)andP2(x2,y2)和 by定义的线之间的角度y-axis，我的代码是：import cv2import numpy as npfrom math import *import mathimport imutilsheight = 500width = 500original_image = np.zeros((height,width,3), np.uint8)original_image[:] = (0,255,0)x1 = 400y1 = 50P1 = (x1, y1)x2 = 100y2 = 300P2 = (x2, y2)cv2.line(original_image, P1, P2, (0, 0, 0), 3)deltaY = y1 - y2deltaX = x1 - x2angleInDegrees = atan2(deltaY, deltaX) * 180 / math.piprint(angleInDegrees)rotated_image = imutils.rotate_bound(original_image, angleInDegrees)cv2.imshow("Original", original_image)cv2.imshow("Rotated", rotated_image)cv2.waitKey(0)但是我的rotated_image 没有正确对齐结果如下：我应该如何解决它？

Answer 1

首先，您正在计算错误的角度。您正在计算的角度介于起源于原点并结束于 P1 的向量与起源于原点并结束于 P2 的向量之间。

您需要的角度介于从 P1 开始到 P2 结束[P2-P1]的向量与表示 y 轴方向的向量之间，即[0, 1].

其次，您必须考虑到您的原点位于左上角，因此您需要在计算后反映角度。

import cv2

import numpy as np

from math import *

import math

import imutils

height = 500

width  = 500

original_image = np.zeros((height,width,3), np.uint8)

original_image[:] = (0,255,0)

x1 = 400 

y1 = 50

P1 = np.array([x1, y1])

x2 = 100

y2 = 300

P2 = np.array([x2, y2])

# checks orientation of p vector & selects appropriate y_axis_vector

if (P2[1] - P1[1]) < 0:

    y_axis_vector = np.array([0, -1])

else:

    y_axis_vector = np.array([0, 1])

if (P2[0] - P1[0]) < 0 and (P2[1] - P1[1]) :

    y_axis_vector = np.array([0, 1])

p_unit_vector = (P2 - P1) / np.linalg.norm(P2-P1)

angle_p_y     = np.arccos(np.dot(p_unit_vector, y_axis_vector)) * 180 /math.pi

cv2.line(original_image, tuple(P1), tuple(P2), (0, 0, 0), 3)

print(angle_p_y)

print (P2-P1)

rotated_image = imutils.rotate_bound(original_image, -angle_p_y)

cv2.imshow("Original", original_image)

cv2.imshow("Rotated", rotated_image)

cv2.waitKey(0)