python透视变换原理_python opencv实现任意角度的透视变换实例代码

本文主要分享的是一则python+opencv实现任意角度的透视变换的实例，具体如下：

# -*- coding:utf-8 -*-

import cv2

import numpy as np

def rad(x):

return x * np.pi / 180

img = cv2.imread("6.jfif")

cv2.imshow("original", img)

# 扩展图像，保证内容不超出可视范围

img = cv2.copyMakeBorder(img, 200, 200, 200, 200, cv2.BORDER_CONSTANT, 0)

w, h = img.shape[0:2]

anglex = 0

angley = 30

anglez = 0 #是旋转

fov = 42

while 1:

# 镜头与图像间的距离，21为半可视角，算z的距离是为了保证在此可视角度下恰好显示整幅图像

z = np.sqrt(w ** 2 + h ** 2) / 2 / np.tan(rad(fov / 2))

# 齐次变换矩阵

rx = np.array([[1, 0, 0, 0],

[0, np.cos(rad(anglex)), -np.sin(rad(anglex)), 0],

[0, -np.sin(rad(anglex)), np.cos(rad(anglex)), 0, ],

[0, 0, 0, 1]], np.float32)

ry = np.array([[np.cos(rad(angley)), 0, np.sin(rad(angley)), 0],

[0, 1, 0, 0],

[-np.sin(rad(angley)), 0, np.cos(rad(angley)), 0, ],

[0, 0, 0, 1]], np.float32)

rz = np.array([[np.cos(rad(anglez)), np.sin(rad(anglez)), 0, 0],

[-np.sin(rad(anglez)), np.cos(rad(anglez)), 0, 0],

[0, 0, 1, 0],

[0, 0, 0, 1]], np.float32)

r = rx.dot(ry).dot(rz)

# 四对点的生成

pcenter = np.array([h / 2, w / 2, 0, 0], np.float32)

p1 = np.array([0, 0, 0, 0], np.float32) - pcenter

p2 = np.array([w, 0, 0, 0], np.float32) - pcenter

p3 = np.array([0, h, 0, 0], np.float32) - pcenter

p4 = np.array([w, h, 0, 0], np.float32) - pcenter

dst1 = r.dot(p1)

dst2 = r.dot(p2)

dst3 = r.dot(p3)

dst4 = r.dot(p4)

list_dst = [dst1, dst2, dst3, dst4]

org = np.array([[0, 0],

[w, 0],

[0, h],

[w, h]], np.float32)

dst = np.zeros((4, 2), np.float32)

# 投影至成像平面

for i in range(4):

dst[i, 0] = list_dst[i][0] * z / (z - list_dst[i][2]) + pcenter[0]

dst[i, 1] = list_dst[i][1] * z / (z - list_dst[i][2]) + pcenter[1]

warpR = cv2.getPerspectiveTransform(org, dst)

result = cv2.warpPerspective(img, warpR, (h, w))

cv2.imshow("result", result)

c = cv2.waitKey(30)

# anglex += 3 #auto rotate

# anglez += 1 #auto rotate

# angley += 2 #auto rotate

# 键盘控制

if 27 == c: # Esc quit

break;

if c == ord('w'):

anglex += 1

if c == ord('s'):

anglex -= 1

if c == ord('a'):

angley += 1

# dx=0

if c == ord('d'):

angley -= 1

if c == ord('u'):

anglez += 1

if c == ord('p'):

anglez -= 1

if c == ord('t'):

fov += 1

if c == ord('r'):

fov -= 1

if c == ord(' '):

anglex = angley = anglez = 0

if c == ord('q'):

print("======================================")

print('旋转矩阵：\n', r)

print("angle alpha: ", anglex, 'angle beta: ', angley, "dz: ", anglez, ": ", z)

cv2.destroyAllWindows()

总结

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