Opencv-Python图像透视变换cv2.warpPerspective的示例


						Opencv-Python图像透视变换cv2.warpPerspective

代码如下：





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

import cv2

import numpy as np

import sys

img = cv2.imread('test.jpg')

# cv2.imshow("original", img)

# 可选，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

r = 0

def rad(x):

  return x * np.pi / 180

def get_warpR():

  global anglex,angley,anglez,fov,w,h,r

  # 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)

  return warpR

def control():

  global anglex,angley,anglez,fov,r

  # 键盘控制

  if 27 == c: # Esc quit

    sys.exit()

  if c == ord('w'):

    anglex += 1

  if c == ord('s'):

    anglex -= 1

  if c == ord('a'):

    angley += 1

    print(angley)

    # 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('e'):

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

    print('Rotation Matrix:')

    print(r)

    print('angle alpha(anglex):')

    print(anglex)

    print('angle beta(angley):')

    print(angley)

    print('dz(anglez):')

    print(anglez)

while True:

  warpR = get_warpR()

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

  cv2.namedWindow('result',2)

  cv2.imshow("result", result)

  c = cv2.waitKey(30)

  control()

cv2.destroyAllWindows()



运行效果：



控制：



  s控制垂直方向上的形变

  a和d控制水平方向上的行变

  u和p控制角度旋转

  e 输出当前旋转矩阵参数



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