python实现高斯投影正反算方式

使用python实现了一下我们同事的c++高斯投影正反算，实际跑通，可用。

#!/ usr/bin/python
# -*- coding:utf-8 -*-

import math


def latlon2xy(latitude, longitude):
  a = 6378137.0
  # b = 6356752.3142
  # c = 6399593.6258
  # alpha = 1 / 298.257223563
  e2 = 0.0066943799013
  # epep = 0.00673949674227


  #将经纬度转换为弧度
  latitude2rad = (math.pi / 180.0) * latitude

  beltno = int((longitude + 1.5) / 3.0) #计算3度带投影度带号
  l = beltno * 3 #计算*经线
  l0 = longitude - l #经差
  tsin = math.sin(latitude2rad)
  tcos = math.cos(latitude2rad)
  t = math.tan(latitude2rad)
  m = (math.pi / 180.0) * l0 * tcos
  et2 = e2 * pow(tcos, 2)
  et3 = e2 * pow(tsin, 2)
  x = 111132.9558 * latitude - 16038.6496 * math.sin(2 * latitude2rad) + 16.8607 * math.sin(
    4 * latitude2rad) - 0.0220 * math.sin(6 * latitude2rad)
  n = a / math.sqrt(1 - et3)

  x = x + n * t * (0.5 * pow(m, 2) + (5.0 - pow(t, 2) + 9.0 * et2 + 4 * pow(et2, 2)) * pow(m, 4) / 24.0 + (
  61.0 - 58.0 * pow(t, 2) + pow(t, 4)) * pow(m, 6) / 720.0)
  y = 500000 + n * (m + (1.0 - pow(t, 2) + et2) * pow(m, 3) / 6.0 + (
  5.0 - 18.0 * pow(t, 2) + pow(t, 4) + 14.0 * et2 - 58.0 * et2 * pow(t, 2)) * pow(m, 5) / 120.0)

  return x, y


def xy2latlon(x, y, l0):

  ipi = 0.0174532925199433
  a = 6378137.0
  f= 0.00335281006247
  zonewide = 3 #按3度带进行投影

  projno = int(x / 1000000)
  l0 = l0 * ipi
  x0 = projno * 1000000 + 500000
  y0 = 0
  xval = x - x0
  yval = y - y0

  e2 = 2 * f - f * f #第一偏心率平方
  e1 = (1.0 - math.sqrt(1 - e2)) / (1.0 + math.sqrt(1 - e2))
  ee = e2 / (1 - e2) #第二偏心率平方

  m = yval
  u = m / (a * (1 - e2 / 4 - 3 * e2 * e2 / 64 - 5 * e2 * e2 * e2 / 256))

  fai = u \
     + (3 * e1 / 2 - 27 * e1 * e1 * e1 / 32) * math.sin(2 * u) \
     + (21 * e1 * e1 / 16 - 55 * e1 * e1 * e1 * e1 / 32) * math.sin(4 * u) \
     + (151 * e1 * e1 * e1 / 96) * math.sin(6 * u)\
     + (1097 * e1 * e1 * e1 * e1 / 512) * math.sin(8 * u)
  c = ee * math.cos(fai) * math.cos(fai)
  t = math.tan(fai) * math.tan(fai)
  nn = a / math.sqrt(1.0 - e2 * math.sin(fai) * math.sin(fai))
  r = a * (1 - e2) / math.sqrt(
    (1 - e2 * math.sin(fai) * math.sin(fai)) * (1 - e2 * math.sin(fai) * math.sin(fai)) * (1 - e2 * math.sin(fai) * math.sin(fai)))
  d = xval / nn

  #计算经纬度（弧度单位的经纬度）
  longitude1 = l0 + (d - (1 + 2 * t + c) * d * d * d / 6 + (
  5 - 2 * c + 28 * t - 3 * c * c + 8 * ee + 24 * t * t) * d * d * d * d * d / 120) / math.cos(fai)
  latitude1 = fai - (nn * math.tan(fai) / r) * (
  d * d / 2 - (5 + 3 * t + 10 * c - 4 * c * c - 9 * ee) * d * d * d * d / 24 + (
  61 + 90 * t + 298 * c + 45 * t * t - 256 * ee - 3 * c * c) * d * d * d * d * d * d / 720)

  #换换为deg
  longitude = longitude1 / ipi
  latitude = latitude1 / ipi

  return latitude, longitude

# 
# print latlon2xy(40.07837722329, 116.23514827596)
# print xy2latlon(434760.7611718801, 4438512.040474475, 117.0)

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