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# SPDX-License-Identifier: GPL-2.0-or-later
from math import sin, cos, atan, atanh, radians, tan, sinh, asin, cosh, degrees
# see conversion formulas at
# http://en.wikipedia.org/wiki/Transverse_Mercator_projection
# http://mathworld.wolfram.com/MercatorProjection.html
class TransverseMercator:
radius = 6378137
def __init__(self, lat=0, lon=0):
self.lat = lat # in degrees
self.lon = lon # in degrees
self.lat_rad = radians(self.lat)
self.lon_rad = radians(self.lon)
def fromGeographic(self, lat, lon):
lat_rad = radians(lat)
lon_rad = radians(lon)
B = cos(lat_rad) * sin(lon_rad - self.lon_rad)
x = self.radius * atanh(B)
y = self.radius * (atan(tan(lat_rad) / cos(lon_rad - self.lon_rad)) - self.lat_rad)
return x, y
def toGeographic(self, x, y):
x /= self.radius
y /= self.radius
D = y + self.lat_rad
lon = atan(sinh(x) / cos(D))
lat = asin(sin(D) / cosh(x))
lon = self.lon + degrees(lon)
lat = degrees(lat)
return lat, lon
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