1 files changed, 54 insertions, 0 deletions
diff --git a/io_import_dxf/transverse_mercator.py b/io_import_dxf/transverse_mercator.py
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+++ b/io_import_dxf/transverse_mercator.py
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+# ##### BEGIN GPL LICENSE BLOCK #####
+#
+#  This program is free software; you can redistribute it and/or
+#  modify it under the terms of the GNU General Public License
+#  as published by the Free Software Foundation; either version 2
+#  of the License, or (at your option) any later version.
+#
+#  This program is distributed in the hope that it will be useful,
+#  but WITHOUT ANY WARRANTY; without even the implied warranty of
+#  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+#  GNU General Public License for more details.
+#
+#  You should have received a copy of the GNU General Public License
+#  along with this program; if not, write to the Free Software Foundation,
+#  Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
+#
+# ##### END GPL LICENSE BLOCK #####
+
+# <pep8 compliant>
+
+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