Module: Etrstm35fin

Defined in:
lib/etrstm35fin.rb,
lib/etrstm35fin/version.rb

Constant Summary collapse

WGS84_MAJOR = 
6378137.0
WGS84_MINOR = 
6356752.314245
FLATTENING = 
1.0 / 298.257223563
SCALE_FACTOR = 
0.9996
FALSE_EASTING = 
500000.0
FALSE_NORTHING = 
0.0
CENTRAL_MERIDIAN = 
27.0
VERSION = 
"0.0.1"

Class Method Summary collapse

Class Method Details

.to_degrees(val) ⇒ Object 



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# File 'lib/etrstm35fin.rb', line 53

def self.to_degrees(val)
  (val  * 180.0) / Math::PI
end

.to_radians(degree) ⇒ Object 



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# File 'lib/etrstm35fin.rb', line 57

def self.to_radians(degree)
  degree * (Math::PI / 180)
end

.to_wgs84(north_coordinate, east_coordinate) ⇒ Object 



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# File 'lib/etrstm35fin.rb', line 13

def self.to_wgs84(north_coordinate, east_coordinate)
  central_meridian = to_radians(CENTRAL_MERIDIAN)

  n = FLATTENING / (2.0 - FLATTENING)
  a1 = WGS84_MAJOR / (1.0 + n) * (1.0 + (n**2.0) / 4.0 + (n**4.0) / 64.0)
  e = Math.sqrt(2.0 * FLATTENING - (FLATTENING**2.0))
  h1 = 1.0 / 2.0 * n - 2.0 / 3.0 * (n**2.0) + 37.0/96.0 * (n**3.0) - 1.0/360.0 * (n**4.0)
  h2 = 1.0 / 48.0 * (n**2.0) + 1.0/15.0 * (n**3.0) - 437.0/1440.0 * (n**4.0)
  h3 = 17.0 / 480.0 * (n**3.0) - 37.0 / 840.0 * (n**4.0)
  h4 = 4397.0 / 161280.0 * (n**4.0)

  ee = north_coordinate / (a1 * SCALE_FACTOR)
  nn = (east_coordinate - FALSE_EASTING) / (a1 * SCALE_FACTOR)

  e1p = h1 * Math.sin(2.0 * ee) * Math.cosh(2.0 * nn)
  e2p = h2 * Math.sin(4.0 * ee) * Math.cosh(4.0 * nn)
  e3p = h3 * Math.sin(6.0 * ee) * Math.cosh(6.0 * nn)
  e4p = h4 * Math.sin(8.0 * ee) * Math.cosh(8.0 * nn)

  nn1p = h1 * Math.cos(2.0 * ee) * Math.sinh(2.0 * nn)
  nn2p = h2 * Math.cos(4.0 * ee) * Math.sinh(4.0 * nn)
  nn3p = h3 * Math.cos(6.0 * ee) * Math.sinh(6.0 * nn)
  nn4p = h4 * Math.cos(8.0 * ee) * Math.sinh(8.0 * nn)

  ep = ee - e1p - e2p - e3p - e4p

  nnp = nn - nn1p - nn2p - nn3p - nn4p
  be = Math.asin(Math.sin(ep) / Math.cosh(nnp))

  q = CMath.asinh(Math.tan(be))
  qp = q + e * CMath.atanh(e * Math.tanh(q))
  qp = q + e * CMath.atanh(e * Math.tanh(qp))
  qp = q + e * CMath.atanh(e * Math.tanh(qp))
  qp = q + e * CMath.atanh(e * Math.tanh(qp))

  lat = to_degrees(Math.atan(Math.sinh(qp)))
  lon = to_degrees(central_meridian + Math.asin(Math.tanh(nnp) / Math.cos(be)))
  [lat, lon]
end