Class: Breasal::LatLng

Inherits:
Object
  • Object
show all
Includes:
Utils
Defined in:
lib/breasal/latlng.rb

Instance Method Summary collapse

Methods included from Utils

#cos_pow_2, #deg_to_rad, #rad_to_deg, #sec, #sin_pow_2, #tan_pow_2

Constructor Details

#initialize(options) ⇒ LatLng

Returns a new instance of LatLng.



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# File 'lib/breasal/latlng.rb', line 7

def initialize(options)
  @latitude = options[:latitude]
  @longitude = options[:longitude]
  @type = options[:type] || :gb
end

Instance Method Details

#to_WGS84 ⇒ Object

and returns WGS84 Latitude and Longitude



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# File 'lib/breasal/latlng.rb', line 15

def to_WGS84
 
 if @type == :ie
   @a        = 6377340.189
   @b        = 6356034.447
  else
    @a        = 6377563.396
    @b        = 6356256.909
  end
  
  @eSquared = ((@a * @a) - (@b * @b)) / (@a * @a)

  @phi = deg_to_rad(@latitude)
  @lambda = deg_to_rad(@longitude)
  @v = @a / (Math.sqrt(1 - @eSquared * sin_pow_2(@phi)))
  @H = 0
  @x = (@v + @H) * Math.cos(@phi) * Math.cos(@lambda)
  @y = (@v + @H) * Math.cos(@phi) * Math.sin(@lambda)
  @z = ((1 - @eSquared) * @v + @H) * Math.sin(@phi)

  @tx =        446.448
  @ty =       -124.157
  @tz =        542.060
  
  @s  =         -0.0000204894
  @rx = deg_to_rad( 0.00004172222)
  @ry = deg_to_rad( 0.00006861111)
  @rz = deg_to_rad( 0.00023391666)

  @xB = @tx + (@x * (1 + @s)) + (-@rx * @y)     + (@ry * @z)
  @yB = @ty + (@rz * @x)      + (@y * (1 + @s)) + (-@rx * @z)
  @zB = @tz + (-@ry * @x)     + (@rx * @y)      + (@z * (1 + @s))

  @a        = 6378137.000
  @b        = 6356752.3141
  @eSquared = ((@a * @a) - (@b * @b)) / (@a * @a)

  @lambdaB = rad_to_deg(Math.atan(@yB / @xB))
  @p = Math.sqrt((@xB * @xB) + (@yB * @yB))
  @phiN = Math.atan(@zB / (@p * (1 - @eSquared)))
  
  (1..10).each do |i|
    @v = @a / (Math.sqrt(1 - @eSquared * sin_pow_2(@phiN)))
    @phiN1 = Math.atan((@zB + (@eSquared * @v * Math.sin(@phiN))) / @p)
    @phiN = @phiN1
  end

  @phiB = rad_to_deg(@phiN)

  { :latitude => @phiB, :longitude => @lambdaB }
     
end