Ruby script to convert WGS84(BLH) to ECEF coordinate.

blh2ecef.rb

#! /usr/local/bin/ruby
#---------------------------------------------------------------------------------
# BLH -> ECEF 変換
# : WGS84 の緯度(Beta)／経度(Lambda)／楕円体高(Height)を
#   ECEF（Earth Centered Earth Fixed; 地球中心・地球固定直交座標系）座標に
#   変換する。
#
# Date          Author          Version
# 2019.02.19    mk-mode.com     1.00 新規作成
#
# Copyright(C) 2019 mk-mode.com All Rights Reserved.
#---------------------------------------------------------------------------------
#
class ConvBlh2Ecef
  USAGE = "[USAGE] ./blh2ecef.rb LATITUDE(BETA) LONGITUDE(LAMBDA) HEIGHT"
  PI_180 = Math::PI / 180.0
  # WGS84 座標パラメータ
  A      = 6378137.0                # a(地球楕円体長半径(赤道面平均半径))
  ONE_F  = 298.257223563            # 1 / f(地球楕円体扁平率=(a - b) / a)
  B      = A * (1.0 - 1.0 / ONE_F)  # b(地球楕円体短半径)
  E2     = (1.0 / ONE_F) * (2 - (1.0 / ONE_F))
                                    # e^2 = 2 * f - f * f
                                    #     = (a^2 - b^2) / a^2
  ED2    = E2 * A * A / (B * B)     # e'^2= (a^2 - b^2) / b^2

  # Initialization
  # * コマンドライン引数の取得
  def initialize
    if ARGV.size < 3
      puts USAGE
      exit
    end
    @blh = ARGV[0, 3].map(&:to_f)
  end

  # Execution
  def exec
    puts "BLH: LATITUDE(BETA) = %12.8f°" % @blh[0]
    puts "  LONGITUDE(LAMBDA) = %12.8f°" % @blh[1]
    puts "             HEIGHT = %7.3fm"   % @blh[2]
    ecef = blh2ecef(@blh)
    puts "--->"
    puts "ECEF: X = %12.3fm" % ecef[0]
    puts "      Y = %12.3fm" % ecef[1]
    puts "      Z = %12.3fm" % ecef[2]
  rescue => e
    msg = "[#{e.class}] #{e.message}\n"
    e.backtrace.each { |tr| msg << "\t#{tr}\n" }
    $stderr.puts msg
    exit 1
  end

  private

  # BLH -> ECEF 変換
  #
  # @param   blh: BHL  座標 [latitude, longitude, height]
  # @return ecef: ECEF 座標 [x, y, z]
  def blh2ecef(blh)
    lat, lon, ht = blh
    n = lambda do |x|
      s = Math.sin(x * PI_180)
      A / Math.sqrt(1.0 - E2 * s * s)
    end
    x = (n.call(lat) + ht) \
      * Math.cos(lat * PI_180) \
      * Math.cos(lon * PI_180)
    y = (n.call(lat) + ht) \
      * Math.cos(lat * PI_180) \
      * Math.sin(lon * PI_180)
    z = (n.call(lat) * (1.0 - E2) + ht) \
      * Math.sin(lat * PI_180)
    return [x, y, z]
  rescue => e
    raise
  end
end

ConvBlh2Ecef.new.exec if __FILE__ == $0