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fronteer-kr/기상청 격자 <-> 위경도 변환

Last active March 17, 2025 14:40
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기상청 격자 <-> 위경도 변환
// 소스출처 : http://www.kma.go.kr/weather/forecast/digital_forecast.jsp 내부에 있음
// 기상청에서 이걸 왜 공식적으로 공개하지 않을까?
//
// (사용 예)
// var rs = dfs_xy_conv("toLL","60","127");
// console.log(rs.lat, rs.lng);
//
<script language="javascript">
//<!--
//
// LCC DFS 좌표변환을 위한 기초 자료
//
var RE = 6371.00877; // 지구 반경(km)
var GRID = 5.0; // 격자 간격(km)
var SLAT1 = 30.0; // 투영 위도1(degree)
var SLAT2 = 60.0; // 투영 위도2(degree)
var OLON = 126.0; // 기준점 경도(degree)
var OLAT = 38.0; // 기준점 위도(degree)
var XO = 43; // 기준점 X좌표(GRID)
var YO = 136; // 기1준점 Y좌표(GRID)
//
// LCC DFS 좌표변환 ( code : "toXY"(위경도->좌표, v1:위도, v2:경도), "toLL"(좌표->위경도,v1:x, v2:y) )
//
function dfs_xy_conv(code, v1, v2) {
var DEGRAD = Math.PI / 180.0;
var RADDEG = 180.0 / Math.PI;
var re = RE / GRID;
var slat1 = SLAT1 * DEGRAD;
var slat2 = SLAT2 * DEGRAD;
var olon = OLON * DEGRAD;
var olat = OLAT * DEGRAD;
var sn = Math.tan(Math.PI * 0.25 + slat2 * 0.5) / Math.tan(Math.PI * 0.25 + slat1 * 0.5);
sn = Math.log(Math.cos(slat1) / Math.cos(slat2)) / Math.log(sn);
var sf = Math.tan(Math.PI * 0.25 + slat1 * 0.5);
sf = Math.pow(sf, sn) * Math.cos(slat1) / sn;
var ro = Math.tan(Math.PI * 0.25 + olat * 0.5);
ro = re * sf / Math.pow(ro, sn);
var rs = {};
if (code == "toXY") {
rs['lat'] = v1;
rs['lng'] = v2;
var ra = Math.tan(Math.PI * 0.25 + (v1) * DEGRAD * 0.5);
ra = re * sf / Math.pow(ra, sn);
var theta = v2 * DEGRAD - olon;
if (theta > Math.PI) theta -= 2.0 * Math.PI;
if (theta < -Math.PI) theta += 2.0 * Math.PI;
theta *= sn;
rs['x'] = Math.floor(ra * Math.sin(theta) + XO + 0.5);
rs['y'] = Math.floor(ro - ra * Math.cos(theta) + YO + 0.5);
}
else {
rs['x'] = v1;
rs['y'] = v2;
var xn = v1 - XO;
var yn = ro - v2 + YO;
ra = Math.sqrt(xn * xn + yn * yn);
if (sn < 0.0) - ra;
var alat = Math.pow((re * sf / ra), (1.0 / sn));
alat = 2.0 * Math.atan(alat) - Math.PI * 0.5;
if (Math.abs(xn) <= 0.0) {
theta = 0.0;
}
else {
if (Math.abs(yn) <= 0.0) {
theta = Math.PI * 0.5;
if (xn < 0.0) - theta;
}
else theta = Math.atan2(xn, yn);
}
var alon = theta / sn + olon;
rs['lat'] = alat * RADDEG;
rs['lng'] = alon * RADDEG;
}
return rs;
}
//-->
</script>
@aims-och
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aims-och commented Mar 31, 2021 •
edited
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// C#입니다.
// 없어서 추가해봅니다.
// tuple 이 Dictionary<string, double>로 가능

        VilageFcstInfoSvc       vfis    =   new VilageFcstInfoSvc();
        vfis.GetData();


class WeatherApiCommon 
{
    /// <summary>
    /// 대기오염 정보조회 서비스
    /// 1 getMsrstnAcctoRltmMesureDnsty               측정소별 실시간 측정정보 조회
    /// 2 getUnityAirEnvrnIdexSnstiveAboveMsrstnList  통합대기환경지수 나쁨 이상 측정소 목록조회
    /// 3 getCtprvnRltmMesureDnsty                    시도별 실시간 측정정보 조회
    /// 4 getMinuDustFrcstDspth                       대기질 예보통보 조회
    /// 5 getCtprvnMesureLIst                         시도별 실시간 평균정보 조회
    /// 6 getCtprvnMesureSidoLIst                     시군구별 실시간 평균정보 조회
    /// </summary>
    /// <returns></returns>
    internal static string GetArpltnInforInqireSvcUrl( byte idx )
    {
        return @"http://openapi.airkorea.or.kr/openapi/services/rest/ArpltnInforInqireSvc/" + GetArpltnInforInqireSvcNm( idx ); 
    }

    /// <summary> 
    /// 오퍼레이션명(영문)
    /// </summary>
    /// <param name="idx">default -> 3</param>
    /// <returns></returns>
    private static string GetArpltnInforInqireSvcNm( byte idx )
    {  
        switch( idx )
        {
            case 1:
                return "getMsrstnAcctoRltmMesureDnsty";
            case 2:
                return "getUnityAirEnvrnIdexSnstiveAboveMsrstnList";
            case 3: default:
                return "getCtprvnRltmMesureDnsty";
            case 4:
                return "getMinuDustFrcstDspth";
            case 5:
                return "getCtprvnMesureLIst";
            case 6:
                return "getCtprvnMesureSidoLIst"; 
        } 
    }


    /// <summary>
    /// 동네예보 조회서비스
    /// 1 getUltraSrtNcst       초단가실황조회
    /// 2 getUltraSrtFcst       초단가예보조회
    /// 3 getVilageFcst         동네예보조회
    /// 4 getFcstVersion        예보버전조회
    /// </summary>
    /// <returns></returns>
    internal static string GetVilageFcstInfoSvcUrl( byte idx )
    {
        return @"http://apis.data.go.kr/1360000/VilageFcstInfoService/" + GetVilageFcstInfoSvcNm( idx ); 
    } 

    /// <summary> 
    /// 오퍼레이션명(영문)
    /// </summary>
    /// <param name="idx">default -> 3</param>
    /// <returns></returns>
    private static string GetVilageFcstInfoSvcNm( byte idx )
    {
        switch( idx )
        {
            case 1:
                return "getUltraSrtNcst";
            case 2:
                return "getUltraSrtFcst";
            case 3: default:
                return "getVilageFcst";
            case 4:
                return "getFcstVersion"; 
        } 
    } 
    
    /// <summary>
    /// 동네예보 조회서비스
    /// 1 getUltraSrtNcst       초단가실황조회
    /// 2 getUltraSrtFcst       초단가예보조회
    /// 3 getVilageFcst         동네예보조회
    /// 4 getFcstVersion        예보버전조회
    /// </summary>
    /// <returns></returns>
    internal static string GetBaseTime( byte idx )
    { 
        switch( idx )
        {
            case 1:
            {
                if( DateTime.Now < DateTime.Now.AddMinutes( 40 - DateTime.Now.Minute ) )
                    return DateTime.Now.AddHours(-1).ToString( "HH00" );
                else
                     return DateTime.Now.ToString( "HH00" );
            }
            case 2:
            { 
                if( DateTime.Now < DateTime.Now.AddMinutes( 45 - DateTime.Now.Minute ) )
                    return DateTime.Now.AddHours(-1).ToString( "HH00" );
                else
                     return DateTime.Now.ToString( "HH00" );
            }
            case 3:  case 4: default:
            {
                int hour = DateTime.Now.Hour;
                if (DateTime.Now < DateTime.Now.AddMinutes(10 - DateTime.Now.Minute))
                {
                    hour = DateTime.Now.AddHours(-1).Hour;
                }
                if (hour - 2 == 0)
                {
                    hour = 24;
                }
                int select = (hour - 2) / 3; 
                return GetBaseTimeSelect( select );
            } 
        }
    } 
    private static string GetBaseTimeSelect( int idx )
    {
        switch( idx )
        {
            case 0: default:
                return "0200";
            case 1:
                return "0500";
            case 2:
                return "0800";
            case 3:
                return "1100";
            case 4:
                return "1400";
            case 5:
                return "1700";
            case 6:
                return "2000";
            case 7:
                return "2300";
        }
    }

    /// <summary>
    /// 인증키
    /// 개발인증키만 받음상태 운영인증키는 현재 발급안한상태
    /// </summary>
    /// <param name="bDev">개발인증키여부</param>
    /// <returns></returns>
    internal static string GetAuthenticationkey( bool bDev = true )
    {
        if( bDev )
        {
            return "Authenticationkey";
        }
        else
        {
            return "Authenticationkey";
        }
    }
}


class VilageFcstInfoSvc : WeatherApiCommon
{
    
    private string GetUrl( bool bjson = true )
    {
        byte baseidx            =   3; 
        var tuplugrid           =   GetWeatherDigitalForecast( "toGRID", 37.579871128849334, 126.98935225645432 );
        //var tuplugrid2          =   GetWeatherDigitalForecast( "toGPS", 60, 127 );
        HttpClient  client      =   new HttpClient();
        string      basedate    =   DateTime.Now.ToString( "yyyyMMdd" );
        string      basetime    =   WeatherApiCommon.GetBaseTime( baseidx );
        string      serviceKey  =   GetAuthenticationkey(); 
        string      xmljson     =   bjson ? "JSON" : "XML";
        string      url         =   WeatherApiCommon.GetVilageFcstInfoSvcUrl( baseidx )+ $"?ServiceKey={serviceKey}&numOfRows=900&pageNo=1";
        return  url + $"&dataType={xmljson}&base_date={basedate}&base_time={basetime}&nx={tuplugrid.x}&ny={tuplugrid.y}";
             
    }
    
    public void GetData( bool bjson = false )
    {
        if( bjson )
            GetDataJson();
        else
            GetDataXml();
    }

    
    /// <summary>
    /// 동네예보조회
    /// </summary>
    public DataTable GetDataXml()
    {
        string      url         =   GetUrl(false);
        var         request     =   WebRequest.Create(url) as HttpWebRequest;
        request.Method          =   "GET";

        using( HttpWebResponse response = request.GetResponse() as HttpWebResponse )
        {
            var     stream      =   response.GetResponseStream();
            DataSet dts         =   new DataSet();
            dts.ReadXml( stream, XmlReadMode.InferSchema);                
            DataTable   dtt     =   dts.Tables["item"]; 
            return dtt;
        }  
    }

    /// <summary>
    /// 동네예보조회
    /// </summary>
    public JToken GetDataJson()
    {
        string      url         =   GetUrl();
        var         request     =   WebRequest.Create(url) as HttpWebRequest;
        request.Method          =   "GET";

        using( HttpWebResponse response = request.GetResponse() as HttpWebResponse )
        {
            var     reader      =   new StreamReader(response.GetResponseStream());
            string  results     =   reader.ReadToEnd();                
            JObject jObject     =   JObject.Parse( results );
            JToken  jList       =   jObject["response"]["body"]["items"]["item"]; 
            return jList;
        }
    }
    
    /// <summary>
    /// http://www.kma.go.kr/weather/forecast/digital_forecast.jsp 
    /// LCC DFS 좌표변환 
    /// toGRID : 위경도->좌표,  latX:위도,  lngY:경도
    /// toGPS  : 좌표->위경도,  latX:x,     lngY:y
    /// </summary>
    /// <param name="code"></param>
    /// <param name="latX"></param>
    /// <param name="lngY"></param>
    /// <returns></returns>
    /// private Dictionary<string, double> GetWeatherDigitalForecast( string code, double latX, double lngY )
    private ( double lat, double lng, double x, double y ) GetWeatherDigitalForecast( string code, double latX, double lngY )
    {
        double  ra;
        double  theta;
        double  RE      =   6371.00877;     // 지구 반경(km)
        double  GRID    =   5.0;            // 격자 간격(km)
        double  SLAT1   =   30.0;           // 투영 위도1(degree)
        double  SLAT2   =   60.0;           // 투영 위도2(degree)
        double  OLON    =   126.0;          // 기준점 경도(degree)
        double  OLAT    =   38.0;           // 기준점 위도(degree)
        double  XO      =   43;             // 기준점 X좌표(GRID)
        double  YO      =   136;            // 기1준점 Y좌표(GRID)

        double  DEGRAD  =   Math.PI / 180.0;
        double  RADDEG  =   180.0 / Math.PI;

        double  re      =   RE / GRID;
        double  slat1   =   SLAT1 * DEGRAD;
        double  slat2   =   SLAT2 * DEGRAD;
        double  olon    =   OLON  * DEGRAD;
        double  olat    =   OLAT  * DEGRAD;

        double  sn      =   Math.Tan( Math.PI * 0.25f + slat2 * 0.5f ) / Math.Tan( Math.PI * 0.25f + slat1 * 0.5f );
        sn              =   Math.Log( Math.Cos(slat1) / Math.Cos(slat2) ) / Math.Log(sn);
        double  sf      =   Math.Tan( Math.PI * 0.25f + slat1 * 0.5f );
        sf              =   Math.Pow( sf, sn ) * Math.Cos(slat1) / sn;
        double  ro      =   Math.Tan( Math.PI * 0.25f + olat * 0.5f );
        ro              =   re * sf / Math.Pow(ro, sn);
        
        if ( "toGRID".Equals( code ) )
        {
            ra          =   Math.Tan(Math.PI * 0.25f + (latX) * DEGRAD * 0.5f);
            ra          =   re * sf / Math.Pow(ra, sn);
            theta       =   lngY * DEGRAD - olon;
            if( theta > Math.PI ) 
                theta   -=  2.0f * Math.PI;
            if( theta < -Math.PI) 
                theta   +=  2.0f * Math.PI;
            theta       *=  sn;
            return ( latX, lngY, Math.Floor(ra * Math.Sin(theta) + XO + 0.5f), Math.Floor(ro - ra * Math.Cos(theta) + YO + 0.5f) );
        }
        else
        {
            double  xn  =   latX - XO;
            double  yn  =   ro - lngY + YO;
            ra          =   Math.Sqrt(xn * xn + yn * yn);
            if( sn < 0.0f ) 
                ra      =   -ra;
            double  alat    =   Math.Pow((re * sf / ra), (1.0f/ sn));
            alat            =   2.0f * Math.Atan(alat) - Math.PI * 0.5f;

            if( Math.Abs(xn) <= 0.0 )
                theta = 0.0f;
            else
            {
                if( Math.Abs(yn) <= 0.0 )
                {
                    theta   =   Math.PI * 0.5f;
                    if (xn < 0.0f) 
                        theta   =   -theta;
                }
                else 
                    theta   =   Math.Atan2(xn, yn);
            }
            double  alon    =   theta / sn + olon;  
            return ( alat * RADDEG, alon * RADDEG, latX, lngY );
        }
    }

}

@khjde1207
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khjde1207 commented Oct 18, 2021 •
edited
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flutter 용 공유해 볼께요. static 으로 만들었는데. 상황에 따라 변경해서 써야 할 수도 있어요.

var gridToGpsData = ConvGridGps.gridToGPS(60, 127);
var gpsToGridData = ConvGridGps.gpsToGRID(37.579871128849334, 126.98935225645432);
print(gridToGpsData);
print(gpsToGridData);

결과 :
I/flutter (27910): {x: 60, y: 127, lat: 37.61574148576467, lng: 126.98991183668376}
I/flutter (27910): {lat: 37.579871128849334, lng: 126.98935225645432, x: 60, y: 127}

import 'dart:math' as Math;

class ConvGridGps {
  static const double RE = 6371.00877; // 지구 반경(km)
  static const double GRID = 5.0; // 격자 간격(km)
  static const double SLAT1 = 30.0; // 투영 위도1(degree)
  static const double SLAT2 = 60.0; // 투영 위도2(degree)
  static const double OLON = 126.0; // 기준점 경도(degree)
  static const double OLAT = 38.0; // 기준점 위도(degree)
  static const double XO = 43; // 기준점 X좌표(GRID)
  static const double YO = 136; // 기1준점 Y좌표(GRID)

  static const double DEGRAD = Math.pi / 180.0;
  static const double RADDEG = 180.0 / Math.pi;

  static double get re => RE / GRID;
  static double get slat1 => SLAT1 * DEGRAD;
  static double get slat2 => SLAT2 * DEGRAD;
  static double get olon => OLON * DEGRAD;
  static double get olat => OLAT * DEGRAD;

  static double get snTmp =>
      Math.tan(Math.pi * 0.25 + slat2 * 0.5) /
      Math.tan(Math.pi * 0.25 + slat1 * 0.5);
  static double get sn =>
      Math.log(Math.cos(slat1) / Math.cos(slat2)) / Math.log(snTmp);

  static double get sfTmp => Math.tan(Math.pi * 0.25 + slat1 * 0.5);
  static double get sf => Math.pow(sfTmp, sn) * Math.cos(slat1) / sn;

  static double get roTmp => Math.tan(Math.pi * 0.25 + olat * 0.5);

  static double get ro => re * sf / Math.pow(roTmp, sn);

  static gridToGPS(int v1, int v2) {
    var rs = {};
    double theta;

    rs['x'] = v1;
    rs['y'] = v2;
    int xn = (v1 - XO).toInt();
    int yn = (ro - v2 + YO).toInt();
    var ra = Math.sqrt(xn * xn + yn * yn);
    if (sn < 0.0) ra = -ra;
    var alat = Math.pow((re * sf / ra), (1.0 / sn));
    alat = 2.0 * Math.atan(alat) - Math.pi * 0.5;

    if (xn.abs() <= 0.0) {
      theta = 0.0;
    } else {
      if (yn.abs() <= 0.0) {
        theta = Math.pi * 0.5;
        if (xn < 0.0) theta = -theta;
      } else
        theta = Math.atan2(xn, yn);
    }
    var alon = theta / sn + olon;
    rs['lat'] = alat * RADDEG;
    rs['lng'] = alon * RADDEG;

    return rs;
  }

  static gpsToGRID(double v1, double v2) {
    var rs = {};
    double theta;

    rs['lat'] = v1;
    rs['lng'] = v2;
    var ra = Math.tan(Math.pi * 0.25 + (v1) * DEGRAD * 0.5);
    ra = re * sf / Math.pow(ra, sn);
    theta = v2 * DEGRAD - olon;
    if (theta > Math.pi) theta -= 2.0 * Math.pi;
    if (theta < -Math.pi) theta += 2.0 * Math.pi;
    theta *= sn;
    rs['x'] = (ra * Math.sin(theta) + XO + 0.5).floor();
    rs['y'] = (ro - ra * Math.cos(theta) + YO + 0.5).floor();

    return rs;
  }
}

@koprodev
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koprodev commented May 23, 2022 •
edited
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// PHP 버전입니다.
// 위 [khjde1207]님의 flutter 버전을 참고했습니다.
// 결과

  $ConvGridGps = new ConvGridGps();
  $gridToGpsData = $ConvGridGps->gridToGPS(60,127);
  $gpsToGridData = $ConvGridGps->gpsToGRID(37.579871128849334, 126.98935225645432);
  print_r($gridToGpsData);
  print_r($gpsToGridData);

Array ( [x] => 60 [y] => 127 [lat] => 37.615741485765 [lng] => 126.98991183668 )
Array ( [lat] => 37.579871128849 [lng] => 126.98935225645 [x] => 60 [y] => 127 )

class ConvGridGps {
	const RE = 6371.00877; // 지구 반경(km)
	const GRID = 5.0; // 격자 간격(km)
	const SLAT1 = 30.0; // 투영 위도1(degree)
	const SLAT2 = 60.0; // 투영 위도2(degree)
	const OLON = 126.0; // 기준점 경도(degree)
	const OLAT = 38.0; // 기준점 위도(degree)
	const XO = 43; // 기준점 X좌표(GRID)
	const YO = 136; // 기1준점 Y좌표(GRID)

	const DEGRAD = M_PI / 180.0;
	const RADDEG = 180.0 / M_PI;

	const re = self::RE / self::GRID;
	const slat1 = self::SLAT1 * self::DEGRAD;
	const slat2 = self::SLAT2 * self::DEGRAD;
	const olon = self::OLON * self::DEGRAD;
	const olat = self::OLAT * self::DEGRAD;

	function sn(){
		$snTmp = tan(M_PI * 0.25 + self::slat2 * 0.5) / tan(M_PI * 0.25 + self::slat1 * 0.5);
		return log(cos(self::slat1) / cos(self::slat2)) / log($snTmp);
	}

	function sf(){
		$sfTmp = tan(M_PI * 0.25 + self::slat1 * 0.5);
		return pow($sfTmp, $this->sn()) * cos(self::slat1) / $this->sn();
	}

	function ro(){
		$roTmp = tan(M_PI * 0.25 + self::olat * 0.5);
		return self::re * $this->sf() / pow($roTmp, $this->sn());
	}

	function gridToGPS($v1, $v2) {
	  $rs['x'] = $v1;
	  $rs['y'] = $v2;
	  $xn = (int)($v1 - self::XO);
	  $yn = (int)($this->ro() - $v2 + self::YO);
	  $ra = sqrt($xn * $xn + $yn * $yn);
	  if ($this->sn() < 0.0) $ra = -$ra;
	  $alat = pow((self::re * $this->sf() / $ra), (1.0 / $this->sn()));
	  $alat = 2.0 * atan($alat) - M_PI * 0.5;

	  if (abs($xn) <= 0.0) {
		$theta = 0.0;
	  } else {
		if (abs($yn) <= 0.0) {
		  $theta = M_PI * 0.5;
		  if ($xn < 0.0) $theta = -$theta;
		} else
		  $theta = atan2($xn, $yn);
	  }
	  $alon = $theta / $this->sn() + self::olon;
	  $rs['lat'] = $alat * self::RADDEG;
	  $rs['lng'] = $alon * self::RADDEG;

	  return $rs;
	}

	function gpsToGRID($v1, $v2) {
	  $rs['lat'] = $v1;
	  $rs['lng'] = $v2;
	  $ra = tan(M_PI * 0.25 + ($v1) * self::DEGRAD * 0.5);
	  $ra = self::re * $this->sf() / pow($ra, $this->sn());
	  $theta = $v2 * self::DEGRAD - self::olon;
	  if ($theta > M_PI) $theta -= 2.0 * M_PI;
	  if ($theta < -M_PI) $theta += 2.0 * M_PI;
	  $theta *= $this->sn();
	  $rs['x'] = floor(($ra * sin($theta) + self::XO + 0.5));
	  $rs['y'] = floor(($this->ro() - $ra * cos($theta) + self::YO + 0.5));

	  return $rs;
	}
  }

@Dong-Yeob-Yu
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[dalku] 님의 Java -> Kotlin 입니다.

mode 1 + 위도, 경우 입력시 -> 격자x, 격자y 출력
mode 0 + 격자x, 격자 y 입력시 -> lat 위도, lng 경도 출력

const val MODE_GRID = 1;
const val MODE_GPS = 0;

public fun convertGRID_GPS(mode: Int, lat: Double, lng: Double): LatXLngY {

    // 지구 반경(km)
    val RE: Double = 6371.00877
    // 격자 간격(km)
    val GRID: Double = 5.0
    // 투영 위도1(degree)
    val SLAT1: Double = 30.0
    // 투영 위도2(degree)
    val SLAT2: Double = 60.0
    // 기준점 경도(degree)
    val OLON: Double = 126.0
    // 기준점 위도(degree)
    val OLAT: Double = 38.0
    // 기준점 X좌표(GRID)
    val XO: Double = 43.0
    // 기준점 Y좌표(GRID)
    val YO: Double = 136.0

    val DEGRAD = Math.PI / 180.0
    val RADDEG = 180.0 / Math.PI

    val re = RE / GRID
    val slat1 = SLAT1 * DEGRAD
    val slat2 = SLAT2 * DEGRAD
    val olon = OLON * DEGRAD
    val olat = OLAT * DEGRAD

    var sn = tan(Math.PI * 0.25 + slat2 * 0.5) / tan(Math.PI * 0.25 + slat1 * 0.5)
    sn = ln(cos(slat1) / cos(slat2)) / ln(sn)

    var sf = tan(Math.PI * 0.25 + slat1 * 0.5)
    sf = sf.pow(sn) * cos(slat1) / sn

    var ro = tan(Math.PI * 0.25 + olat * 0.5)
    ro = re * sf / ro.pow(sn)

    val rs = LatXLngY()

    if (mode == MODE_GRID) {
        rs.lat = lat
        rs.lng = lng
        var ra = tan(Math.PI * 0.25 + lat * DEGRAD * 0.5)
        ra = re * sf / ra.pow(sn)
        var theta = lng * DEGRAD - olon
        if (theta > Math.PI) theta -= 2.0 * Math.PI
        if (theta < -Math.PI) theta += 2.0 * Math.PI
        theta *= sn
        rs.x = floor(ra * sin(theta) + XO + 0.5)
        rs.y = floor(ro - ra * cos(theta) + YO + 0.5)
    } else {
        rs.x = lat
        rs.y = lng
        val xn = lat - XO
        val yn = ro - lng + YO
        var ra = sqrt(xn * xn + yn * yn)
        if (sn < 0.0) {
            ra = -ra
        }
        var alat = (re * sf / ra).pow(1.0 / sn)
        alat = 2.0 * atan(alat) - Math.PI * 0.5

        var theta = 0.0
        if (abs(xn) <= 0.0) {
            theta = 0.0
        } else {
            if (abs(yn) <= 0.0) {
                theta = Math.PI * 0.5
                if (xn < 0.0) {
                    theta = -theta
                }
            } else {
                theta = atan2(xn, yn)
            }
        }
        val alon = theta / sn + olon
        rs.lat = alat * RADDEG
        rs.lng = alon * RADDEG
    }
    return rs
}


data class LatXLngY(
    var lat: Double? = null,
    var lng: Double? = null,

    var x: Double? = null,
    var y: Double? = null,
)

@frogio
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frogio commented Mar 17, 2025

원래 공식적으로 공개했습니다. 기상청에서 C언어로 작성해서 문서에 올려놓았어요.
찾아보면 있어요

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