Transformations

Transform coordinates between various coordinate systems used in Bulgaria.

Info
Install
Ellipsoids
Projections
Examples
Dependencies
Tests
License

Info

This project is based on Transformations.NET library.

The project can be used for transforming coordinates between various coordinate systems:

BGS 1930
BGS 1950
BGS Sofia
BGS 1970 (there can be no control points near by if the point is close to the zone's border)
BGS 2005

Following projections are available:

Lambert Conformal Conic with 2SP
Universal Transverse Mercator
Gauss–Krüger
Spherical Web Mercator

You can transform between:

Geographic coordinates
Projected coordinates
Geocentric coordinates

Transformations between BGS coordinate systems are done by calculating transformation parameters using TPS or Affine transformation based on predefined control points (ControlPoints namespace). You can control what type of transformation is used by passing useTPS boolean parameter to BGSCoordinates.transform(). All other transformations are done directly as the transformation parameters are known. Precision is arround 10cm.

Install

You can install it with NPM (npm install transformations) or Yarn (yarn add transformations) and then import a desired transformation function:

import { transformGeographicToUTM } from 'transformations';
 
const input = [42.450682, 24.749747];
const result = transformGeographicToUTM(input);

Ellipsoids

import { ellipsoids } from 'transformations';

GRS80 - GRS 1980
BESSEL_1841 - Bessel 1841
CLARKE_1866 - Clarke 1866
EVEREST - Everest (Sabah and Sarawak)
HELMERT - Helmert 1906
HAYFORD - Hayford
KRASSOVSKY - Krassovsky, 1942
WALBECK - Walbeck
WGS72 - WGS 1972
WGS84 - WGS 1984
SPHERE - Normal Sphere (R=6378137)

Projections

import { projections } from 'transformations';

BGS_SOFIA - BGS Sofia. Local projection based on BGS 1950
BGS_1930_24 - Gauss–Krüger projection based on Hayford ellipsoid
BGS_1930_27 - Gauss–Krüger projection based on Hayford ellipsoid
BGS_1950_3_24 - Gauss–Krüger projection based on Krassovsky ellipsoid
BGS_1950_3_27 - Gauss–Krüger projection based on Krassovsky ellipsoid
BGS_1950_6_21 - Gauss–Krüger projection based on Krassovsky ellipsoid
BGS_1950_6_27 - Gauss–Krüger projection based on Krassovsky ellipsoid
BGS_1970_K3 - ~ Northewest Bulgaria
BGS_1970_K5 - ~ Southeast Bulgaria
BGS_1970_K7 - ~ Northeast Bulgaria
BGS_1970_K9 - ~ Southwest Bulgaria
BGS_2005_KK - Lambert Conformal Conic with 2SP used by Cadastral Agency
UTM34N - Universal Transverse Mercator zone 34 North
UTM35N - Universal Transverse Mercator zone 35 North

Examples

Transform between geographic coordinates and projected in Lambert projection

import { transformGeographicToLambert, transformLambertToGeographic } from 'transformations';
 
let input = [42.7589996, 25.3799991];
let result = transformGeographicToLambert(input);
// result is: 4735953.342, 490177.508
 
let input = [4735953.349, 490177.508;
let result = transformLambertToGeographic(input);
// result is: 42.7589997, 25.3799991

Transform between geographic coordinates and projected in UTM

import { transformGeographicToUTM, transformUTMToGeographic } from 'transformations';
 
let input = [42.450682, 24.749747];
let result = transformGeographicToUTM(input);
// result is: 4702270.178, 314955.869
 
let input = [4702270.179, 314955.869];
let result = transformUTMToGeographic(input);
// result is: 42.450682, 24.749747

Transform between geographic coordinates and projected in Gauss–Krüger

import { transformGeographicToGauss, transformGaussToGeographic } from 'transformations';
 
let input = [42.7602978166667, 25.3824052611111];
let result = transformGeographicToGauss(input);
// result is: 4736629.503, 8613154.606
 
let input = [4736629.503, 8613154.607);
let result = transformGaussToGeographic(input);
// result is: 42.7602978, 25.38240528

Transform between geographic coordinates and projected in Web Mercator

import { transformGeographicToWebMercator, transformWebMercatorToGeographic } from 'transformations';
 
let input = [42.450682, 24.749747];
let result = transformGeographicToWebMercator(input);
// result is: 2755129.233, 5228730.328
 
let input = [2755129.23, 5228730.33];
let result = transformWebMercatorToGeographic(input);
// result is: 42.4506820, 24.7497470

Transform between geographic and geocentric coordinates

import { transformGeographicToGeocentric, transformGeocentricToGeographic } from 'transformations';
 
let input = [42.450682, 24.749747];
let result = transformGeographicToGeocentric(input);
// result is: X: 4280410.654, 1973273.422, 4282674.061
 
let input = [4280410.654, 1973273.422, 4282674.061];
let result = transformGeocentricToGeographic(input);
// result is: 42.450682, 24.749747

Transform between BGS coordinates

BGS 1930

import { BGSCoordinates } from 'transformations';
 
const bgs = new BGSCoordinates();
 
let input = [4728966.163, 8607005.227];
let result = bgs.transform(input, projections.BGS_1930_24, projections.BGS_2005_KK);
// result is: 4728401.432, 483893.508
 
let input = [4728401.432, 483893.508];
let result = bgs.transform(input, projections.BGS_2005_KK, projections.BGS_1930_24);
// result is: 4728966.153, 8607005.214

BGS 1950

import { BGSCoordinates } from 'transformations';
 
const bgs = new BGSCoordinates();
 
let input = [4729331.175, 8606933.614];
let result = bgs.transform(input, projections.BGS_1950_3_24, projections.BGS_2005_KK);
// result is: 4728401.442, 483893.521
 
let input = [4728401.432, 483893.508];
let result = tr.transform(input, projections.BGS_2005_KK, projections.BGS_1950_3_24);
// result is: 4729331.165, 8606933.601

BGS Sofia

import { BGSCoordinates } from 'transformations';
 
const bgs = new BGSCoordinates();
 
let input = [48276.705, 45420.988];
let result = bgs.transform(input, projections.BGS_SOFIA, projections.BGS_2005_KK);
// result is: 4730215.221, 322402.929
 
let input = [4730215.229, 322402.935];
let result = bgs.transform(input, projections.BGS_2005_KK, projections.BGS_SOFIA);
// result is: 48276.713, 45420.993

BGS 1970

import { BGSCoordinates } from 'transformations';
 
const bgs = new BGSCoordinates();
 
let input = [4725270.684, 8515734.475];
let result = bgs.transform(input, projections.BGS_1970_K3, projections.BGS_2005_KK);
// result is: 4816275.688, 332535.346
 
let input = [4816275.68, 332535.401];
let result = bgs.transform(input, projections.BGS_2005_KK, projections.BGS_1970_K3);
// result is: 4725270.677, 8515734.530
 
let input = [4613479.192, 9493233.633];
let result = bgs.transform(input, projections.BGS_1970_K5, projections.BGS_2005_KK);
// result is: 4679669.824, 569554.912
 
let input = [4679669.825, 569554.918];
let result = bgs.transform(input, projections.BGS_2005_KK, projections.BGS_1970_K5);
// result is: 4613479.193, 9493233.639
 
let input = [4708089.898, 9570974.988];
let result = bgs.transform(input, projections.BGS_1970_K7, projections.BGS_2005_KK);
// result is: 4810276.410, 626498.618
 
let input = [4810276.431, 626498.611];
let result = bgs.transform(input, projections.BGS_2005_KK, projections.BGS_1970_K7);
// result is: 4708089.919, 9570974.981
 
let input = [4547844.976, 8508858.179];
let result = bgs.transform(input, projections.BGS_1970_K9, projections.BGS_2005_KK);
// result is: 4675440.859, 330568.410
 
let input = [4675440.847, 330568.434];
let result = bgs.transform(input, projections.BGS_2005_KK, projections.BGS_1970_K9);
// result is: 4547844.965, 8508858.203

Transform points in extent

Use this method to calculate transformation parameters once and apply them to all input points.

You can either pass an extent, for which the transformation parameters will be calculated:

let extent = [4515891.16322039, 8471284.82458501, 4565579.62520789, 8551929.53794741];
let result = bgs.transformArray([...], projections.BGS_1970_K9, projections.BGS_2005_KK, true, extent);

or just pass the points and use the bounding extent:

let result = bgs.transformArray([...], projections.BGS_1970_K9, projections.BGS_2005_KK, true);

*Use TPS transformation as it gives better accuracy.

Format decimal degrees from/to degrees, minutes and seconds

import { convertDecimalDegreesToDMS, convertDMStoDecimalDegrees } from 'transformations';
 
let latitude = 42.336542;
let dms = convertDecimalDegreesToDMS(latitude);
// dms is: "422011.5512000000052"
 
let dms = '422011.5512000000052';
let result = convertDMStoDecimalDegrees(dms);
// result is: 42.336542