wkt-to-gml 📍➡️🗺️

A lightweight TypeScript library for converting Well-Known Text (WKT) to Geography Markup Language (GML). Supports all standard geometry types with customizable output.

Features

✅ Supports all standard WKT geometries:

• Point, LineString, Polygon
• MultiPoint, MultiLineString, MultiPolygon
• GeometryCollection

✅ Customizable GML output:

• Choose your GML namespace (default: 3.2).
• Toggle pretty-printing and XML declaration.

✅ TypeScript & JavaScript: Fully typed for seamless integration.

Installation

npm install wkt-to-gml

or

yarn add wkt-to-gml

or

pnpm add wkt-to-gml

Usage

Basic Conversion

import { wktToGml } from 'wkt-to-gml';

const gml = wktToGml('POINT(30 10)');
console.log(gml);

Output:

<gml:Point xmlns:gml="http://www.opengis.net/gml/3.2">
  <gml:pos>30 10</gml:pos>
</gml:Point>

Advanced Options

const gml = wktToGml('LINESTRING(10 20, 30 40)', {
  gmlNamespace: 'http://www.opengis.net/gml/3.3', // Custom namespace
  prettyPrint: false, // Minified output
  headlessXml: true,  // Omit <?xml?>
});

Output:

<gml:LineString xmlns:gml="http://www.opengis.net/gml/3.3"><gml:posList>10 20 30 40</gml:posList></gml:LineString>

API

wktToGml(wktString: string, options?: WktToGmlOptions): string

Options

| Key | Type | Default | Description |
|-----------------|-----------|----------------------------------|-------------|
| gmlNamespace | string | "http://www.opengis.net/gml/3.2" | Custom GML namespace URI. |
| prettyPrint | boolean | true | Pretty-print XML with indentation. |
| headlessXml | boolean | true | Omit <?xml version="1.0"?>. |

Examples

1. Convert a Polygon

wktToGml('POLYGON((30 10, 40 40, 20 40, 10 20, 30 10))');

Output:

<gml:Polygon xmlns:gml="http://www.opengis.net/gml/3.2">
  <gml:exterior>
    <gml:LinearRing>
      <gml:posList>30 10 40 40 20 40 10 20 30 10</gml:posList>
    </gml:LinearRing>
  </gml:exterior>
</gml:Polygon>

2. Convert a MultiLineString (Minified)

wktToGml('MULTILINESTRING((10 10, 20 20), (30 30, 40 40))', { prettyPrint: false });

Output:

<gml:MultiLineString xmlns:gml="http://www.opengis.net/gml/3.2"><gml:lineStringMember><gml:LineString><gml:posList>10 10 20 20</gml:posList></gml:LineString></gml:lineStringMember><gml:lineStringMember><gml:LineString><gml:posList>30 30 40 40</gml:posList></gml:LineString></gml:lineStringMember></gml:MultiLineString>

Contributing

PRs welcome! Run tests with:

npm test

License

MIT © Bartłomiej Strama 2025