@mapbox/geojson-rewind

What is @mapbox/geojson-rewind?

@mapbox/geojson-rewind is an npm package that allows you to reorient the winding order of GeoJSON polygons to ensure they follow the right-hand rule. This is useful for ensuring compatibility with various GIS systems and tools that expect polygons to be wound in a specific direction.

What are @mapbox/geojson-rewind's main functionalities?

Rewind GeoJSON Polygons

This feature allows you to reorient the winding order of GeoJSON polygons. The `rewind` function takes a GeoJSON object and a boolean indicating whether to reverse the winding order to follow the right-hand rule. The code sample demonstrates how to use the package to rewind a GeoJSON polygon.

const rewind = require('@mapbox/geojson-rewind');
const geojson = {
  "type": "FeatureCollection",
  "features": [
    {
      "type": "Feature",
      "geometry": {
        "type": "Polygon",
        "coordinates": [
          [
            [-101.744384765625, 39.32155002466662],
            [-101.5521240234375, 39.330048552942415],
            [-101.40380859375, 39.330048552942415],
            [-101.33239746093749, 39.364032338047984],
            [-101.041259765625, 39.36827914916011],
            [-100.975341796875, 39.30454987014581],
            [-101.0399169921875, 39.24501680713314],
            [-101.24389648437499, 39.16414104768742],
            [-101.54541015625, 39.178362282029745],
            [-101.744384765625, 39.32155002466662]
          ]
        ]
      }
    }
  ]
};
const rewindedGeojson = rewind(geojson, true);
console.log(JSON.stringify(rewindedGeojson, null, 2));

Other packages similar to @mapbox/geojson-rewind

geojson-rewind

The `geojson-rewind` package provides similar functionality to @mapbox/geojson-rewind by reorienting the winding order of GeoJSON polygons. It is a lightweight alternative and can be used in similar scenarios where ensuring the correct winding order is necessary.

README

geojson-rewind

The GeoJSON specification is picky about winding order.

This helps you generate compliant Polygon and MultiPolygon geometries. Furthermore it lets you use Canvas and other drawing libraries's default behavior to color the interior rings of Polygon and MultiPolygon features.

Usage

As NPM module:

npm install --save @mapbox/geojson-rewind

As a console utility:

# install
npm install -g @mapbox/geojson-rewind
# use
geojson-rewind foo.geojson

As a browser library: geojson-rewind.js

API

rewind(geojson, clockwise)

Given a GeoJSON FeatureCollection, Feature, or Geometry, return a version with inner and outer rings of different winding orders.

If clockwise is true, the outer ring is clockwise, otherwise it is counterclockwise.