node-mvt-encoder

A Node.js utility to encode a vector tile spec into a Mapbox vector tile.

Installation

npm install mvt-encoder

node-gdal is a dependency of this project. It requires gdal to be installed in your environment:

apt-get update -y && apt-get install -y libproj-dev gdal-bin

Usage

var tileEncode = require('mvt-encoder');
var VectorTile = require('@mapbox/vector-tile').VectorTile

var tileSpec = [{
  name: 'blocks',
  features: [{
    geometry: "POLYGON ((0 0, 0 1, 1 1, 1 0, 0 0))",
    properties: {
      hello: "world"
    }
  }]
}];

var encoded = tileEncode(tileSpec);
var decoded = new VectorTile(encoded)

console.log(decoded.layers)
// { blocks: VectorTileLayer {...} }

Tile specification

The tileEncode function exported in this module takes one parameter: a "tile spec". This was inspired by Mapzen's mapbox-vector-tile package.

A "tile spec" is an array of "layer specs".

a "layer spec" is an object with the properties:

• name: the name of the layer (string)
• features: an array of objects with the properties:
  • geometry: a WKT representation of a feature geometry. Coordinates are relative to the tile, scaled in the range [0, 4096)
  • properties: an object with arbitrary key/values.

Notes

• Only tested for Polygon features
• Does not quantize geometry to the tile grid
• Outputs Mapbox vector tile conforming to (at best) version 1 of the spec