MVTTools

Mapnik vector tiles (MVT) reader/writer for Swift.

Installation with Swift Package Manager

dependencies: [
    .package(url: "https://github.com/Outdooractive/mvt-tools", from: "1.0.0"),
],
targets: [
    .target(name: "MyTarget", dependencies: [
        .product(name: "MVTTools", package: "mvt-tools"),
    ]),
]

Command line tool

You can install the command line tool mvt locally to /usr/local/bin with

# ./install_mvt.sh

# mvt -h
OVERVIEW: A utility for inspecting and working with vector tiles.

USAGE: mvt <subcommand>

SUBCOMMANDS:
  dump (default)          Print the vector tile as GeoJSON
  info                    Print information about the vector tile
  merge                   Merge two or more vector tiles
  query                   Query the features in a vector tile
  export                  Export the vector tile as GeoJSON
  import                  Import some GeoJSONs to a vector tile

Features

• Load and write Mapnik Vector Tiles from/to disk or data objects (also handles gzipped input)
• Export options: Zipped, buffered (in pixels or extents), simplified (in meters or extents)
• Can dump a tile as a GeoJSON object
• Supported projections: EPSG:4326, EPSG:3857 or none (uses the tile's coordinate space)
• Fast search (supports indexing), either within a bounding box or with center and radius
• Extract selected layers into a new tile
• Merge two tiles into one
• Can extract some infos from tiles like feature count, etc.
• Command line tool

Usage

Load

import MVTTools

// Load
let mvtData = Data(contentsOf: URL(fileURLWithPath: "14_8716_8015.vector.mvt"))!
let tile = VectorTile(data: mvtData, x: 8716, y: 8015, z: 14, indexed: .hilbert)!

print(tile.isIndexed)
print(tile.layerNames.sorted())

let tileAsGeoJsonData: Data? = tile.toGeoJson(prettyPrinted: true)
...

let result = tile.query(at: Coordinate3D(latitude: 3.870163, longitude: 11.518585), tolerance: 100.0)
...

Write

import MVTTools

var tile = VectorTile(x: 8716, y: 8015, z: 14)!
var feature = Feature(Point(Coordinate3D(latitude: 3.870163, longitude: 11.518585)))
feature.properties = [
    "test": 1,
    "test2": 5.567,
    "test3": [1, 2, 3],
    "test4": [
        "sub1": 1,
        "sub2": 2
    ]
]

tile.setFeatures([feature], for: "test")

// Also have a look at ``VectorTileExportOptions``
let tileData = tile.data()
...

Contributing

Please create an issue or open a pull request with a fix

Dependencies (for development)

brew install protobuf swift-protobuf swiftlint

TODOs and future improvements

• Documentation (!)

• Tests

• Decode V1 tiles

• Locking (when updating/deleting features, indexing)

• Query option: within/intersects

• https://github.com/mapbox/vtcomposite

• https://github.com/mapbox/geosimplify-js

Links

• Vector tiles

  • https://github.com/mapbox/vector-tile-spec/tree/master/2.1
  • https://github.com/mapbox/vector-tile-spec/blob/master/2.1/vector_tile.proto
  • https://docs.mapbox.com/vector-tiles/specification/#format

• Libraries

  • https://github.com/apple/swift-protobuf
  • https://github.com/Outdooractive/gis-tools

• Sample data for testing:

  • https://github.com/mapbox/mvt-fixtures
  • https://github.com/mapbox/mapnik-vector-tile/tree/master/bench
  • https://github.com/mapbox/mapnik-vector-tile/tree/master/examples
  • https://github.com/mapbox/mapnik-vector-tile/tree/master/test

• Other code for inspiration:

  • https://github.com/mapnik/node-mapnik/blob/master/src/mapnik_vector_tile.cpp
  • https://github.com/mapbox/vt2geojson

License

MIT

Author

Thomas Rasch, Outdooractive