leaflet-shadow-simulator

Using Mapbox GL JS/Maplibre GL JS? Try mapbox-gl-shadow-simulator

Shadow simulator for Leaflet. Visualize sunlight and shadow on a map for any date and time of year.

Live Demo

Download

unpkg CDN

Installation

In a browser:

<script src="https://unpkg.com/leaflet-shadow-simulator/dist/leaflet-shadow-simulator.umd.min.js"></script>

Using npm:

npm i leaflet-shadow-simulator --save

Usage

In a browser:

<link rel="stylesheet" href="https://unpkg.com/[email protected]/dist/leaflet.css" />
<script src="https://unpkg.com/[email protected]/dist/leaflet.js"></script>
<script src="https://unpkg.com/leaflet-shadow-simulator/dist/leaflet-shadow-simulator.umd.min.js"></script>
<script>
  var map = L.map("mapid"); 

  const shadeMap = L.shadeMap({
    date: new Date(),    // display shadows for current date
    color: '#01112f',    // shade color
    opacity: 0.7,        // opacity of shade color
    apiKey: "XXXXXX",    // obtain from https://shademap.app/about/
    terrainSource: {
      tileSize: 256,       // DEM tile size
      maxZoom: 15,         // Maximum zoom of DEM tile set
      getSourceUrl: ({ x, y, z }) => {
        // return DEM tile url for given x,y,z coordinates
        return `https://s3.amazonaws.com/elevation-tiles-prod/terrarium/${z}/${x}/${y}.png`
      },
      getElevation: ({ r, g, b, a }) => {
        // return elevation in meters for a given DEM tile pixel
        return (r * 256 + g + b / 256) - 32768
      }
    },
  }).addTo(map);

  // advance shade by 1 hour
  shadeMap.setDate(new Date(Date.now() + 1000 * 60 * 60)); 

  // sometime later...
  // ...remove layer
  shadeMap.remove();
</script>

Using Node.js:

import * as L from 'leaflet'
import ShadeMap from 'leaflet-shadow-simulator';

const map = L.map("mapid"); 

const shadeMap = new ShadeMap({
  date: new Date(),    // display shadows for current date
  color: '#01112f',    // shade color
  opacity: 0.7,        // opacity of shade color
  apiKey: "XXXXXX",    // obtain from https://shademap.app/about/
  terrainSource: {
    tileSize: 256,       // DEM tile size
    maxZoom: 15,         // Maximum zoom of DEM tile set
    getSourceUrl: ({ x, y, z }) => {
      // return DEM tile url for given x,y,z coordinates
      return `https://s3.amazonaws.com/elevation-tiles-prod/terrarium/${z}/${x}/${y}.png`
    },
    getElevation: ({ r, g, b, a }) => {
      // return elevation in meters for a given DEM tile pixel
      return (r * 256 + g + b / 256) - 32768
    }
  },
}).addTo(map);

// advance shade by 1 hour
shadeMap.setDate(new Date(Date.now() + 1000 * 60 * 60)); 

// sometime later
// ...remove layer
shadeMap.remove();

Constructor options

Property name | Type | Default value | Comment :--- | :--- | :--- | :--- apiKey | String | '' | See https://shademap.app/about/ date | Date | new Date() | Sun's position in the sky is based on this date color | String | #000 | 3 or 6 digit hexadecimal number opacity | Number | 0.3 sunExposure | Object | See sunExposure | Display sun exposure for provided date range terrainSource | Object | See terrainSource | Specify DEM or DSM tiles containing terrain elevation data getFeatures | Function | See getFeatures | Returns GeoJSON of objects, such as buildings, to display on the map

terrainSource

An object describing a DEM tile set to use for terrain shadows

Property name | Type | Default value | Comment :--- | :--- | :--- | :--- maxZoom | Number | 15 | Max zoom for custom DEM tile source tileSize | Number | 256 | Tile size for custom DEM tile source sourceUrl | Function | Returns tile encoding 0m elevation for all locations | Returns url of DEM tile for given (x, y, z) coordinate getElevation | Function | return (r * 256 + g + b / 256) - 32768 | Returns elevation in meters for each (r,g,b,a) pixel of DEM tile

sunExposure

An object describing sun exposure settings Property name | Type | Default value | Comment :--- | :--- | :--- | :--- enabled | Boolean | false | Should sun exposure be displayed startDate | Date | new Date() | Start date of sun exposure time interval endDate | Date | new Date() | End date of sun exposure time interval iterations | number | 32 | Number of discrete chunks to calculate shadows for between startDate and endDate. A larger number will provide more detail but take longer to compute.

Open Data on AWS for terrainSource

A global dataset providing bare-earth terrain heights, tiled for easy usage and provided on S3 - More info

{
  tileSize: 256,
  maxZoom: 15,
  getSourceUrl: ({x, y, z}) => {
    return `https://s3.amazonaws.com/elevation-tiles-prod/terrarium/${z}/${x}/${y}.png`;
  },
  getElevation: ({r, g, b, a}) => {
    return (r * 256 + g + b / 256) - 32768;
  }
}

Mapbox Terrain DEM V1 for terrainSource

Mapbox Terrain-DEM v1 is a Mapbox-provided raster tileset is a global elevation layer. This tileset contains raw height values in meters in the Red, Green, and Blue channels of PNG tiles that can be decoded to raw heights in meters - More info

{
  tileSize: 514,
  maxZoom: 14,
  getSourceUrl: ({x, y, z}) => {
    const subdomain = ['a', 'b', 'c', 'd'][(x + y) % 4];
    return `https://${subdomain}.tiles.mapbox.com/raster/v1/mapbox.mapbox-terrain-dem-v1/${z}/${x}/${y}.webp?sku=101wuwGrczDtH&access_token=${MAPBOX_API_KEY}`;
  },
  getElevation: ({r, g, b, a}) => {
    return -10000 + ((r * 256 * 256 + g * 256 + b) * .1);
  }
}

Maptiler Terrain RGB v2

More info

{
  tileSize: 514,
  maxZoom: 12,
  getSourceUrl: ({x, y, z}) => {
    return `https://api.maptiler.com/tiles/terrain-rgb-v2/${z}/${x}/${y}.webp?key=${MAPTILER_KEY}`;
  },
  getElevation: ({r, g, b, a}) => {
    return -10000 + ((r * 256 * 256 + g * 256 + b) * .1);
  }
}

getFeatures

Returns a GeoJSON collection of features whose shadows will be displayed on the map. Currently only supports Polygon and MultiPolygon.

Adds a 1000 meter tall structure near Alexandria, Egypt

getFeatures: () => {
  return [{
    "type": "Feature",
    "geometry": {
      "type": "Polygon",
      "coordinates": [
        [29.8148007, 31.2240349],
        [29.8248007, 31.2240349],
        [29.8248007, 31.2140349],
        [29.8148007, 31.2140349],
      ]
    },
    "properties": {
      "height": 1000,
      "render_height": 1000,
      "name": "Alexandria column"
    }
  },
},

Using overpass turbo to load buildings

getFeatures: async () => {
  if (map.getZoom() > 15) {
    const bounds = map.getBounds();
    const north = bounds.getNorth();
    const south = bounds.getSouth();
    const east = bounds.getEast();
    const west = bounds.getWest();
    const query = `https://overpass-api.de/api/interpreter?data=%2F*%0AThis%20has%20been%20generated%20by%20the%20overpass-turbo%20wizard.%0AThe%20original%20search%20was%3A%0A%E2%80%9Cbuilding%E2%80%9D%0A*%2F%0A%5Bout%3Ajson%5D%5Btimeout%3A25%5D%3B%0A%2F%2F%20gather%20results%0A%28%0A%20%20%2F%2F%20query%20part%20for%3A%20%E2%80%9Cbuilding%E2%80%9D%0A%20%20way%5B%22building%22%5D%28${south}%2C${west}%2C${north}%2C${east}%29%3B%0A%29%3B%0A%2F%2F%20print%20results%0Aout%20body%3B%0A%3E%3B%0Aout%20skel%20qt%3B`;
    const response = await fetch(query)
    const json = await response.json();
    const geojson = osmtogeojson(json);
    // If no building height, default to one storey of 3 meters
    geojson.features.forEach(feature => {
      if (!feature.properties) {
        feature.properties = {};
      }
      if (!feature.properties.height) {
        feature.properties.height = 3;
      }
    });
    return geojson.features;
  }
  return [];
},

Available functions

setDate(date: Date) - update shade layer to reflect new date

setColor(color: String) - change shade color

setOpacity(opacity: Number) - change shade opacity

setSunExposure(enabled: Boolean, options: SunExposureOptions) - toggle between shadows and sun exposure mode

getHoursOfSun(x: Number, y: Number) - if sun exposure mode enabled, returns the hours of sunlight for a given pixel on the map

remove() - remove the layer from the map