What are the steps to dynamically overlay a raster image on Leaflet maps?

Utilizing latitude and longitude coordinates provided by the user, I am creating a map using leaflet.js while also calculating a heatmap in the background, such as a population density map within a 5km radius of the chosen coordinates.

I am looking to overlay the generated heatmap onto my map. Currently, I have an HTML file for mapping and a JavaScript file for storing the selected coordinates, interest polygons, and hopefully the raster map for that area.

<!DOCTYPE html>
<html>
<head>
  <title>Testmap</title>
  <script src="http://d3js.org/d3.v3.min.js"></script>
  <script src="http://d3js.org/topojson.v1.min.js"></script>
  <style>
    @import url(http://cdn.leafletjs.com/leaflet-0.6.1/leaflet.css);
    #overlay{
      fill:None;
      stroke:#ff00ff;
      stroke-width:4px;
    }
  </style>
</head>
<body>
  <div id="map" style="width: 960px; height: 600px"></div>
  <script src="http://cdn.leafletjs.com/leaflet-0.6.1/leaflet.js"
  </script>
  <script src="rois.js"></script>
  <script>
  var toolserver = L.tileLayer('http://{s}.www.toolserver.org/tiles/bw-mapnik/{z}/{x}/{y}.png');
  var stamen = L.tileLayer('http://{s}.tile.stamen.com/toner/{z}/{x}/{y}.png', {attribution: 'myMap'}).addTo(map);
  var baseLayers = {"stamen": stamen, "toolserver-mapnik":toolserver};

  var geojson = L.geoJson(rois, {
      onEachFeature: onEachFeature
  }).addTo(map)

  var overlays = {
      "geoJson": geojson
  };

  function onEachFeature(feature, layer){
    if (feature.properties) {
      layer.bindPopup("<b>" + feature.properties.street + "</b> is " + feature.properties.length + "km long.");
    }
  }

  var svgContainer= d3.select(map.getPanes().overlayPane).append("svg");
  var group= svgContainer.append("g").attr("class", "leaflet-zoom-hide");
  var path = d3.geo.path().projection(project);
  function project(point) {
    var latlng = new L.LatLng(point[1], point[0]);
    var layerPoint = map.latLngToLayerPoint(latlng);
    return [layerPoint.x, layerPoint.y];
  }  

  </script>
 </body>
</html>

The rois.js file is dynamic and includes selected coordinates and polygons to be displayed on the map. I want to learn how to incorporate raster information into this setup.

var map = L.map('map').setView([52.500,13.385], 13);
var rois = [{
  "type": "FeatureCollection",                                                                        
  "features": [{
    "type": "Feature",
    "id": 1, 
    "geometry": {
      "type": "Polygon",
      "coordinates": [[[13.370, 52.491], [13.400, 52.491], [13.400, 52.509],[13.370, 52.509],[13.370, 52.491]]]
    }
  },
  { "type": "Feature",
    "id": 2, 
    "geometry": {
      "type": "Polygon",
      "coordinates": [[[13.415, 52.496], [13.425, 52.505], [13.435, 52.496], [13.415, 52.496]]]
    }
  }]
}];

Thank you, FP

Answer №1

To find out more about creating heatmaps using Leaflet, check out the Leaflet plugins for generating heatmaps. It's also recommended to update your Leaflet version since 0.6.x is outdated by over three years.

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