ol-heatmap-layer

ol-heatmap-layer can render vector data as a heatmap from various backend services. It should be used with together with ol-source-vector component.

Usage

Example below shows how you can use ol-heatmap-layer and ol-source-vector to render a heatmap from a backend source.

HeatmapLayerDemo.vue

<template>
  <ol-map
    ref="map"
    :loadTilesWhileAnimating="true"
    :loadTilesWhileInteracting="true"
    style="height: 400px"
  >
    <ol-view
      ref="view"
      :center="center"
      :zoom="zoom"
      :projection="projection"
    />

    <ol-tile-layer>
      <ol-source-osm />
    </ol-tile-layer>

    <ol-heatmap-layer
      title="heatmap"
      :blur="20"
      :radius="20"
      :weight="heatmapWeight"
      :zIndex="1"
    >
      <ol-source-vector
        ref="earthquakes"
        url="https://raw.githubusercontent.com/openlayers/openlayers/main/examples/data/kml/2012_Earthquakes_Mag5.kml"
        :format="kml"
      >
      </ol-source-vector>
    </ol-heatmap-layer>
  </ol-map>
</template>

<script setup>
import { ref, inject } from "vue";

const center = ref([101.97, 4.21]);
const projection = ref("EPSG:4326");
const zoom = ref(5);
const format = inject("ol-format");
const kml = new format.KML({ extractStyles: false });
const heatmapWeight = function (feature) {
  // 2012_Earthquakes_Mag5.kml stores the magnitude of each earthquake in a
  // standards-violating <magnitude> tag in each Placemark.  We extract it from
  // the Placemark's name instead.
  const name = feature.get("name");
  const magnitude = parseFloat(name.substr(2));
  return magnitude - 5;
};
</script>

Properties

weight

• Type: String | Function
• Default: 'weight'

The feature attribute to use for the weight or a function that returns a weight from a feature. Weight values should range from 0 to 1 (and values outside will be clamped to that range).

extent

• Type: Array

The bounding extent for layer rendering. The layer will not be rendered outside of this extent.

blur

• Type: Number
• Default: 15

The blur size in pixels.

radius

• Type: Number

The radius size in pixels.