HeatmapRenderer

AMD: require(["esri/renderers/HeatmapRenderer"], (HeatmapRenderer) => { /* code goes here */ });
ESM: import HeatmapRenderer from "@arcgis/core/renderers/HeatmapRenderer";
Class: esri/renderers/HeatmapRenderer
Inheritance: HeatmapRenderer Renderer Accessor
Since: ArcGIS API for JavaScript 4.8

The HeatmapRenderer uses kernel density to render point features in FeatureLayers, CSVLayers, GeoJSONLayers and OGCFeatureLayers as a raster surface.

To create this visual, the HeatmapRenderer fits a smoothly curved surface over each point. The surface value is highest at the location of the point and decreases proportionally to the distance from the point, reaching zero at the distance from the point specified in radius. The value of the surface equals the field value for the point, or 1 if no field is provided. The density at each pixel is calculated by adding the values of all the kernel surfaces where they overlay.

Because there isn't an API for querying density values in a layer view, we suggest you use the heatmapRendererCreator smart mapping function for creating the initial view of a heatmap, and then making renderer adjustments as needed.

Colors are assigned to each pixel based on their density value. The color ramp specified by the colorStops property maps colors to the ratio of each pixel's density value to the maxDensity. This eases the process for creating your own color stops since you don't need to know the range of density values to apply a color ramp to the renderer.

Known Limitations

Labels and filters are currently not supported in a 3D SceneView.

See also:
Example:
layer.renderer = {
  type: "heatmap",
  field: "crime_count",
  colorStops: [
    { ratio: 0, color: "rgba(255, 255, 255, 0)" },
    { ratio: 0.2, color: "rgba(255, 255, 255, 1)" },
    { ratio: 0.5, color: "rgba(255, 140, 0, 1)" },
    { ratio: 0.8, color: "rgba(255, 140, 0, 1)" },
    { ratio: 1, color: "rgba(255, 0, 0, 1)" }
  ],
  minDensity: 0,
  maxDensity: 500,
  radius: 10
};

Constructors

new HeatmapRenderer(properties)
Parameter:
properties Object
optional

See the properties for a list of all the properties that may be passed into the constructor.

Property Overview

Any properties can be set, retrieved or listened to. See the Working with Properties topic.
Show inherited properties Hide inherited properties
Name Type Summary Class
AuthoringInfomore details

Authoring metadata only included in renderers generated from one of the Smart Mapping creator methods, such as sizeRendererCreator.createContinuousRenderer() or colorRendererCreator.createContinuousRenderer().

more detailsRenderer
HeatmapColorStop[]more details

An array of objects describing the renderer's color ramp.

more detailsHeatmapRenderer
Stringmore details

The name of the class.

more detailsAccessor
Stringmore details

The name of the attribute field used to weight the density of each heatmap point.

more detailsHeatmapRenderer
Objectmore details

An object providing options for describing the renderer in the Legend.

more detailsHeatmapRenderer
Numbermore details

The max density value to be assigned a color in the heatmap surface.

more detailsHeatmapRenderer
Numbermore details

The minimum density value to be assigned a color in the heatmap surface.

more detailsHeatmapRenderer
Numbermore details

The search radius (in points) used to create a smooth kernel surface fitted around each point.

more detailsHeatmapRenderer
Numbermore details

When set, the heatmap's visualization at the given scale will remain static and not change as the user zooms in and out of the view.

more detailsHeatmapRenderer
Stringmore details

The type of renderer.

more detailsHeatmapRenderer

Property Details

Authoring metadata only included in renderers generated from one of the Smart Mapping creator methods, such as sizeRendererCreator.createContinuousRenderer() or colorRendererCreator.createContinuousRenderer(). This includes information from UI elements such as sliders and selected classification methods and themes. This allows the authoring clients to save specific overridable settings so that next time it is accessed via the UI, their selections can be remembered.

colorStops HeatmapColorStop[]

An array of objects describing the renderer's color ramp. The ratio of a pixel's density value to the maxDensity of the renderer is mapped to a corresponding color. The color of the first stop (i.e. the stop with the lowest ratio value) must have an alpha value of 0 for the underlying basemap to be visible in the app.

The default value is the following:

[
  { ratio: 0, color: "rgba(255, 140, 0, 0)" },
  { ratio: 0.75, color: "rgba(255, 140, 0, 1)" },
  { ratio: 0.9, color: "rgba(255, 0,   0, 1)" }
]
declaredClass Stringreadonly inherited

The name of the class. The declared class name is formatted as esri.folder.className.

field String

The name of the attribute field used to weight the density of each heatmap point.

For example, suppose you have a layer of points representing buildings containing a field num_units for the number of units in the building (if it's an apartment complex). You could weight the heatmap renderer based on the num_units field to create a heatmap representing the density of housing units in a city.

Example:
renderer.field = "num_units";
legendOptions Object
Since: ArcGIS API for JavaScript 4.24

An object providing options for describing the renderer in the Legend.

Properties:
minLabel String
optional

The label used to describe low density areas in the legend. If not specified, then a localized version of "Low" will display in the legend.

maxLabel String
optional

The label used to describe max density areas in the legend. If not specified, then a localized version of "High" will display in the legend.

title String
optional

Describes the variable driving the visualization. This is displayed as the title of the corresponding renderer in the Legend and takes precedence over a field alias.

Example:
renderer.legendOptions = {
  title: "Car crashes",
  minLabel: "Few crashes",
  maxLabel: "Frequent crashes"
};
maxDensity Number
Since: ArcGIS API for JavaScript 4.24

The max density value to be assigned a color in the heatmap surface. Both minDensity and maxDensity determine how colorStops are applied to the heatmap surface. Pixels with density values above this number will be assigned the final (or hottest) color in the color ramp.

Typically, minDensity will be zero and maxDensity will be set to a higher value appropriate for the dataset. The default may not be ideal for your dataset, so this value will likely need to change.

Determining the best values for minDensity and maxDensity is an exercise left up to the developer since different types, scales, densities, and distributions of data will require different values for these properties to create a visually pleasing separation of high and low density areas appropriate for the data and the application.

Because there isn't an API for querying density values in a layer view, we suggest you use the heatmapRendererCreator smart mapping function for creating the initial view of a heatmap, and then making adjustments as needed.

Default Value:0.04
Example:
renderer.maxDensity = 100;
minDensity Number
Since: ArcGIS API for JavaScript 4.24

The minimum density value to be assigned a color in the heatmap surface. Both minDensity and maxDensity determine how colorStops are applied to the heatmap surface. Pixels with density values below the minDensity will be excluded from the visualization.

When using a field to weight the heatmap, setting minDensity above zero might help to visually deemphasize frequently occurring but low value areas. This property does not actually filter the data or modify the calculated density value. Rather, it scales the color ramp such that a higher density value is required for a pixel to get a noticeable color.

Determining the best values for minDensity and maxDensity is an exercise left up to the developer since different types, scales, densities, and distributions of data will require different values for these properties to create a visually pleasing separation of high and low density areas appropriate for the data and the application.

Because there isn't an API for querying density values in a layer view, we suggest you use the heatmapRendererCreator smart mapping function for creating the initial view of a heatmap, and then making adjustments as needed.

Default Value:0
Example:
renderer.minDensity = 10;
Autocasts from String|Number
Since: ArcGIS API for JavaScript 4.24

The search radius (in points) used to create a smooth kernel surface fitted around each point. The density value is highest at the location of the point and decreases as the distance away from the point increases. The density value is 0 at the distance specified in radius from the point.

Known Limitations

Default Value:18
Examples:
// radius in points
renderer.radius = 14;
// radius in pixels
renderer.radius = "20px";
// radius in points
renderer.radius = "14pt";
referenceScale Number
Since: ArcGIS API for JavaScript 4.24

When set, the heatmap's visualization at the given scale will remain static and not change as the user zooms in and out of the view. This fixes each point's influence radius to a real-world range that doesn't change depending on the zoom level). The pixels of radius are defined at the reference scale.

A value of 0 means that the heatmap does not have a referenceScale.

The following images demonstrate how setting a reference scale will preserve a heatmap across various scales as opposed to dynamically updating on zoom.

Zoom offset from reference scale Static (reference scale) Dynamic (no reference scale)
+1 LOD static-in1 dynamic-in1
reference scale static-out1 dynamic-out1
-1 LOD static-out1 dynamic-out1
Default Value:0
See also:
Example:
// locks the heatmap surface at the current view scale
// so that it doesn't change as the user zooms in and out
renderer.referenceScale = view.scale;
type Stringreadonly

The type of renderer.

For HeatmapRenderer the type is always "heatmap".

Method Overview

Show inherited methods Hide inherited methods
Name Return Type Summary Class
HeatmapRenderermore details

Creates a deep clone of the renderer.

more detailsHeatmapRenderer
*more details

Creates a new instance of this class and initializes it with values from a JSON object generated from an ArcGIS product.

more detailsRenderer
Objectmore details

Converts an instance of this class to its ArcGIS portal JSON representation.

more detailsRenderer

Method Details

clone(){HeatmapRenderer}

Creates a deep clone of the renderer.

Returns:
Type Description
HeatmapRenderer A deep clone of the object that invoked this method.
Example:
// Creates a deep clone of the first layer's renderer
let renderer = view.map.layers.getItemAt(0).renderer.clone();
fromJSON(json){*}static

Creates a new instance of this class and initializes it with values from a JSON object generated from an ArcGIS product. The object passed into the input json parameter often comes from a response to a query operation in the REST API or a toJSON() method from another ArcGIS product. See the Using fromJSON() topic in the Guide for details and examples of when and how to use this function.

Parameter:
json Object

A JSON representation of the instance in the ArcGIS format. See the ArcGIS REST API documentation for examples of the structure of various input JSON objects.

Returns:
Type Description
* Returns a new instance of this class.
toJSON(){Object}inherited

Converts an instance of this class to its ArcGIS portal JSON representation. See the Using fromJSON() guide topic for more information.

Returns:
Type Description
Object The ArcGIS portal JSON representation of an instance of this class.

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