heatmap | API Reference | ArcGIS Maps SDK for JavaScript 4.31

See also

Method Overview

Name	Return Type	Summary	Object
	Promise<HeatmapRendererResult>	Generates a HeatmapRenderer that may be applied directly to the layer used to call this method.	heatmap
	HeatmapRenderer	Allows you to update the colorStops of a HeatmapRenderer with opacity, making the low density areas of the heat map to fade out.	heatmap

Method Details

createRenderer Method createRenderer(params){Promise<HeatmapRendererResult>}

Generates a HeatmapRenderer that may be applied directly to the layer used to call this method. The renderer represents points as a continuous surface using optimal colors for the view's background.

This method should be called when at least some points are visible in the input view's extent. If no points are visible in the view, then the response will not return a useful visualization.

In most cases you will provide a layer, view, and optional field to generate this renderer. This is a scenario in which the statistics and the distribution of the data aren't well known and the user doesn't know what colors to use in the visualization.

The other options are provided for convenience for more involved custom visualization authoring applications. For example, if you already generated statistics in another operation, you can pass the statistics object to the statistics parameter to avoid making an extra call to the server.

Parameters

Specification

params Object

Input parameters for generating a heatmap visualization based on data returned from a given field. See the table below for details of each parameter.

Specification

The point layer for which the visualization is generated.

view MapView|SceneView

The view instance in which the visualization will be rendered.

field String

optional

The name of the field whose data will be queried for statistics and used for the basis of the data-driven visualization. The value of the field is used as a multiplier in the heatmap, making areas with high field values hotter than areas where the features have low field values.

heatmapScheme HeatmapScheme

optional

In authoring apps, the user may select a pre-defined heatmap scheme. Pass the scheme object to this property to avoid getting one based on the view's background.

statistics HeatmapStatisticsResult

optional

A statistics object generated from the heatmapStatistics function. If statistics for the field have already been generated, then pass the object here to avoid making a second statistics query to the server.

fadeRatio Number

optional

Default Value: 0.2

Indicates how much to fade the lower color stops with transparency to create a fuzzy boundary on the edge of the heatmap. A value of 0 makes a discrete boundary on the lower color stop.

fadeToTransparent Boolean

optional

Default Value: true

Indicates whether the heatmap should fade its colors to transparent. When false, the fadeRatio parameter is ignored.

radius Number

optional

Default Value: 18

The radius in points that determines the area of influence of each point. A higher radius indicates points have more influence on surrounding points.

minRatio Number

optional

Default Value: 0.01

The minimum ratio used in the HeatmapRenderer.colorStops of the output renderer.

maxRatio Number

optional

Default Value: 1

The maximum ratio used in the HeatmapRenderer.colorStops of the output renderer.

filter FeatureFilter

optional

Since 4.31 When defined, only features included in the filter are considered in the attribute and spatial statistics calculations when determining the final renderer. This is useful when a lot of variation exists in the data that could result in undesired data ranges. A common use case would be to set a filter that only includes features in the current extent of the view where the data is most likely to be viewed. Currently, only geometry filters with an intersects spatial relationship are supported. All other filter types (including where) are ignored.

signal AbortSignal

optional

Allows for cancelable requests. If canceled, the promise will be rejected with an error named AbortError. See also AbortController.

Returns

Type	Description
Promise<HeatmapRendererResult>	Resolves to an instance of HeatmapRendererResult.

Example

let earthquakeLayer = new FeatureLayer({
  // url to a point dataset
});

// visualization based on field

let heatmapParams = {
  layer: earthquakeLayer,
  view: view,
  field: "magnitude"
};

// when the promise resolves, apply the renderer to the layer
heatmapRendererCreator.createRenderer(heatmapParams)
  .then(function(response){
    earthquakeLayer.renderer = response.renderer;
  });

updateRenderer Method updateRenderer(params){HeatmapRenderer} Since: ArcGIS Maps SDK for JavaScript 4.25 heatmap since 4.11, updateRenderer added at 4.25.

Allows you to update the colorStops of a HeatmapRenderer with opacity, making the low density areas of the heat map to fade out.

Parameters

Specification

params Object

Input parameters for updating a heatmap renderer with a given fadeRatio.

Specification

renderer HeatmapRenderer

The heatmap renderer for which to add or remove opacity.

fadeRatio Number

optional

Indicates how much to fade the lower color stops with transparency to create a fuzzy boundary on the edge of the heatmap. A value of 0 makes a discrete boundary on the lower color stop.

Returns

Type	Description
HeatmapRenderer	The updated HeatmapRenderer.

Example

const renderer = heatmapRendererCreator.updateRenderer({
  renderer: layer.renderer
  fadeRatio: 0.7
});
layer.renderer = renderer;

Type Definitions

HeatmapRendererResult Type Definition HeatmapRendererResult

The result object of the createRenderer() method. See the table below for details of each property.

Properties: renderer HeatmapRenderer

The renderer object configured to best match the view's background and the spread of the data. Set this on a layer's renderer property to update its visualization.

scheme HeatmapScheme

The color scheme used by the renderer.

defaultValuesUsed Boolean

Indicates whether default values are used in the absence of sufficient data and/or statistics from the layer. Default values are typically used when all features have the same field value or no value at all.

statistics HeatmapStatisticsResult

Basic statistics required for generating a renderer with optimal values for the given layer and view.

basemapId String

The ID of the basemap used to determine the optimal color stops of the heatmap.

basemapTheme String

Indicates whether the average color of the input view's basemap is light or dark.