> For the complete documentation index, see [llms.txt](https://developers.felt.com/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://developers.felt.com/felt-style-language/types-of-visualizations/heatmaps.md).

# Heatmaps

Heatmaps are used to visualize the density of points on a map.

Heatmaps work on point layers only, and show concentration rather than individual feature values — if you need to read a specific attribute, use a [numeric](/felt-style-language/types-of-visualizations/numeric-visualizations-color-and-size.md) visualization instead. The `config` block must be empty (`{}`), and heatmaps support no popups or labels.

Heatmap visualizations are defined using `"type": "heatmap"` and allow the following properties to be set:

| Field name  | Type   | Default | Typical range | Description                                                                                                                                                                                                                  |
| ----------- | ------ | ------- | ------------- | ---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
| `color`     | string | none    | —             | A [heatmap palette](/felt-style-language/colors-and-palettes.md#heatmap-palettes) name, from less density to more. Always set it: without one, the heatmap renders in a single solid color (`#EE4D5A`) with no density ramp. |
| `size`      | number | 10      | 1–30 px       | Radius of influence in pixels. Larger = smoother, smaller = more detailed.                                                                                                                                                   |
| `intensity` | number | 0.5     | 0.1–3.0       | How quickly density saturates. Higher = more contrast.                                                                                                                                                                       |
| `opacity`   | number | 0.9     | 0–1           | Transparency.                                                                                                                                                                                                                |

Tune `size` for the zoom you expect to view at — larger at low zoom, smaller at high zoom.

This is an example of a heatmap visualization

![](https://293097899-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2FLlIfNdbm4rCsu755xrdc%2Fuploads%2FaRBR1UIxnfla7giu9ECB%2FScreenshot%202023-08-09%20at%2015.51.42.png?alt=media\&token=94ca4e45-93cd-4946-9d5e-5eb6954cf529)

defined with the following visualization

```json
{
  "version": "2.3.1",
  "type": "heatmap",
  "config": {},
  "legend": {"displayName": {"0": "Low", "1": "High"}},
  "paint": {"color": "@purpYlPink", "size": 10, "intensity": 0.2}
}
```


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