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Layer types

cartokit ships with a compact core of common cartographic forms, with support for transitioning between forms without transforming your data.

As a tool for interactive cartography, cartokit adopts the language of cartographers to describe layers on your map. Rather than focusing on the appearance of individual marks, cartokit gives each layer a type that corresponds to a particular cartographic form. A layer’s type determines not only which of its visual attributes can be styled, but also how data is mapped to particular attributes for display.

Layer types

Section titled “Layer types”

cartokit currently supports six layer types. The available layer types for a given layer are dependent on the geometry of the input data.

Point

Section titled “Point”

The Point layer type displays all features of a layer as points with a consistent, configurable radius. This type is the default type for Point and MultiPoint GeoJSON datasets.

A Point layer in cartokit consisting of earthquakes from the USGS real-time earthquake feed.

Proportional Symbol

Section titled “Proportional Symbol”

The Proportional Symbol layer type allows scaling of point symbols based on the value of a selected attribute for each data point. This is one option type for MultiPoint and MultiPolygon GeoJSON datasets.

A Proportional Symbol layer in cartokit consisting of all natural gas-powered electricity plants in the United States and their capacities.

Heatmap

Section titled “Heatmap”

The Heatmap layer type displays the density of data using a color gradient with intensity styled by a Constant concentration of points or weighted Range with selected attribute value. This is one option type for MultiPoint GeoJSON datasets.

A Heatmap Symbol layer in cartokit of concentration of gas-powered electricity plants capacities in the United States.

Polygon

Section titled “Polygon”

The Polygon layer type displays geographic areas as filled shapes with configurable fill color and border style. This type is the default type for Polygon and MultiPolygon GeoJSON datasets.

A Proportional Symbol layer in cartokit displaying urban areas in the United States.

Choropleth

Section titled “Choropleth”

The Choropleth layer type colors polygons based on the value of a selected attribute, either Categories or a numerical Range with a using a configurable scale. This is one option type for MultiPolygon GeoJSON datasets.

A Choropleth Symbol layer in cartokit visualizing the predicted change in deaths linked to temperature by 2080 across the world.

Dot Density

Section titled “Dot Density”

The Dot Density layer type distributes points within polygon boundaries, with the number of points proportional to a selected attribute value. This is one option type for MultiPolygon GeoJSON datasets.

A Dot Density Symbol layer in cartokit visualizing the predicted change in deaths linked to temperature by 2080 across the world.

Supported Input Geometries

Section titled “Supported Input Geometries”
  • Point
  • MultiPoint
  • LineString (uses centroid)
  • MultiLineString (uses centroid)
  • Polygon (uses centroid)
  • MultiPolygon (uses centroid)