VisualVariablesMixin

An array of VisualVariable objects. Each object must indicate the type of visual variable to apply (e.g. ColorVisualVariable, SizeVisualVariable, OpacityVisualVariable, RotationVisualVariable), the numeric field or expression from which to drive the visualization, and the visual values to map to the data. The following list identifies each visual variable type and provides a link to the specification table of each.

Type	Object Specification	Legend Example
color	ColorVisualVariable
size	SizeVisualVariable
opacity	OpacityVisualVariable
rotation	RotationVisualVariable	-

Visual variables are primarily be used in two ways.

1. Thematic mapping

In most cases, visual variables are used to create visualizations based on a thematic attribute (e.g. population, education, rank, money, magnitude, etc.) in either 2D or 3D.

renderer.visualVariables = [{
  type: "size",
  field: "POP_POVERTY",
  normalizationField: "TOTPOP_CY",
  legendOptions: {
    title: "% population in poverty by county"
  },
  stops: [
    { value: 0.15, size: 4, label: "<15%" },
    { value: 0.25, size: 12, label: "25%" },
    { value: 0.35, size: 24, label: ">35%" }
  ]
}];

You can take the visualization a step further and use multiple visual variables in the same renderer. The sample below uses three visual variables (size, color, and opacity).

2. Mapping real-world sizes

The size visual variable can be used to visualize the true sizes of features (e.g. tree canopy, road width, building height, etc.) based on their size in the real world. This can be particularly powerful when working in a 3D SceneView. The image below shows a layer of trees that uses visual variables to size each feature to the true dimensions of each tree based on data stored in multiple attribute fields.

See the Thematic visualization with realistic 3D symbols for an example of using multiple visual variables to visualize your data.

See also

• Styles and data visualization