Flow Layer

The Flow Layer is an effective way of visualizing origin-destination movement patterns. Flows are a great choice for analyzing traffic flows, commute patterns, and migrations.

An example of a Flow Layer.An example of a Flow Layer.

An example of a Flow Layer.

Create a Flow Layer

To create a Flow Layer, create a new layer, then select Flow Layer.

The following columns are used to create a Flow layer:

ColumnTypeDescription
Source LatnumberRequired. The latitude of source/origin points.
Source LngnumberRequired. The longitude of source/origin points.
Target LatnumberRequired. The latitude of target/destination points.
Target LngnumberRequired. The longitude of target/destination points.
CountnumberA count of trips between source/target pairs. Count is the weight value for all flows.
If not defined, each row containing a source/target pair is counted as one trip.
Source NamestringThe name/label for source points. Appears in tooltips and cluster names.
If not defined, the latitude and longitude of the source points are used.
Target NamestringThe name/label for target points. Appears in tooltips and cluster names.
If not defined, the latitude and longitude of the target points are used.

Creation with H3 Data

The Flow Layer also supports H3 data for source/target locations.

ColumnTypeDescription
Source H3numberRequired. The H3 indexes of source/origin points.
Target H3numberRequired. The h3 indexes of target/destination points.
CountnumberA count of trips between source/target pairs. Count is the weight value for all flows.
If not defined, each row containing a source/target pair is counted as one trip.
Source NamestringThe name/label for source points. Appears in tooltips and cluster names.
If not defined, the latitude and longitude of the source points are used.
Target NamestringThe name/label for target points. Appears in tooltips and cluster names.
If not defined, the latitude and longitude of the target points are used.

Layer Attributes

Flow Layer attributes include Color, Fade, and Display.

Color

Color properties:

  • Color palette - Select a color palette to color the Flow Layer.

    Colors are mapped to the number of flow counts between a source and target point. (See Count in the table above.)

  • Dark base map - Enable/Disable dark base map mode.

    Toggle on if using a dark base map or toggle off if using a light base map to improve the clarity of flows.

  • Opacity slider - Slide to increase/decrease the opacity of the Flow Layer.

    Suggestion: Use May Overlay Blending to improve the visibility of base map features such as labels and roads.

Fade

Fade properties:

  • Fade toggle - Enable/Disable fading of flows.
  • Fade slider - Slide to fade flows with smaller Count values.
Left: Fade = 0; Right: Fade = 30.Left: Fade = 0; Right: Fade = 30.

Left: Fade = 0; Right: Fade = 30.

Display

Display properties:

  • Animation toggle - Enable/Disable animated flows.
Flow Layer animation.Flow Layer animation.

Flow Layer animation.

  • Clustering toggle - Enable/Disable clustering of flows.

    Clustering groups nearby source/target points to increase visibility, and adapts as you zoom in and out.

 Left: Clustering off; Right: Clustering on. Left: Clustering off; Right: Clustering on.

Left: Clustering off; Right: Clustering on.

  • Location Totals toggle - Enable/Disable location total circles.

    The size of the location total circles is based on the number of flows in and out of the location.

Left: Location totals off; Right: Location totals on.<br></br>Left: Location totals off; Right: Location totals on.<br></br>

Left: Location totals off; Right: Location totals on.

  • Adaptive Scales toggle - Enable/Disable adaptive scaling for flows.

    Adaptive scaling adjusts flow thickness based on flows inside the current viewport. When disabled, flow thickness is based on all flows on the map.

  • Max Top Flows to Show slider - Slide to increase/decrease the max number of flows displayed.

Properties

For details on how to programmatically specify layer properties, refer to the Layer Configuration specification.

Charts

The Flow Layer supports Tooltip Charts. Using the Tooltip Chart with the Flow Layer, you can display chart metrics in the mouse-over tooltip. This allows users to interactively explore the top origins and destinations for any given point on the map.

Follow these steps to create a Flow Layer chart:

1. Create a Flow Layer, then click Show Charts.

2. Click Add Chart, then select Tooltip Chart.

3. A chart of the flows will automatically generate. Click Chart Settings to configure the Tooltip Chart.

A Flow Chart showing Chicago rideshare data.A Flow Chart showing Chicago rideshare data.

A Flow Chart showing Chicago rideshare data.

The charts will update to the viewport when zooming to show the clustered locations for the current zoom level.

Chart Settings

OptionsDescription
TitleTitle of the Tooltip Chart.
LayerLayer to represent in the chart.
Field and AggregationThe type of information to display (based on the layer selected).
Show in TooltipIf enabled, displays chart metrics in the mouse-over tooltip.
Include Internal FlowsIf enabled, includes internal flow data in the chart metrics.

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