Use marker data via Blueprints

This page details how to access marker data through Blueprints.

In previous versions of the Vicon plugin for Unreal Engine 5.2, you could access marker data through a custom ViconMarker Role. In version 1.8.0, this has been changed to use the Live Link Basic Role instead. The Animation and Transform Role subjects have their marker data included in their metadata. As you can no longer directly access this data, two new functions are provided that enable you to access marker data.

Access marker data by name

Create a Blueprint and open it (or open an existing Blueprint).
Click Add and select Live Link Controller.

Tip: When adding a component, search for Live Link.
Select LiveLinkComponentController and in the Details panel, go to the Events section and add an On Live Link Updated event.
From this event node drag the pin out and add it to the Evaluate Live Link Frame node.
In the Evaluate Live Link Frame node, go to the Subject field and select the Subject for which to display markers.
Set the Role to Basic Role.
Compile and save. Be sure to check the Role does not change on compile.
Drag the Data Result pin to bring up an action node.
In the action node, add either a Get Marker Translation by Name or Get Marker Translations node.

Examples of accessing marker data

The following examples illustrate how to access marker data using the functions provided for this purpose.

Offset marker translation

Both these examples contain a Get World Location node. This node accesses the location of the Blueprint's default Scene Root, which is then added to the marker translations to allow for offsets of the marker locations.

Example of using Get Marker Translation By Name

To use the Get Marker Translation By Name node, you must input the name for the specific marker to use into the Marker Name field.

To view marker names, hover the mouse pointer over the labeled marker in your Vicon software.

The tooltip shows the subject name followed by the marker name.

The following image shows the tooltip for the marker named C7.

You can use the same method to find the marker name for props.

The following image shows an example of using the Debug Draw Sphere function to visualize the C7 marker of the subject.

The following image is the result of the Debug Draw Sphere function in UE.

Example of using Get Marker Translation

The Get Marker Translation node returns an array of marker translations.

This node is most useful when you need to access all markers of a subject or when there are unlabeled markers. You can't use the Marker Translation By Name node to do this as unlabeled markers are not accessible via this node.

In this case, as shown in the following example, use the Get Marker Translation node to return all markers of a selected subject.

The following image is the result of the Get Marker Translation node in UE.