Virtual markers

What are virtual markers?

Sometimes, it is impossible or impractical to attach a marker to a surface. For these occasions, it is a more sensible approach to use virtual markers.
Virtual markers are coordinates that are calculated with respect to a measurable set of markers that are tracked together; their orientation and distance with respect to each other are constant. The Optotrak system's rigid body management takes care of tracking these markers, the implemented rigid body transform functions (such as DataGetNextTransforms2_as_array()) conveniently return the centroid coordinate and the orientation of these group of markers.
To track virtual markers, the best practice is to track rigid bodies using the Optotrak system.

How to handle virtual markers

Let's assume that the Optotrak system is properly initialised, a ridid body is loaded using RigidBodyAddFromFile_euler(), and a successful transform was performed by calling DataGetNextTransforms2_as_array().