Universal Tracking Component

Section 5. The Universal Tracking Component

The Universal Tracking Component is our easiest way to get tracking data sent to any ARFX Camera or Rig. This component uses the location of any actor within the virtual scene to drive the ARFX Camera, circumventing the need to set up tracking directly onto it. This is especially useful with Live Link, which will try to override the camera’s location in virtual space which we do not want in regard to ARFX.

Remember, in ARFX, the screen itself is the world origin point of our tracking volume. If it doesn’t move, then the ARFX cameras will not do as well. What does move is just the so-called “inner frustum” in which the parallax effect is made.

Section 5.1 The Component

Unlike with the other Tracking Components, this one is fairly straightforward.

• Hero Tracker Actor - This allows you to assign any actor (virtual object) within the scene to act as your hero tracker. You can either use the drop-down menu to select from the full list of actors in the scene or the eye-dropper tool to simply click on the actor in the scene itself.

• Calibration Tracker Actor - This allows you to assign any actor (virtual object) within the scene to act as your calibration tracker. You can either use the drop-down menu to select from the full list of actors in the scene or the eye-dropper tool to simply click on the actor in the scene itself.

• Use Hero Tracker as Calibrator - When calibrating the component will send the Hero tracker’s data instead of the Calibrator’s. Not necessarily required as you can simply set the same actor on both Hero and Calibration.

Section 5.2 Modifications.

The settings found within this subsection are fully detailed within the Track_PositionModifiers Section.

Section 5.3 Assigning the Hero and Calibration Trackers.

In order to get your tracking data, it is up to you to assign the hero and calibration trackers to actors/objects in the scene that already have some form of tracking data attached to them (usually via Live Link). There are two ways of doing this: the drop-down or the eye-dropper tool.

The drop-down menu is great for when you know the exact name of the actor in which you want to use. Otherwise, the list can be too long.

The eye-dropper tool can be particularly useful in that you just click the object you wish to use. The downside is that semi-invisible objects in the scene can and will get in the way of your selection. Thankfully, Unreal does tell you what is under your mouse cursor at all times.

Section 5.4 Setting Up Your Tracked Actor.    

In order for this component to work, it requires that you create another actor in the scene for you to attach a tracking method like Live Link onto. It is often best to just use an empty Actor or a dummy Cine Camera Actor.

Adding a plain Actor in Unreal will create an empty invisible object in the scene. Since it is invisible, be sure to give it a good name!

Adding a plain Cine Camera Actor in Unreal will create a camera that is used for cinematics and virtual production. The reason you’d want to use this over an empty Actor is that you can add Lens Emulation that can then be used within the ARFX Camera.

Be sure to give these actors a name that fits their purpose so they can be easily searched for. Example: HeroTracker and CalibrationTracker.

Section 5.5 Setting Up Live Link on Any Actor.    

This information is covered in depth in Setting Up and Using Live Link or FreeD Section. Once you have tracking attached to your dummy Actors and your Universal Component, the ARFX Camera should be ready for use.

Section 5.6 About Calibration.                            

Unlike ViveTrackers, most tracking systems make use of bulky attachable tracking cameras that are often affixed to your physical camera. You cannot simply detach the tracker to calibrate every time you need to do so as they are often oriented precisely and sometimes even tied down semi-permanently.

Because of this, it is recommended you use a fixed calibration point in your tracking volume.