Setting Up and Using Live Link or FreeD

Section 3. Setting Up and Using Live Link or FreeD

For many within the virtual production industry, tracking is the one detail that is locked in early on. In Unreal Engine, that usually means making use of their built-in Live-Link system, a semi-open network messaging service that can be branched out to include any tracking standard.

Many of the major virtual tracking hardware brands make use of it, whether directly or through other protocols that are supported by Live Link, and for ARwall, we do so rather indirectly via Universal Tracking Component.

Section 3.1 Network Setup.      

Every tracking system has its own proprietary means of getting data from its hardware to the PC, and most have opted to use a networking solution that is connected directly to the host machine or through repeater systems. We will not go over how to do this networking as it is often a contractor that does this for you, so the best advice we can give here is to simply get it working and to leave it be.

Most machines have two or more ethernet ports to use, so it is highly recommended that you use one dedicated to the internet or private network and the other dedicated solely to Live Link.

Important

If you are using consumer-grade tracking like with either our ARFX Mobile App or the Vive Mars, then we recommend using a DHCP-enabled router. These networking devices provide local IP addresses to each device connected to it, saving you from having to manually assign IP addresses to yourself. This is especially of note if you are using privately managed networks such as those found in universities or commercial buildings as they may have restricted certain key networking features such as UDP messaging.

Section 3.2 In Unreal Editor: UDP Messaging.                          

When using Live Link in Unreal Editor, the system under the hood will use the first Network Adapter it finds for the Live Link protocol. If you have more than one Network Adapter in your machine, this may cause issues if you expect to receive tracking data from a particular adapter. If you want to receive UDP data on a specific Network Adapter, you will need to modify your Project Settings by going to Edit > Project Settings > UDP Messaging and changing the Unicast Endpoint.

Using the drop-down menu will reveal the list of Network Adapters available on your machine.

For example, if you have two adapters:        

Adapter A: XX.X.XXX.123

Adapter B: XXX.XXX.X.53.

If you want to receive data from the Live Link Message Bus Source on Network Adapter B, you will need to set your Unicast Endpoint to: XXX.XXX.X.53:0

The "":0"" specifies that all ports should be listed to._

Section 3.3 How to figure out your machine’s local IP address.

A good idea is to unplug everything and connect only one port to figure out which port is which.  

The universal way in Windows to figure out your computer’s IP Address is to search for Network Connections in the Windows Start Menu. Within the Network Connections menu, there will be a list of connections available to your computer. Find the one used by the connection between your computer and the Vive Mars and double-click it > Details > IPv4 Address to find your IP address for that port.

Important

While you are here it is highly recommended to rename your computer’s network adapters to what they are being used for by right click the connection and use Rename. If it is for the internet, just name it Internet Port. If it is for the Vive Mars, Vive Mars

Section 3.4 Setting Up Unreal for Live Link or FreeD.

Live Link is Unreal’s all-in-one tracking protocol, and as of Unreal 5.5, it is expanding to include other protocols used in a variety of industries.

First, you will have to make sure the Live Link Plugin is enabled by going to Edit > Plugins > and searching for Live Link in Unreal Editor. Please refer to the image above.

Enable Live Link and LiveLinkFreeD, and once you do, Unreal will give you a message asking you to restart the editor for the changes to take hold. Optionally, if you plan to use any sort of LensEmulation, then we also recommend turning on LiveLinkLens as this adds support for this through both tracking protocols.

Section 3.5 The Live Link Menu.

This menu is for both Live Link and Live Link FreeD. Feel free to skip this if you plan to use ARwall’s FreeD Component.

Once the plugin is running and Unreal restarted, go to Window > Virtual Production > Live Link to see a menu like the one in the above image.

Clicking on +Source will give you a list of Live Link Sources to which you can connect.    

For Live Link: Assuming you have the Vive Mars running and connected to the same network as the host machine and you’ve set UDP Messaging correctly (if necessary), then as soon as you are shown the list of available sources, you should see the Vive Mars immediately show up on the list. Clicking on that source will add it and any trackers associated with it within the menu.

FreeD requires you to input some information first.      

For FreeD: You must first input your host machine’s local IP address of the port that is connected to your Vive Mars. Do not use the IP address of the Vive Mars itself.      

You can find this IP within the  “How to figure out your machine’s local IP address” section above. The Port is the same one assigned on your Vive Mars’ Camera Tracking Protocols settings page. If everything is set up correctly, once you click Add the subject list below, the sources will populate with the trackers attached to the Vive Mars.  

Important

Due to the nature of UDP networking, only one port can be “opened” by your computer at a time. In other words, if you plan to use ARwall’s FreeD Tracking Component, you will be forced to use a different port than the default found in Unreal's Live Link implementation of FreeD. By default ARwall's port is set to 41000 where as Live Link's is 40000. As an aside, both methods work exactly the same way but the Tracking Components you will be using will be vastly different.        

Section 3.6 A brief on using Live Link within your scene.

While we will not go too in-depth about how to use Live Link, as it is best to refer to Unreal’s LiveLinkDocs, we will at least briefly cover how to add your tracker to a dummy Cine Camera within your scene.

First, start by adding a Cine Camera Actor to your scene.  

Then, with your camera selected, add a Live Link Controller to its list of components.

Finally, select the newly added Live Link Controller in the component list and use the drop-down in Subject Representation to assign it a tracker found within Live Link.

After following the above images, you should see your Cine Camera change position in the scene (usually somewhere near 0,0,0). If you move the assigned tracker, you will find that it is now tracking in real time! This is the basis for normal Virtual Production in Unreal, one in which can run both within the editor and while in PlayInEditor mode.

If you wish to continue using Live Link for tracking with ARFX, please refer to the Universal Tracking Component Section for more information. If you wish to use ARwall’s own FreeD Tracking Component, please refer to the ARwall's FreeD Tracking Component Section instead.