This feature is available as of Unreal Engine 5.5.
The LODSync component manages the LODs for all the MetaHuman components to ensure a smooth transition between LODs.
The LODSync component coordinates the LODs of the Face, Eyelashes, Eyebrows, Hair, Mustache, Beard, Feet, Legs, and Torso components.
LODSync Component Settings
To configure the LODSync component, follow these steps:
Open your MetaHuman Blueprint and select the component in the Components window.
Go to the Details panel and expand the LOD section.
Here you can configure the total Number of LODs used, set a Forced LOD, and set a Minimum LOD used by the MetaHuman.
The number of LODs refers to the different versions of the components that come with the MetaHuman when imported into Unreal Engine. You can manually add additional LODs, but this workflow is not supported. Instead, we recommend adjusting the settings for the existing LODs, as shown in the Customize the LOD Settings section below.
The Forced LOD refers to a static LOD used for the MetaHuman no matter its size on the screen. A value of -1 means the LODs will switch automatically based on the screen size.
In the comparison below you can see the difference between a forced LOD 0 and LOD 3 of an Optimized MetaHuman.
Use this setting if you want to force a certain LOD to your MetaHuman no matter its screen size. An example would be a distant crowd where you want to ensure all MetaHumans remain at a specific LOD.
The Min LOD setting refers to the lowest LOD the MetaHuman will use, regardless of the screen size. By default this is LOD 0 (highest quality) when the camera is close to the MetaHuman (and the mesh takes a larger portion of the screen). However, you can set this to a higher value to improve performance. For example, you could set the Min LOD to 1, which will disable certain animation features, use hair cards instead of a groom, and use lower quality materials.
The Min LOD only sets the floor for LODs, they will continue to switch based on screen size as expected.
In the example above, we switched to the Wireframe mode to better visualize the difference in LODs. LOD 0 uses a more dense mesh for the MetaHuman and a hair groom (not shown in this view). Compare this to a Min LOD 1 which uses a more sparse character mesh and switches to hair cards for the hair (shows as geometry in this view).
Components to Sync
The LODSync component has a list of all components it manages, with each entry having the Name of the component and the Sync Option.
To view the list of components, select the LODSync component, go to the Details panel and expand the Components to Sync section.
Notice that by default, the Body and Face components have the Sync Option set to Drive. This means that these components will drive the other MetaHuman LODs, despite their individual LOD settings.
Other components, such as the Torso have a Sync Option set to Passive. This means that their LODs are being set by the components with a Drive Sync Option. You can customize these options to suit your needs. However, we recommend leaving these settings at their default value for best results.
Custom LOD Mapping
The LODSync component has a list of components where it applies a custom LOD mapping. This means that a certain LOD set by the LODSync component corresponds to another LOD for that specific component.
With the LODSync component selected, expand the Custom LOD Mapping section to see the default settings. In the example below, the Hair component has entries for LODs 0 to 4, with a custom mapping of 1, 3, 5, 7. This means that when the component sets the MetaHuman to LOD 0, the hair component will use its LOD 1 instead.
You can use this section to further customize how you set LODs per component. However, we recommend leaving the default settings, as we tested them to produce the best overall results.
Customize the LOD Settings
MetaHumans have separate LOD settings for the body and face. You can view and modify these settings by opening the corresponding data asset.
To view the LOD settings for the face, follow these steps:
Open your MetaHuman Blueprint and select the Face component of your MetaHuman.
Go to the Details panel and scroll down to the Mesh section.
Click the navigation button for the head mesh to go to the asset’s location in the Content Browser and open it.
In the Skeletal Mesh editor, go to the Asset Details window and scroll down to the LOD Settings.
Click the Navigation button for the LOD Settings to navigate to the data asset in the Content Browser.
Open the data asset and expand the LOD Groups section to see details about each LOD.
Notice how each LOD has a specific Screen Size setting. This value represents the screen size considered when switching to that LOD. For example, LOD 1 has a Screen Size of 0.2, which means that the mesh will switch from LOD 0 to LOD 1 once the mesh is less than 20% of the size of the screen.
You can adjust these values to determine when the head mesh switches between LODs, thus affecting performance.
For this next example, you will modify the screen size of LOD 0 and 1:
Set the LOD 0 Screen Size to 1.0 and the LOD 1 Screen Size to 0.5.
Save the asset and go back to the Skeletal Mesh editor.
Click Regenerate to build the LODs with the new settings and move away from the head in the viewport.
Notice that the head switches to LOD 1 when the screen size is less than 0.5.
To view the LOD settings for the body, follow these steps:
Open your MetaHuman Blueprint and select the Body component of your MetaHuman.
Go to the Details panel and scroll down to the Mesh section.
Click the navigation button for the body mesh to go to the asset’s location in the Content Browser and open it.
In the Skeletal Mesh editor, go to the Asset Details window and scroll down to the LOD Settings.
Click the navigation button for the LOD Settings to navigate to the data asset in the Content Browser.
You can now modify the LOD settings in the same way you modified the head LOD settings.
