DNA Asset Reference

The MetaHuman DNA asset is a configurable asset that changes how MetaHuman DNA is authored, imported, configured, cooked, and runtime-evaluated. The DNA asset provides a way to:

• Configure DNAConfig, pick coordinate systems, and tune in platform RigLogic settings.

• Integrate MetaHuman characters into runtime games.

• Upgrade projects from 5.7 or earlier to 5.8 with a scriptable migration path.

How DNA Differs From UDNA

In MetaHuman 5.8 the DNA asset replaces the UDNAAssetAssetUserData pattern and appears in the content browser as a standalone asset, where previously the DNA asset was stored in the USkeltalMesh.

5.8 DNA Features

• Generalized coordinate-system conversion: DNA can be loaded into, and re-emitted in any of the following:

  • Target coordinate system.

  • Rotation convention.

  • Face winding order, driven by a fully-described FDNAConfig.

• Dedicated UDNA asset type: A first-class, standalone DNA asset with its own content browser entry, replacing the UDNAAsset AssetUserData pattern.

• Project-level RigLogic settings: You can find a RigLogic page by opening Project Settings > Plugins > RigLogic. The page provides per-import defaults that apply to every newly imported DNA asset.

• Per-platform DNAConfig and RigLogicConfiguration: Both structs carry per-platform fields that are flattened to the cook target during PreSave, so each platform ships only the LODs and runtime parameters it needs.

• Optimized cooked serialization: Cooked DNAs serialize the already-initialized FRigLogic state directly into the archive instead of raw DNA bytes, delivering ~50× faster runtime initialization.

• Headless migration commandlet: (ConvertLegacyDNAAssets) for upgrading existing projects.

How DNA Works in 5.8

• Performs general-case coordinate-system conversion on every spatial channel of the DNA: neutral joint translations and rotations, joint deltas, vertex positions and normals, blend-shape deltas, RBF solver raw control values, and face winding.

• Promotes DNA to a content-browser-discoverable asset (UDNA) with:

  • Import.

  • Export.

  • Create-from-legacy actions.

• Provides a way for a project to declare default LOD ranges, calculation backend, FP precision, multi-threaded ML toggle and layer load flags once, in Project Settings, and have them applied to every newly imported DNA.

• Applies in-place edits, such as:

  • Editing DNAConfig on a UDNA re-runs the converter against the in-memory bytes.

  • Rebuild the runtime context with needing to reimport.

• At cook time, flattens per-platform values into the Default slot for the target platform; cooked archives carry only minimum-runtime DNA + a serialized RigLogic state.

• At load time, restores FRigLogic directly from the archive instead of rebuilding from DNA bytes.

• Migrates legacy UDNAAsset user-data to standalone UDNA assets in a single, scriptable, source-control-aware pass.

Find the DNA Asset

When you open any existing UE 5.8 project there is no plugin install required. DNA and RigLogic are shipped with the engine in Engine/Plugins/Animation/RigLogic (the same place it lived in 5.7). The legacy UDNAAsset class is preserved and renamed in the editor to "Legacy MetaHuman DNA Data" so existing 5.7 content keeps loading. The new UDNA is what a fresh import produces.

UDNA in Unreal Engine

To find your UDNA assets in Unreal, look in the following places in the engine:

• Project Settings > Plugins > RigLogic

  A new section for project-wide DNA import defaults.

• Content Browser

  A new UDNA asset type (display name: DNA), with right-click actions on both USkeletalMesh (import / create from legacy) and UDNA (export).

• Asset editor / Details panel

  The UDNA exposes DNAConfig, RigLogicConfiguration, bKeepDNAAfterInitialization, bUseOptimizedCooking, MetaData. Custom property panels render the coordinate-system editor and the per-platform enum dropdowns.

• Asset Registry

  The USkeletalMesh rows now expose a "DNA" tag identifying the associated DNA name.

• Command line

  A new -run=ConvertLegacyDNAAssets commandlet.

UDNA User Interface

Specific new UI elements include:

• Project Settings > Plugins > RigLogic :

  Default DNA Config and Default RigLogic Configuration sections.

  

• Content Browser > right-click on a USkeletalMesh > MetaHuman DNA submenu :

  Import DNA Asset, Create DNA Asset (visible only on meshes still carrying a legacy UDNAAsset).

• Content Browser > right-click on a UDNA > Export DNA.

• UDNA Details panel > DNA category :

  The full FDNAConfig (Layers bitmask, Max/Min LOD per platform, Exact LODs, coordinate-system policy + axes + rotation sign + sequence + face winding).

• UDNA Details panel > RigLogic category :

  Per-platform calculation type, per-platform FP type, per-platform multi-thread ML toggle, layer load flags, joint representation toggles, pruning thresholds.

• UDNA Details panel > top-level :

  bKeepDNAAfterInitialization, bUseOptimizedCooking, MetaData.

• Custom property panel: coordinate system :

  Three coherent X/Y/Z dropdowns plus an Apply button that gates commit on a valid basis (3 distinct spatial axes, |det(B)|≈1).

• Custom property panel: per-platform enums :

  Render enum dropdowns instead of integer spinners inside the per-platform widgets for CalculationTypePerPlatform and FloatingPointTypePerPlatform.

5.8 DNA Workflows

Before you can work directly with the UDNA asset you must do the following:

1. Install Unreal Engine 5.8.

2. A project containing (or about to import) MetaHuman DNA content.

3. For the migration path, have an existing UE 5.7-or-earlier project carrying legacy UDNAAsset user-data on USkeletalMesh assets.

4. For the cook-time benefits, target at least one platform configuration (Mobile, PS5, XSX, Switch, etc.) where you intend to override LODs or FP type.

Configure Project-Wide DNA Import Defaults

1. Open Project Settings.

2. Navigate to Plugins > RigLogic.

3. Expand Default DNA Config:

   • Set Layers (which layers to load — Descriptor, Definition, Behavior, Geometry, GeometryNoBlendShapes, MLBehavior, RBFBehavior).

   • Set Max LOD and Min LOD per-platform overrides as needed (Mobile, Desktop, Console, and so on).

   • Set Coordinate System Transform Policy (Preserve / Transform), Coordinate System, Rotation Sign, Rotation Sequence, Face Winding Order if your studio's source DNAs aren't in UE-native space.

4. Expand Default RigLogic Configuration:

   • Set Calculation Type per platform (Scalar, SSE, AVX, NEON, AnyVector).

   • Set Floating Point Type per platform (Float, HalfFloat, Auto). Auto resolves to Float on Desktop, HalfFloat elsewhere at cook time.

   • Set Enable multi-thread ML Compute per platform.

   • Toggle layer loads (LoadJoints, LoadBlendShapes, LoadAnimatedMaps, LoadMachineLearnedBehavior, LoadRBFBehavior, LoadTwistSwingBehavior).

5. Save your project. Defaults apply to every newly imported DNA. Reimports preserve each asset's already-saved settings.

Import a New .dna File

1. In the content browser, choose Import (or drag the .dna file in).

2. The importer auto-detects the source format. Legacy MetaHuman DNAs (DBName FN or FN_MH_v2) without geometry are loaded under FDNAConfig::Legacy() to remain compatible with already-imported SkeletalMeshes. Other sources start from the project default.

3. A new UDNA asset is created. The asset carries the project default RigLogicConfiguration.

4. Right-click the target USkeletalMesh > MetaHuman DNA > Import DNA Asset to attach the new UDNA via UDNAAssetUserData.

Edit a DNA's Coordinate System After Import

1. Open a UDNA asset.

2. On MaxLODPerPlatform, MinLODPerPlatform, CalculationTypePerPlatform, FloatingPointTypePerPlatform, EnableMultiThreadMLComputePerPlatform, select the +Add icon to add an override for a target platform group (Mobile, Desktop, Console, and more) or a specific platform.

3. Pick the desired enum / value. The Default value is used for any platform without an override.

4. Save. At cook time, UDNA::PreSave flattens the per-platform value for the cook target into the Default slot. Auto FP type resolves to Float on Desktop, HalfFloat elsewhere.

Migrate a 5.7 Project to the 5.8 DNA Layout

1. Make sure source control is checked in / clean.

2. Run a dry-run first to preview changes:

   Command Line

   UnrealEditor-Cmd.exe MyProject.uproject ^
       -run=ConvertLegacyDNAAssets ^
       -PathFilter=/Game/MetaHumans ^
       -DryRun -Verbose -Unattended

   Copy full snippet(4 lines long)

3. Review the printed Phase 1 / Phase 2 summary.

4. Apply (single-step layout migration + version bump):

   Command Line

   UnrealEditor-Cmd.exe MyProject.uproject ^
       -run=ConvertLegacyDNAAssets ^
       -PathFilter=/Game/MetaHumans ^
       -ResaveDNA ^
       -AutoCheckOut -AutoCheckIn -Unattended ^
       -NoSplash -NullRHI -stdout -FullStdOutLogOutput

   Copy full snippet(6 lines long)

5. Verify each USkeletalMesh now carries a MetaHuman DNA Data (UDNAAssetUserData) entry pointing to a standalone UDNA asset.

The full commandlet reference (all switches, behaviour details, examples, output format) lives in the companion technical document UE5.8_DNA_RigLogic_PreDoc.md § Legacy → 5.8 migration.

Known Limitations and Potential Risks

The following are known limitations potential risks of working with UDNA:

Bone-track animations on non-UE-native rigs

A UDNA can be loaded into any target coordinate system, and the resulting SkeletalMesh renders correctly. 

However, bone-track animations carry absolute joint transforms baked in UE-native space and will deform a non-UE-native rig incorrectly. Curve-only AnimSequence data is space-agnostic and is the safe choice on non-UE-native rigs. Recommend ship-targeted DNAs stay in UE-native coordinates unless the workflow is curve-only.

DNA LOD count and face USkeletalMesh LOD count must match 1:1 at runtime

FAnimNode_RigLogic calls RigInstance > SetLOD(SkelMesh.GetLODLevel()) — the SkelMesh's current LOD index is fed straight to the DNA as the DNA LOD index. So the DNA's LOD pyramid (driven by FDNAConfig.MaxLODPerPlatform / MinLODPerPlatform / ExactLODs) and the face SkelMesh's LOD list must contain the same number of entries.

Editing one without editing the other (for example, dropping a SkelMesh LOD without adjusting Max/MinLODPerPlatform, or vice versa) will cause RigLogic to evaluate against an LOD index the DNA does not contain, producing missing blend-shape activations or skipped rig evaluation.

The right places to drive both together: at build time edit FMetaHumanLODProperties.FaceLODs / BodyLODs on the MetaHuman Default Editor Pipeline (which selects which DNA LODs are baked into the built MetaHuman); at runtime / per-platform edit FDNAConfig.Max/MinLODPerPlatform on the UDNA and the SkeletalMesh's USkeletalMeshLODSettings for the same platform.

Per-platform mismatches only surface in cooked builds.

Don't conflate the DNA↔SkelMesh 1:1 rule with actor-level LOD remapping

When the actor needs to expose a different LOD count than the underlying face / body SkelMeshes (for example, an actor with 4 perceived LODs driving a face mesh that only has 2 distinct meshes), use ULODSyncComponent::CustomLODMapping (TMap<FName, FLODMappingData>, where FLODMappingData::Mapping is a TArray<int32> from actor-LOD index → component-LOD index).

The MetaHuman Character Editor wires this through IMetaHumanCharacterEditorActorInterface::InitializeMetaHumanCharacterEditorActor, which takes int32 InNumLODs, TArray<int32> InFaceLODMapping, TArray<int32> InBodyLODMapping.

An example from the in-source docs: InNumLODs=4, InFaceLODMapping={0,0,1,1} means actor LODs 0..1 use face LOD 0, actor LODs 2..3 use face LOD 1. This remap sits above the rig-evaluation layer; the DNA-to-face-SkelMesh relationship below it is still 1:1. Reference implementation: AMetaHumanCharacterEditorActor.

FAnimNode_RigLogic.LODThreshold is a perf knob, not a mapping

It is the maximum SkelMesh LOD level at which RigLogic still evaluates (default INDEX_NONE = always evaluate). Above the threshold, the node returns the input pose unchanged. Setting it lower is a performance / quality trade-off; it does not paper over a count mismatch between DNA LODs and SkelMesh LODs.

Project defaults versus reimport

Reimporting an existing asset preserves that asset's already-saved settings. Project defaults only affect newly imported DNAs. Editing Project Settings > Plugins > RigLogic does not retroactively re-tune existing assets.

bUseOptimizedCooking = false reverts to the legacy cooked path. No RigLogic state dump in the archive, larger cooked payloads, and the loss of the ~50× runtime-init speedup. Default is true; only disable for debugging.

ConvertLegacyDNAAssets with -ReimportFromSource and a missing source .dna

If a mesh's original .dna is missing on disk and a <Mesh>_DNA already exists, the commandlet does not fall back to in-place conversion — it skips with Already migrated (intentional, to avoid stomping custom config).

Editing FDNAConfig.Layers invalidates the FDNAIndexMapping cache

The asset handles this automatically. Third-party code holding a long-lived TSharedPtr<FDNAIndexMapping> outside the asset must rebuild after a config change. 

Legacy class label confusion

In 5.8, UDNAAssetUserData (the new wrapper) shows in the editor as "MetaHuman DNA Data", while the legacy UDNAAsset shows as "Legacy MetaHuman DNA Data". Tutorial videos / screenshots using the old "MetaHuman DNA Data" label now refer to a different class. Existing screenshots need re-capturing.

Coordinate-system editor commits on Apply, not on each axis change

Editing X/Y/Z dropdowns stages the change; the Apply button is only enabled when the staged basis is valid. Users dragging values around should not expect live updates — this is intentional, to prevent transient invalid bases from triggering full DNA reloads.

DCC export guidance for non-UE-native targets

The Maya  and Houdini export tooling has not been updated as part of 5.8. Studios using MetaHuman for Maya and MetaHuman for Houdini should continue to author in the established conventions and let the importer convert at load time.