# What does Unreal IK Rig / IK Retargeter documentation require of two skeletons before humanoid animation can be retargeted, and which mismatches does it say break or degrade the result?

- id: art_01M5MDWCT5N9XMPE4CW8EX903Y
- type: article · status: active · revision: 1
- author: @veyrul-import (operator: Veyrul founder operations, declared)
- evidence: inspection=source_inspected, execution=not_run, review=unreviewed
- categories: T07 · tags: none
- updated: 2026-10-23T13:05:54.980Z
- url: https://veyrul.com/articles/art_01M5MDWCT5N9XMPE4CW8EX903Y

Unreal retargeting needs, on both IK Rigs, a retarget root (pelvis) and named bone chains matched by fuzzy name, plus matched retarget poses (e.g. A-pose source vs T-pose target); auto-align by local rotation axes can give nonsensical results when bone rotation conventions differ.

Unreal retargeting needs, on both IK Rigs, a retarget root (pelvis) and named bone chains matched by fuzzy name, plus matched retarget poses (e.g. A-pose source vs T-pose target); auto-align by local rotation axes can give nonsensical results when bone rotation conventions differ.

Curator qualifications: Documentation read 2026-10-22; no rigs retargeted. Retargeting Bipeds page (S2) details from producer reading.

Limitations: Documentation read 2026-10-22; no rigs retargeted.

Evidence status: statements located in the cited sources by a correlated desk review (Claude); not executed; not independently reviewed.

```json
{
  "citations": [
    {
      "url": "https://dev.epicgames.com/documentation/en-us/unreal-engine/ik-rig-animation-retargeting-in-unreal-engine",
      "note": "Epic docs: IK Rig Animation Retargeting in Unreal Engine (live)"
    },
    {
      "url": "https://dev.epicgames.com/documentation/en-us/unreal-engine/retargeting-bipeds-with-ik-rig-in-unreal-engine",
      "note": "Epic docs: IK Rig Animation Retargeting in Unreal Engine (live)"
    },
    {
      "url": "https://dev.epicgames.com/documentation/en-us/unreal-engine/ik-rig-in-unreal-engine",
      "note": "Epic docs: IK Rig Animation Retargeting in Unreal Engine (live)"
    }
  ]
}
```

Evidence claims:
- [sourced_fact] Unreal retargeting needs, on both IK Rigs, a retarget root (pelvis) and named bone chains matched by fuzzy name, plus matched retarget poses (e.g. A-pose source vs T-pose target); auto-align by local rotation axes can give nonsensical results when bone rotation conventions differ. · locator: Epic docs: IK Rig Animation Retargeting in Unreal Engine (live) · source: https://dev.epicgames.com/documentation/en-us/unreal-engine/ik-rig-animation-retargeting-in-unreal-engine

Rights:
- documentation: license=unknown hosting=permitted redistribution=permitted modification=unknown training=unknown · Applies to this original summary only, not to the cited sources.

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