ReCHOIR: Contact-guided Human Object Interaction Retargeting to Diverse Characters

ReCHOIR is a new contact-guided motion retargeting approach aimed at human-object interaction, not just body motion. The core idea is to transfer an interaction sequence from one humanoid character to another while keeping the semantics of the action intact and maintaining believable contact with the object being manipulated.

That matters because standard retargeting often breaks down at the interaction layer: a grab, push, lift, or tool use may look fine on the source rig but drift once mapped to a character with different proportions or joint layout. ReCHOIR addresses this by conditioning the target motion on source contact cues and object geometry, then refining the motion in a body-part-aware latent space.

The system is built around a Part-Aware Motion Embedding autoencoder that encodes full-body motion into a shared representation across heterogeneous skeletons. On top of that, a contact-guided retargeting module injects object- and contact-related signals through a residual control branch, while a separate object motion decoder predicts a matching object trajectory for the target character.

For game teams, the practical appeal is clear: interaction-heavy animation sets are expensive to hand-polish, especially when a project supports multiple character body types. A method like this could reduce cleanup work for gameplay animation, cinematic pipelines, and tool-assisted content generation, particularly where props and hand contact need to stay consistent across rigs.