LiftAvatar: Kinematic-Space Completion for Expression-Controlled 3D Gaussian Avatar Animation

Hualiang Wei; Shunran Jia; Jialun Liu; Wenhui Li

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arXiv · 2603.02129

LiftAvatar: Kinematic-Space Completion for Expression-Controlled 3D Gaussian Avatar Animation

Hualiang Wei·Shunran Jia·Jialun Liu·Wenhui Li

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Abstract

We present LiftAvatar, a new paradigm that completes sparse monocular observations in kinematic space (e.g., facial expressions and head pose) and uses the completed signals to drive high-fidelity avatar animation. LiftAvatar is a fine-grained, expression-controllable large-scale video diffusion Transformer that synthesizes high-quality, temporally coherent expression sequences conditioned on single or multiple reference images. The key idea is to lift incomplete input data into a richer kinematic representation, thereby strengthening both reconstruction and animation in downstream 3D avatar pipelines. To this end, we introduce (i) a multi-granularity expression control scheme that combines shading maps with expression coefficients for precise and stable driving, and (ii) a multi-reference conditioning mechanism that aggregates complementary cues from multiple frames, enabling strong 3D consistency and controllability. As a plug-and-play enhancer, LiftAvatar directly addresses the limited expressiveness and reconstruction artifacts of 3D Gaussian Splatting-based avatars caused by sparse kinematic cues in everyday monocular videos. By expanding incomplete observations into diverse pose-expression variations, LiftAvatar also enables effective prior distillation from large-scale video generative models into 3D pipelines, leading to substantial gains. Extensive experiments show that LiftAvatar consistently boosts animation quality and quantitative metrics of state-of-the-art 3D avatar methods, especially under extreme, unseen expressions.

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BibTeX RIS

Hualiang Wei, Shunran Jia, Jialun Liu, Wenhui Li. 2026-03-02. LiftAvatar: Kinematic-Space Completion for Expression-Controlled 3D Gaussian Avatar Animation. https://arxiv.org/abs/2603.02129

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