No MoCap Needed: Post-Training Motion Diffusion Models with Reinforcement Learning using Only Textual Prompts

Fuente: arXiv
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Hauptverfasser: Macaluso, Girolamo, Mandelli, Lorenzo, Bicchierai, Mirko, Berretti, Stefano, Bagdanov, Andrew D.
Format: Preprint
Veröffentlicht: 2025
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author Macaluso, Girolamo
Mandelli, Lorenzo
Bicchierai, Mirko
Berretti, Stefano
Bagdanov, Andrew D.
author_facet Macaluso, Girolamo
Mandelli, Lorenzo
Bicchierai, Mirko
Berretti, Stefano
Bagdanov, Andrew D.
contents Diffusion models have recently advanced human motion generation, producing realistic and diverse animations from textual prompts. However, adapting these models to unseen actions or styles typically requires additional motion capture data and full retraining, which is costly and difficult to scale. We propose a post-training framework based on Reinforcement Learning that fine-tunes pretrained motion diffusion models using only textual prompts, without requiring any motion ground truth. Our approach employs a pretrained text-motion retrieval network as a reward signal and optimizes the diffusion policy with Denoising Diffusion Policy Optimization, effectively shifting the model's generative distribution toward the target domain without relying on paired motion data. We evaluate our method on cross-dataset adaptation and leave-one-out motion experiments using the HumanML3D and KIT-ML datasets across both latent- and joint-space diffusion architectures. Results from quantitative metrics and user studies show that our approach consistently improves the quality and diversity of generated motions, while preserving performance on the original distribution. Our approach is a flexible, data-efficient, and privacy-preserving solution for motion adaptation.
format Preprint
id arxiv_https___arxiv_org_abs_2510_06988
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle No MoCap Needed: Post-Training Motion Diffusion Models with Reinforcement Learning using Only Textual Prompts
Macaluso, Girolamo
Mandelli, Lorenzo
Bicchierai, Mirko
Berretti, Stefano
Bagdanov, Andrew D.
Computer Vision and Pattern Recognition
Diffusion models have recently advanced human motion generation, producing realistic and diverse animations from textual prompts. However, adapting these models to unseen actions or styles typically requires additional motion capture data and full retraining, which is costly and difficult to scale. We propose a post-training framework based on Reinforcement Learning that fine-tunes pretrained motion diffusion models using only textual prompts, without requiring any motion ground truth. Our approach employs a pretrained text-motion retrieval network as a reward signal and optimizes the diffusion policy with Denoising Diffusion Policy Optimization, effectively shifting the model's generative distribution toward the target domain without relying on paired motion data. We evaluate our method on cross-dataset adaptation and leave-one-out motion experiments using the HumanML3D and KIT-ML datasets across both latent- and joint-space diffusion architectures. Results from quantitative metrics and user studies show that our approach consistently improves the quality and diversity of generated motions, while preserving performance on the original distribution. Our approach is a flexible, data-efficient, and privacy-preserving solution for motion adaptation.
title No MoCap Needed: Post-Training Motion Diffusion Models with Reinforcement Learning using Only Textual Prompts
topic Computer Vision and Pattern Recognition
url https://arxiv.org/abs/2510.06988