MotionCrafter: Dense Geometry and Motion Reconstruction with a 4D VAE

• URL: http://arxiv.org/abs/2602.08961v1
• Date: Mon, 09 Feb 2026 17:58:12 GMT
• Title: MotionCrafter: Dense Geometry and Motion Reconstruction with a 4D VAE
• Abstract summary: MotionCrafter is a video diffusion-based framework that jointly reconstructs 4D geometry and estimates dense motion from a monocular video.<n>We show that MotionCrafter achieves state-of-the-art performance in both geometry reconstruction and dense scene flow estimation.
• Score: 95.16927402591227
• License: http://creativecommons.org/licenses/by-nc-sa/4.0/
• Abstract: We introduce MotionCrafter, a video diffusion-based framework that jointly reconstructs 4D geometry and estimates dense motion from a monocular video. The core of our method is a novel joint representation of dense 3D point maps and 3D scene flows in a shared coordinate system, and a novel 4D VAE to effectively learn this representation. Unlike prior work that forces the 3D value and latents to align strictly with RGB VAE latents-despite their fundamentally different distributions-we show that such alignment is unnecessary and leads to suboptimal performance. Instead, we introduce a new data normalization and VAE training strategy that better transfers diffusion priors and greatly improves reconstruction quality. Extensive experiments across multiple datasets demonstrate that MotionCrafter achieves state-of-the-art performance in both geometry reconstruction and dense scene flow estimation, delivering 38.64% and 25.0% improvements in geometry and motion reconstruction, respectively, all without any post-optimization. Project page: https://ruijiezhu94.github.io/MotionCrafter_Page

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