Motion Forcing: A Decoupled Framework for Robust Video Generation in Motion Dynamics

TL;DR

This paper introduces Motion Forcing, a hierarchical framework that decouples physical reasoning from visual synthesis to improve robustness and physical consistency in complex video generation tasks.

Contribution

It proposes a novel Point-Shape-Appearance paradigm and masked point recovery strategy to enhance physical understanding and stability in video generation.

Findings

Outperforms state-of-the-art methods on autonomous driving benchmarks

Maintains physical consistency in complex scenes with collisions or dense traffic

Demonstrates generality across physics and robotics applications

Abstract

The ultimate goal of video generation is to satisfy a fundamental trilemma: achieving high visual quality, maintaining rigorous physical consistency, and enabling precise controllability. While recent models can maintain this balance in simple, isolated scenarios, we observe that this equilibrium is fragile and often breaks down as scene complexity increases (e.g., involving collisions or dense traffic). To address this, we introduce \textbf{Motion Forcing}, a framework designed to stabilize this trilemma even in complex generative tasks. Our key insight is to explicitly decouple physical reasoning from visual synthesis via a hierarchical \textbf{``Point-Shape-Appearance''} paradigm. This approach decomposes generation into verifiable stages: modeling complex dynamics as sparse geometric anchors (\textbf{Point}), expanding them into dynamic depth maps that explicitly resolve 3D geometry (\textbf{Shape}), and finally rendering high-fidelity textures (\textbf{Appearance}). Furthermore, to foster robust physical understanding, we employ a \textbf{Masked Point Recovery} strategy. By randomly masking input anchors during training and enforcing the reconstruction of complete dynamic depth, the model is compelled to move beyond passive pattern matching and learn latent physical laws (e.g., inertia) to infer missing trajectories. Extensive experiments on autonomous driving benchmarks show that Motion Forcing significantly outperforms state-of-the-art baselines, maintaining trilemma stability across complex scenes. Evaluations on physics and robotics further confirm our framework's generality.