🤖 AI Summary
This work addresses geometric inconsistencies in text-to-video generation—such as object deformation, texture drift, and non-rigid background motion—by introducing a geometric consistency reward mechanism that explicitly optimizes temporal geometric structure during reinforcement fine-tuning of diffusion models. For the first time, geometric consistency is formulated as a directly optimizable objective without modifying the model’s latent space, making the approach applicable to complex dynamic scenes involving both camera and object motion. By integrating optical flow, depth-pose estimation, and feature correspondence techniques, the method effectively disentangles rigid background from dynamic object regions and evaluates their consistency separately. Experiments demonstrate that this approach substantially reduces temporal geometric artifacts while preserving high visual fidelity, outperforming strong existing baselines.
📝 Abstract
Generating geometrically consistent videos remains an open challenge: text-to-video diffusion models trained on web-scale data treat geometry only implicitly, leading to object deformation, texture drift, and non-rigid backgrounds under camera motion. Existing solutions either improve consistency as a byproduct, apply only to static scenes or realign the latent space of the model completely. We introduce a geometry-consistency reward that directly measures whether motion in a generated video is compatible with a coherent scene. Our key insight is that in physically consistent videos, background motion should be explainable by rigid camera-induced flow, while independently moving objects should preserve appearance identity along motion trajectories. We operationalize this using optical flow, depth--pose predictions, and feature-based correspondence to separate rigid and dynamic regions and evaluate their respective consistency. Integrating this reward with reinforcement fine-tuning transforms geometric consistency from an emergent property into an explicit optimization objective for video generators. The approach is model agnostic and applies to diverse dynamic scenes containing both camera and object motion. Experiments show substantial reductions in temporal geometric artifacts over strong baselines while preserving perceptual quality. Code and model weights are published.