Choosing the motion before rendering it
Convincing pixels do not automatically give an object a good route through a scene. OptiWorld brings classical optimal control into video generation at inference time: recover a task-relevant state, optimize a trajectory under physical constraints, then use it to guide rendering. The framework targets goal-conditioned generation, motion editing, and counterfactual futures. Paper abstract ↗
Understand, plan, generate
- Understand the scene. Geometry, segmentation, and vision-language reasoning assemble a compact 3D state. Editing also uses tracks from the source video.
- Plan the motion. A continuous manifold expresses goals, hazards, and efficiency as geometry. Risky regions become costly to traverse; smoothness regularizes the path. A voxel-graph seed is refined into a continuous trajectory.
- Generate the video. The first frame, prompt, and optimized 3D tracks guide a controllable generator. The paper uses Diffusion as Shader; the framework supports other generators with a compatible trajectory interface.
This shared planning geometry makes constraints comparable within one optimization. The modeled state is deliberately compact, rather than a complete physical simulation. Method in the paper ↗