World Model Applications

world-model applications use the learned environment-dynamics prior for three tasks — video prediction/understanding: V-JEPA predicts future representations in latent space without reconstructing pixels; video generation: Sora uses DiT with 3D VAE spatio-temporal compression (8× spatial, 4–8× temporal) to generate video, acting as a generative world model — in contrast to JEPA: JEPA seeks semantic representations, Sora seeks pixels; planning: in RL the world model generates 'imagined rollouts' for policy training and MPC planning (see the RL module, guide model-based-rl-and-planning).

video understanding/generation, embodied planning, world-model interviews; often asked: 'V-JEPA vs Sora positioning'.

understanding, generation, and decision-making are usually siloed; a world model unifies them with one dynamics prior — V-JEPA gets semantic representations cheaply, Sora validates dynamics through generation, and imagined rollouts raise RL sample efficiency by roughly an order of magnitude.

How is a world model used for video prediction, video generation, and planning? One representative model each?

V-JEPA vs Sora: essential difference (predict representations vs generate pixels)?

Why do imagined rollouts improve RL sample efficiency? How does model error affect planning quality?

What does Sora's 3D VAE spatio-temporal compression do? Compression ratios in space and time?

Practical difficulties of using generative video world models directly for planning?