A world model that predicts the video and the 3D trajectory at the same time
AspireAI community · arXiv
Existing video world models leave 3D dynamics implicit, action-based formulations are tied to one robot configuration, and 3D motion models get supervision only from flow, which is a weak signal about physical dynamics. WorldFlow is a generative world model that jointly predicts future video and query-based 3D trajectories, parameterising 3D motion as continuous displacement tokens aligned with the video grid and denoising both modalities with one Mixture-of-Transformers backbone under a rectified-flow objective. It was trained on 1.44 million object-level samples spanning simulated and real domains, with a new benchmark of 1,678 evaluation samples from 11 sources including spatial reasoning tasks. Reported results: lowest average displacement error and final displacement error among the evaluated learning-based methods, an ADE of 0.060 m on the SpatialCog set (54.2% below the strongest external baseline), and 55.9%/68.5% reductions in ADE/FDE against its own flow-only variant.
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Two sparse-autoencoder analyses have resisted scaling: matching semantically similar features across layers, and compressing large feature circuits into interpretable supernodes. This paper argues both are the same underlying problem, estimating semantic distances between SAE features that sit on different activation manifolds. Its representation treats each feature not as a single decoder vector but as an activation-weighted distribution over the hidden states expressing it, projects those distributions into a shared reference space, and compares them with Wasserstein distance. The representation is proved invariant to activation rescaling and stable under perturbation, and recovers true matches under finite-sample margin conditions. Empirically it outperformed decoder-vector and LLM-based baselines and captured subtle functional distinctions between related features, and it compressed large feature circuits into interpretable supernodes automatically. The limitation is that this is interpretability tooling: the paper demonstrates better feature matching and circuit compression, not that downstream interpretability claims become more accurate.