[2603.28887] OccSim: Multi-kilometer Simulation with Long-horizon Occupancy World Models

Computer Science > Computer Vision and Pattern Recognition arXiv:2603.28887 (cs) [Submitted on 30 Mar 2026] Title:OccSim: Multi-kilometer Simulation with Long-horizon Occupancy World Models Authors:Tianran Liu, Shengwen Zhao, Mozhgan Pourkeshavarz, Weican Li, Nicholas Rhinehart View a PDF of the paper titled OccSim: Multi-kilometer Simulation with Long-horizon Occupancy World Models, by Tianran Liu and 4 other authors View PDF HTML (experimental) Abstract:Data-driven autonomous driving simulation has long been constrained by its heavy reliance on pre-recorded driving logs or spatial priors, such as HD maps. This fundamental dependency severely limits scalability, restricting open-ended generation capabilities to the finite scale of existing collected datasets. To break this bottleneck, we present OccSim, the first occupancy world model-driven 3D simulator. OccSim obviates the requirement for continuous logs or HD maps; conditioned only on a single initial frame and a sequence of future ego-actions, it can stably generate over 3,000 continuous frames, enabling the continuous construction of large-scale 3D occupancy maps spanning over 4 kilometers for simulation. This represents an >80x improvement in stable generation length over previous state-of-the-art occupancy world models. OccSim is powered by two modules: W-DiT based static occupancy world model and the Layout Generator. W-DiT handles the ultra-long-horizon generation of static environments by explicitly introducing ...