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Main Authors: Liao, Zhimin, Wei, Ping, Zhang, Ruijie, Chen, Shuaijia, Wang, Haoxuan, Ren, Ziyang
Format: Preprint
Published: 2025
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Online Access:https://arxiv.org/abs/2507.09144
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author Liao, Zhimin
Wei, Ping
Zhang, Ruijie
Chen, Shuaijia
Wang, Haoxuan
Ren, Ziyang
author_facet Liao, Zhimin
Wei, Ping
Zhang, Ruijie
Chen, Shuaijia
Wang, Haoxuan
Ren, Ziyang
contents Forecasting the evolution of 3D scenes and generating unseen scenarios via occupancy-based world models offers substantial potential for addressing corner cases in autonomous driving systems. While tokenization has revolutionized image and video generation, efficiently tokenizing complex 3D scenes remains a critical challenge for 3D world models. To address this, we propose $I^{2}$-World, an efficient framework for 4D occupancy forecasting. Our method decouples scene tokenization into intra-scene and inter-scene tokenizers. The intra-scene tokenizer employs a multi-scale residual quantization strategy to hierarchically compress 3D scenes while preserving spatial details. The inter-scene tokenizer residually aggregates temporal dependencies across timesteps. This dual design preserves the compactness of 3D tokenizers while retaining the dynamic expressiveness of 4D tokenizers. Unlike decoder-only GPT-style autoregressive models, $I^{2}$-World adopts an encoder-decoder architecture. The encoder aggregates spatial context from the current scene and predicts a transformation matrix to enable high-level control over scene generation. The decoder, conditioned on this matrix and historical tokens, ensures temporal consistency during generation. Experiments demonstrate that $I^{2}$-World achieves state-of-the-art performance, outperforming existing methods by 25.1\% in mIoU and 36.9\% in IoU for 4D occupancy forecasting while exhibiting exceptional computational efficiency: it requires merely 2.9 GB of training memory and achieves real-time inference at 37.0 FPS. Our code is available on https://github.com/lzzzzzm/II-World.
format Preprint
id arxiv_https___arxiv_org_abs_2507_09144
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle $I^{2}$-World: Intra-Inter Tokenization for Efficient Dynamic 4D Scene Forecasting
Liao, Zhimin
Wei, Ping
Zhang, Ruijie
Chen, Shuaijia
Wang, Haoxuan
Ren, Ziyang
Computer Vision and Pattern Recognition
Forecasting the evolution of 3D scenes and generating unseen scenarios via occupancy-based world models offers substantial potential for addressing corner cases in autonomous driving systems. While tokenization has revolutionized image and video generation, efficiently tokenizing complex 3D scenes remains a critical challenge for 3D world models. To address this, we propose $I^{2}$-World, an efficient framework for 4D occupancy forecasting. Our method decouples scene tokenization into intra-scene and inter-scene tokenizers. The intra-scene tokenizer employs a multi-scale residual quantization strategy to hierarchically compress 3D scenes while preserving spatial details. The inter-scene tokenizer residually aggregates temporal dependencies across timesteps. This dual design preserves the compactness of 3D tokenizers while retaining the dynamic expressiveness of 4D tokenizers. Unlike decoder-only GPT-style autoregressive models, $I^{2}$-World adopts an encoder-decoder architecture. The encoder aggregates spatial context from the current scene and predicts a transformation matrix to enable high-level control over scene generation. The decoder, conditioned on this matrix and historical tokens, ensures temporal consistency during generation. Experiments demonstrate that $I^{2}$-World achieves state-of-the-art performance, outperforming existing methods by 25.1\% in mIoU and 36.9\% in IoU for 4D occupancy forecasting while exhibiting exceptional computational efficiency: it requires merely 2.9 GB of training memory and achieves real-time inference at 37.0 FPS. Our code is available on https://github.com/lzzzzzm/II-World.
title $I^{2}$-World: Intra-Inter Tokenization for Efficient Dynamic 4D Scene Forecasting
topic Computer Vision and Pattern Recognition
url https://arxiv.org/abs/2507.09144