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Autori principali: Zhang, Jian, Zhou, Shijie, Liu, Bangya, Kadambi, Achuta, Fan, Zhiwen
Natura: Preprint
Pubblicazione: 2026
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Accesso online:https://arxiv.org/abs/2603.27437
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author Zhang, Jian
Zhou, Shijie
Liu, Bangya
Kadambi, Achuta
Fan, Zhiwen
author_facet Zhang, Jian
Zhou, Shijie
Liu, Bangya
Kadambi, Achuta
Fan, Zhiwen
contents Large vision-language models (VLMs) still struggle with reliable 3D spatial reasoning, a core capability for embodied and physical AI systems. This limitation arises from their inability to capture fine-grained 3D geometry and spatial relationships. While recent efforts have introduced multi-view geometry transformers into VLMs, they typically fuse only the deep-layer features from vision and geometry encoders, discarding rich hierarchical signals and creating a fundamental bottleneck for spatial understanding. To overcome this, we propose SpatialStack, a general hierarchical fusion framework that progressively aligns vision, geometry, and language representations across the model hierarchy. Moving beyond conventional late-stage vision-geometry fusion, SpatialStack stacks and synchronizes multi-level geometric features with the language backbone, enabling the model to capture both local geometric precision and global contextual semantics. Building upon this framework, we develop VLM-SpatialStack, a model that achieves state-of-the-art performance on multiple 3D spatial reasoning benchmarks. Extensive experiments and ablations demonstrate that our multi-level fusion strategy consistently enhances 3D understanding and generalizes robustly across diverse spatial reasoning tasks, establishing SpatialStack as an effective and extensible design paradigm for vision-language-geometry integration in next-generation multimodal physical AI systems.
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publishDate 2026
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spellingShingle SpatialStack: Layered Geometry-Language Fusion for 3D VLM Spatial Reasoning
Zhang, Jian
Zhou, Shijie
Liu, Bangya
Kadambi, Achuta
Fan, Zhiwen
Computer Vision and Pattern Recognition
Large vision-language models (VLMs) still struggle with reliable 3D spatial reasoning, a core capability for embodied and physical AI systems. This limitation arises from their inability to capture fine-grained 3D geometry and spatial relationships. While recent efforts have introduced multi-view geometry transformers into VLMs, they typically fuse only the deep-layer features from vision and geometry encoders, discarding rich hierarchical signals and creating a fundamental bottleneck for spatial understanding. To overcome this, we propose SpatialStack, a general hierarchical fusion framework that progressively aligns vision, geometry, and language representations across the model hierarchy. Moving beyond conventional late-stage vision-geometry fusion, SpatialStack stacks and synchronizes multi-level geometric features with the language backbone, enabling the model to capture both local geometric precision and global contextual semantics. Building upon this framework, we develop VLM-SpatialStack, a model that achieves state-of-the-art performance on multiple 3D spatial reasoning benchmarks. Extensive experiments and ablations demonstrate that our multi-level fusion strategy consistently enhances 3D understanding and generalizes robustly across diverse spatial reasoning tasks, establishing SpatialStack as an effective and extensible design paradigm for vision-language-geometry integration in next-generation multimodal physical AI systems.
title SpatialStack: Layered Geometry-Language Fusion for 3D VLM Spatial Reasoning
topic Computer Vision and Pattern Recognition
url https://arxiv.org/abs/2603.27437