Spatial-MLLM: Boosting MLLM Capabilities in Visual-based Spatial Intelligence

Fuente: arXiv
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Auteurs principaux: Wu, Diankun, Liu, Fangfu, Hung, Yi-Hsin, Duan, Yueqi
Format: Preprint
Publié: 2025
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author Wu, Diankun
Liu, Fangfu
Hung, Yi-Hsin
Duan, Yueqi
author_facet Wu, Diankun
Liu, Fangfu
Hung, Yi-Hsin
Duan, Yueqi
contents Recent advancements in Multimodal Large Language Models (MLLMs) have significantly enhanced performance on 2D visual tasks. However, improving their spatial intelligence remains a challenge. Existing 3D MLLMs always rely on additional 3D or 2.5D data to incorporate spatial awareness, restricting their utility in scenarios with only 2D inputs, such as images or videos. In this paper, we present Spatial-MLLM, a novel framework for visual-based spatial reasoning from purely 2D observations. Unlike conventional video MLLMs which rely on CLIP-based visual encoders optimized for semantic understanding, our key insight is to unleash the strong structure prior from the feed-forward visual geometry foundation model. Specifically, we propose a dual-encoder architecture: a pretrained 2D visual encoder to extract semantic features, and a 3D spatial encoder-initialized from the backbone of the visual geometry model-to extract 3D structure features. A connector then integrates both features into unified visual tokens for enhanced spatial understanding. Furthermore, we propose a space-aware frame sampling strategy at inference time, which selects the spatially informative frames of a video sequence, ensuring that even under limited token length, the model focuses on frames critical for spatial reasoning. Beyond architecture improvements, we construct a training dataset from multiple sources and train the model on it using supervised fine-tuning and GRPO. Extensive experiments on various real-world datasets demonstrate that Spatial-MLLM achieves state-of-the-art performance in a wide range of visual-based spatial understanding and reasoning tasks. Project page: https://diankun-wu.github.io/Spatial-MLLM/.
format Preprint
id arxiv_https___arxiv_org_abs_2505_23747
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Spatial-MLLM: Boosting MLLM Capabilities in Visual-based Spatial Intelligence
Wu, Diankun
Liu, Fangfu
Hung, Yi-Hsin
Duan, Yueqi
Computer Vision and Pattern Recognition
Artificial Intelligence
Machine Learning
I.2.6; I.2
Recent advancements in Multimodal Large Language Models (MLLMs) have significantly enhanced performance on 2D visual tasks. However, improving their spatial intelligence remains a challenge. Existing 3D MLLMs always rely on additional 3D or 2.5D data to incorporate spatial awareness, restricting their utility in scenarios with only 2D inputs, such as images or videos. In this paper, we present Spatial-MLLM, a novel framework for visual-based spatial reasoning from purely 2D observations. Unlike conventional video MLLMs which rely on CLIP-based visual encoders optimized for semantic understanding, our key insight is to unleash the strong structure prior from the feed-forward visual geometry foundation model. Specifically, we propose a dual-encoder architecture: a pretrained 2D visual encoder to extract semantic features, and a 3D spatial encoder-initialized from the backbone of the visual geometry model-to extract 3D structure features. A connector then integrates both features into unified visual tokens for enhanced spatial understanding. Furthermore, we propose a space-aware frame sampling strategy at inference time, which selects the spatially informative frames of a video sequence, ensuring that even under limited token length, the model focuses on frames critical for spatial reasoning. Beyond architecture improvements, we construct a training dataset from multiple sources and train the model on it using supervised fine-tuning and GRPO. Extensive experiments on various real-world datasets demonstrate that Spatial-MLLM achieves state-of-the-art performance in a wide range of visual-based spatial understanding and reasoning tasks. Project page: https://diankun-wu.github.io/Spatial-MLLM/.
title Spatial-MLLM: Boosting MLLM Capabilities in Visual-based Spatial Intelligence
topic Computer Vision and Pattern Recognition
Artificial Intelligence
Machine Learning
I.2.6; I.2
url https://arxiv.org/abs/2505.23747