3DCity-LLM: Empowering Multi-modality Large Language Models for 3D City-scale Perception and Understanding

Fuente: arXiv
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Main Authors: Chen, Yiping, Li, Jinpeng, Ke, Wenyu, Luo, Yang, Ouyang, Jie, He, Zhongjie, Liu, Li, Fan, Hongchao, Wu, Hao
Format: Preprint
Published: 2026
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author Chen, Yiping
Li, Jinpeng
Ke, Wenyu
Luo, Yang
Ouyang, Jie
He, Zhongjie
Liu, Li
Fan, Hongchao
Wu, Hao
author_facet Chen, Yiping
Li, Jinpeng
Ke, Wenyu
Luo, Yang
Ouyang, Jie
He, Zhongjie
Liu, Li
Fan, Hongchao
Wu, Hao
contents While multi-modality large language models excel in object-centric or indoor scenarios, scaling them to 3D city-scale environments remains a formidable challenge. To bridge this gap, we propose 3DCity-LLM, a unified framework designed for 3D city-scale vision-language perception and understanding. 3DCity-LLM employs a coarse-to-fine feature encoding strategy comprising three parallel branches for target object, inter-object relationship, and global scene. To facilitate large-scale training, we introduce 3DCity-LLM-1.2M dataset that comprises approximately 1.2 million high-quality samples across seven representative task categories, ranging from fine-grained object analysis to multi-faceted scene planning. This strictly quality-controlled dataset integrates explicit 3D numerical information and diverse user-oriented simulations, enriching the question-answering diversity and realism of urban scenarios. Furthermore, we apply a multi-dimensional protocol based on text-similarity metrics and LLM-based semantic assessment to ensure faithful and comprehensive evaluations for all methods. Extensive experiments on two benchmarks demonstrate that 3DCity-LLM significantly outperforms existing state-of-the-art methods, offering a promising and meaningful direction for advancing spatial reasoning and urban intelligence. The source code and dataset are available at https://github.com/SYSU-3DSTAILab/3D-City-LLM.
format Preprint
id arxiv_https___arxiv_org_abs_2603_23447
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle 3DCity-LLM: Empowering Multi-modality Large Language Models for 3D City-scale Perception and Understanding
Chen, Yiping
Li, Jinpeng
Ke, Wenyu
Luo, Yang
Ouyang, Jie
He, Zhongjie
Liu, Li
Fan, Hongchao
Wu, Hao
Computer Vision and Pattern Recognition
Artificial Intelligence
I.2.10
While multi-modality large language models excel in object-centric or indoor scenarios, scaling them to 3D city-scale environments remains a formidable challenge. To bridge this gap, we propose 3DCity-LLM, a unified framework designed for 3D city-scale vision-language perception and understanding. 3DCity-LLM employs a coarse-to-fine feature encoding strategy comprising three parallel branches for target object, inter-object relationship, and global scene. To facilitate large-scale training, we introduce 3DCity-LLM-1.2M dataset that comprises approximately 1.2 million high-quality samples across seven representative task categories, ranging from fine-grained object analysis to multi-faceted scene planning. This strictly quality-controlled dataset integrates explicit 3D numerical information and diverse user-oriented simulations, enriching the question-answering diversity and realism of urban scenarios. Furthermore, we apply a multi-dimensional protocol based on text-similarity metrics and LLM-based semantic assessment to ensure faithful and comprehensive evaluations for all methods. Extensive experiments on two benchmarks demonstrate that 3DCity-LLM significantly outperforms existing state-of-the-art methods, offering a promising and meaningful direction for advancing spatial reasoning and urban intelligence. The source code and dataset are available at https://github.com/SYSU-3DSTAILab/3D-City-LLM.
title 3DCity-LLM: Empowering Multi-modality Large Language Models for 3D City-scale Perception and Understanding
topic Computer Vision and Pattern Recognition
Artificial Intelligence
I.2.10
url https://arxiv.org/abs/2603.23447