The construction of a twin model with high fidelity, real-time mapping and scalability is the foundation for realizing digital twin in underground space. Given the large size and complexity of digital twin geometric model data in underground space, it is of practical significance to study lightweighting techniques to speed up transmission and enhance rendering performance. Therefore, this paper provides a comprehensive review of current research on digital twin modeling of underground space, aiming to clarify the elements, methods, and technical directions for constructing the twin model. Firstly, the conceptual framework of digital twin modeling in underground space is proposed and the components of virtual model are elaborated in detail. Current modeling methods and tools for geological bodies, machines and structural bodies are reviewed. Finally, existing lightweighting methods for geometric modeling and their advantages and disadvantages are summarized, and future research directions for digital twin modeling and lightweighting methods are proposed.

中文翻译：

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地下空间数字孪生建模和轻量级几何建模技术的进展


构建高保真、实时测图、可扩展的孪生模型是实现地下空间数字孪生的基础。鉴于地下空间数字孪生几何模型数据规模大、复杂，研究轻量化技术以加快传输速度、增强渲染性能具有现实意义。因此，本文对地下空间数字孪生模型的研究现状进行了全面回顾，旨在明确地下空间数字孪生模型构建的要素、方法和技术方向。首先提出了地下空间数字孪生建模的概念框架，详细阐述了虚拟模型的组成部分。回顾了当前地质体、机器和结构体的建模方法和工具。最后，总结了现有的几何建模轻量化方法及其优缺点，并提出了数字孪生建模和轻量化方法的未来研究方向。