3维空间数据模型是构建3维空间数据库和3维GIS的基础，有着极为重要的研究意义。为了能更好地表示空间3维对象，提出了一种基于3D-realms的数据模型，它是对基于2D-realms的空间数据模型的3维扩展，并详细给出了该模型的基本定义、语义描述和基于该模型的3维空间对象操作，运用分层的方法可将该模型分为4层：3维几何原语层、3D-realms层、3维基本空间构建要素层和3维基本空间对象层（包括点、线、面和体）。其中，由于每个较低层都是构建较高层中元素的基础，因此可为上层提供支持。实验表明，基于3D-realms的3维空间数据模型不仅能保证拓扑关系的正确性，而且能较好地表示3维空间对象，并能有效地支持3维空间拓扑分析操作。

A 3D spatial data model is the foundation of 3D spatial database and 3D GIS,so it has great significance of research. A 3D spatial data model based on the 3D discrete domain,3D-realms,is introduced in this paper. It is the extension of the 2D realms in the 3D space. The basic definition,semantic description and the spatial operations of this spatial model are presented in this paper. This 3D spatial data model can be divided into four layers: 3D geometric primitives layer,3D-realms layer,basic spatial constructional elements layer and basic spatial objects layer which includes points object,lines object,regions object and bodies object. Each lower layer is the foundation of construction elements of the higher layer and provides supports for it. The 3D spatial data model based on 3D-realms can guarantee the correctness of topological relations,describe 3D spatial objects well and effectively support the 3D spatial topological operations.