Objectives  Aiming at solving the problem that the representation of level of detail (LOD) for existing buildings is mainly external and seldom involves the internal space objects, a conceptual model of three-dimensional (3D) LOD for buildings with interior space structure is proposed.

  Methods  The conceptual model is divided into seven LOD levels: LOD0-LOD6, and the LOD consists of footprint, 3D box model, 3D floor model without sides, 3D floor model, 3D room model to 3D room model with semantic information such as doors and windows. The spatial details become gradually refined, which enriches the theory of LOD for building interior space. In order to create LOD models, a LOD generation method based on boundary operator and co-boundary operator of cell complex chain is proposed. The method introduces three concepts of cell, cell complex and complex chain from algebraic topology, and LOD is expressed by cell and cell complex. On the basis of LOD6, boundary operator and co-boundary operator are used to generate other LOD models with coarse spatial granularity.

  Results  The research shows that the proposed LODs can meet the needs of outdoor and indoor multiple detail representation, and the boundary operator and the co-boundary operator can convert LOD6 into coarse LODs.

  Conclusions  The research provides a new method to create 3D LOD of buildings with interior space structure for 3D city model.