UBMDP: Urban Building Mesh Decoupling and Polygonization.

With the development of photogrammetry, digital city, and metaverse, the 3-D representation of urban buildings has attracted more and more attention. As the main form of the 3-D urban building model, the triangular mesh model has deficiencies such as high complexity, high-data volume, and low-structural information, which seriously restrict its application in spatial analysis and urban planning. This article proposes a hybrid modeling strategy geared toward the mesh model generated from oblique images to obtain building models that are compact, manifold, watertight, and have certain structural and semantic information. First of all, when the planar region topology graph has been established, a topology decoupling strategy is designed to obtain a set of relatively independent topology subgraphs which form a hierarchical structure. After that, to improve model quality, topology optimization of parallel planes has also been studied systematically. Then, we adopt a divide-and-conquer strategy to perform data-driven and model-driven building modeling for the primary and ancillary structures. Finally, a component-level simple polygon model combination is generated. Experiments prove that the proposed method has excellent visual authenticity, structural completeness advantages, and decent LoD3 ability. As a mesh simplification method, the data is compressed to 0.11%-0.75% in a Hausdorff metric around 0.3 m, which further proves that this method is state-of-the-art.