SYNBUILD-3D: A large, multi-modal, and semantically rich synthetic dataset of 3D building models at Level of Detail 4

3D building models are critical for applications in architecture, energy simulation, and navigation. Yet, generating accurate and semantically rich 3D buildings automatically remains a major challenge due to the lack of large-scale annotated datasets in the public domain. Inspired by the success of synthetic data in computer vision, we introduce SYNBUILD-3D, a large, diverse, and multi-modal dataset of over 6.2 million synthetic 3D residential buildings at Level of Detail (LOD) 4. In the dataset, each building is represented through three distinct modalities: a semantically enriched 3D wireframe graph at LOD 4 (Modality I), the corresponding floor plan images (Modality II), and a LiDAR-like point cloud sampled from the respective roof surface (Modality III). The semantic annotations for each building wireframe are derived from the corresponding floor plan images and include information on rooms, doors, and windows. Through its tri-modal nature, future work can use SYNBUILD-3D to develop novel generative AI algorithms that automate the creation of 3D building models at LOD 4, subject to predefined floor plan layouts and roof geometries, while enforcing semantic–geometric consistency.