The desired outcome for urban digital twins is an automatically generated detailed 3D model of a building from aerial imagery, footprints, LiDAR, or a fusion of these. Such 3D models have applications in architecture, civil engineering, urban planning, construction, real estate, GIS, and many others. Further, the visualization of large-scale data in conjunction with the generated 3D models is often a recurring and resource-intensive task. However, a completely automated end-to-end workflow is complex, requiring many steps to achieve a high-quality visualization. Methods for building reconstruction approaches have come a long way from previously manual approaches to semi-automatic or automatic approaches. The next step after reconstructing buildings is visualizing the buildings and their context. Advances in real-time rendering using game engines have enabled the extension of building reconstruction methods to procedurally generated context generation. This paper aims to complement existing methods of 3D building generation. First, we present a literature review covering different options for procedurally generated context generation and visualization methods in-depth, focusing on workflows and data pipelines. Next, we present a semi-automated workflow that extends the building reconstruction pipeline to include procedural context generation (terrain and vegetation) using Unreal Engine and, finally, the integration of various types of large-scale urban analysis data for visualization. We conclude with a series of challenges faced in achieving such pipelines and the limitations of the current approach. The steps for a complete, end-to-end solution involve developing robust systems for building detection, rooftop recognition, and geometry generation and importing and visualizing data in the same 3D environment.

翻译：城市数字孪生的理想成果是通过航空影像、足迹数据、激光雷达或其融合结果自动生成建筑的详细三维模型。此类三维模型在建筑、土木工程、城市规划、施工、房地产、地理信息系统及其他领域具有广泛应用。此外，将大规模数据与生成的三维模型相结合进行可视化，通常是一项重复且资源密集型的任务。然而，完全自动化的端到端工作流程十分复杂，需要多个步骤才能实现高质量的可视化效果。建筑重建方法已从早期的手动方法发展为半自动或全自动方法。建筑重建之后的下一个步骤是建筑及其环境的三维可视化。基于游戏引擎的实时渲染技术进展，使得建筑重建方法可扩展至程序化环境生成。本文旨在补充现有三维建筑生成方法。首先，我们进行了文献综述，深入探讨了程序化环境生成与可视化方法的多种方案，重点关注工作流程与数据管道。其次，我们提出了一种半自动化工作流程，该流程扩展了建筑重建管道，借助虚幻引擎实现了程序化环境（地形与植被）生成，并最终整合了多种大规模城市分析数据以实现可视化。最后，我们总结了实现此类管道所面临的系列挑战及当前方法的局限性。完整的端到端解决方案涉及构建鲁棒的建筑检测、屋顶识别与几何生成系统，并在同一三维环境中完成数据导入与可视化。