Towards automatic reconstruction of 3D city models tailored for urban flow simulations

Abstract

In the computational fluid dynamics simulation workflow, the geometry preparation step is often regarded as a tedious, time-consuming task. Many practitioners consider it one of the main bottlenecks in the simulation process. The more complex the geometry, the longer the necessary work, meaning this issue is amplified for urban flow simulations that cover large areas with complex building geometries. To address the issue of geometry preparation, we propose a workflow for automatically reconstructing simulation-ready 3D city models. The workflow combines 2D geographical datasets (e.g., cadastral data, topographic datasets) and aerial point cloud-based elevation data to reconstruct terrain, buildings, and imprint surface layers like water, low vegetation, and roads. Imprinted surface layers serve as different roughness surfaces for modeling the atmospheric boundary layer. Furthermore, the workflow is capable of automatically defining the influence region and domain size according to best practice guidelines. The resulting geometry aims to be error-free: without gaps, self-intersections, and non-manifold edges. The workflow was implemented into an open-source framework using modern, robust, and state-of-the-art libraries with the intent to be used for further developments. Our approach limits the geometry generation step to the order of hours (including input data retrieval and preparation), producing geometries that can be directly used for computational grid generation without additional preparation. The reconstruction done by the algorithm can last from a few seconds to a few minutes, depending on the size of the input data. We obtained and prepared the input data for our verification study in about 2 hours, while the reconstruction process lasted 1 minute. The unstructured computational meshes we created in an automatic mesh generator show satisfactory quality indicators and the subsequent numerical simulation exhibits good convergence behavior with the grid convergence index of observed variables less than 5%.

Automatic Reconstruction of 3D Models from 2D Drawings: A State-of-the-Art Review

“…Overall, articles tend to focus on a narrow scope of building components, depending on the research's objective; for example, for 3D visualisation and walkthroughs, only visual and geometric elements are considered, and thus, spaces and MEP are often neglected. However, in the last two years, there have been two studies on the automatic reconstruction of MEP structures [61,74] that suggest that there are methodologies in development to retrieve this building information.…”

Integration of GIS and CAD data to perform interactive preliminary environmental analyses at district scale

“…Nevertheless, depending on the type of input data, different strategies were implemented to check and repair geometry issues for the successive environmental simulation analysis. A description of such issues, and some remedies are described for example in (Donkers et al, 2016;Padjen et al, 2022). Eventually, the GIS data must be translated to a local coordinate system (this is the default case in Rhinoceros/Grasshopper), before the "new" building model can be integrated.…”

Simulation-Based Engineering of Heterogeneous Collaborative Systems—A Novel Conceptual Framework

“…Urban planning and growth estimation effects on urban service delivery represent the mainstream of urban growth simulations [40]. Joined with urban flow management [41,42], the dimensionality of the simulation model emerges.…”