#158 | Presentation of VRVis' Integrated Simulations Group
Presentation of VRVis' Integrated Simulations Group
31.10.2019, starting 15:00
Interactive Visualization of Flood and Heavy Rain Simulations
We present a real-time technique to visualize large-scale adaptive height fields with C1-continuous surface reconstruction. Grid-based shallow water simulation is an indispensable tool for interactive flood management applications. Height fields defined on adaptive grids are often the only viable option to store and process the massive simulation data. Their visualization requires the reconstruction of a continuous surface from the spatially discrete simulation data. For regular grids, fast linear and cubic interpolation are commonly used for surface reconstruction. For adaptive grids, however, there exists no higher-order interpolation technique fast enough for interactive applications. Our proposed technique bridges the gap between fast linear and expensive higher-order interpolation for adaptive surface reconstruction. During reconstruction, no matter if regular or adaptive, discretization and interpolation artifacts can occur, which domain experts consider misleading and unaesthetic. We take into account boundary conditions to eliminate these artifacts, which include water climbing uphill, diving towards walls, and leaking through thin objects. We apply realistic water shading with visual cues for depth perception and add waves and foam synthesized from the simulation data to emphasize flow directions. The versatility and performance of our technique are demonstrated in various real-world scenarios. A survey conducted with domain experts of different backgrounds and concerned citizens proves the usefulness and effectiveness of our technique.
High-Resolution Flood Risk Mapping at the Country Scale
Accurate and detailed flood hazard maps are of major importance for regional-development planning, evacuation routes in case of emergency, reinsurance products, etc. In this talk, we focus on the hydraulic part of such a project, i.e. the derivation of inundated areas from estimated flood discharges for given return periods. Based on a river network including prescribed design hydrograph waves, the presented method automatically derives instationary boundary conditions for any given simulation domain. The instationary simulation ensures that defense structures such as retention basins are taken into account. Moreover, our approach overcomes difficulties associated at river confluences, where prescribed design flood wave discharges have to be ensured by a mass-conserving physical representation of river flow. Recent advances in numerical and computational methods render two-dimensional flood simulations with resolutions of a few metres at the country scale feasible. The high resolution results in flood risk maps as accurate as detailed local flood maps, thus highlighting the efficiency of the approach.