scholarly journals Experiments on the Virtual City: Three-Dimensional Reconfigurations of Missing, Never Realized or Destroyed Urban Areas

2011 ◽  
Author(s):  
Gian Marco Girgenti ◽  
Mauro Filippi ◽  
Federica Marrone
Keyword(s):  
Urban Areas ◽  
Three Dimensional ◽  
Virtual City

scholarly journals Dip angles of active faults from the surface to the seismogenic zone inferred from a 2D numerical analysis of visco-elasto-plastic models: a case study for the Osaka Plain

2021 ◽  
Vol 73 (1) ◽  
Author(s):  
Hayami Nishiwaki ◽  
Takamoto Okudaira ◽  
Kazuhiko Ishii ◽  
Muneki Mitamura
Keyword(s):  
Urban Areas ◽  
Active Faults ◽  
Three Dimensional ◽  
Seismogenic Zone ◽  
Earthquake Ground Motion ◽  
Convex Curve ◽  
Seismic Reflection Profile ◽  
Geological Structures ◽  
Dimensional Distribution ◽  
Dip Angle

AbstractThe geometries (i.e., dip angles) of active faults from the surface to the seismogenic zone are the most important factors used to evaluate earthquake ground motion, which is crucial for seismic hazard assessments in urban areas. In Osaka, a metropolitan city in Japan, there are several active faults (e.g., the Uemachi and Ikoma faults), which are inferred from the topography, the attitude of active faults in surface trenches, the seismic reflection profile at shallow depths (less than 2 km), and the three-dimensional distribution of the Quaternary sedimentary layers. The Uemachi and Ikoma faults are N–S-striking fault systems with total lengths of 42 km and 38 km, respectively, with the former being located ~ 12 km west of the latter; however, the geometries of each of the active faults within the seismogenic zone are not clear. In this study, to examine the geometries of the Uemachi and Ikoma faults from the surface to the seismogenic zone, we analyze the development of the geological structures of sedimentary layers based on numerical simulations of a two-dimensional visco-elasto-plastic body under a horizontal compressive stress field, including preexisting high-strained weak zones (i.e., faults) and surface sedimentation processes, and evaluate the relationship between the observed geological structures of the Quaternary sediments (i.e., the Osaka Group) in the Osaka Plain and the model results. As a result, we propose geometries of the Uemachi and Ikoma faults from the surface to the seismogenic zone. When the friction coefficient of the faults is ~ 0.5, the dip angles of the Uemachi and Ikoma faults near the surface are ~ 30°–40° and the Uemachi fault has a downward convex curve at the bottom of the seismogenic zone, but does not converge to the Ikoma fault. Based on the analysis in this study, the dip angle of the Uemachi fault zone is estimated to be approximately 30°–40°, which is lower than that estimated in the previous studies. If the active fault has a low angle, the width of the fault plane is long, and thus the estimated seismic moment will be large.

Tunnel performance during the Puebla-Mexico 19 September 2017 earthquake

2020 ◽  
Vol 36 (2_suppl) ◽  
pp. 288-313
Author(s):  
Juan M Mayoral ◽  
Gilberto Mosqueda ◽  
Daniel De La Rosa ◽  
Mauricio Alcaraz
Keyword(s):  
Mexico City ◽  
Seismic Performance ◽  
Urban Areas ◽  
Numerical Study ◽  
Three Dimensional ◽  
Frequency Content ◽  
Seismic Performance Evaluation ◽  
Ground Deformations ◽  
Under Construction ◽  
Observed Damage

Seismic performance of tunnels during earthquakes in densely populated areas requires assessing complex interactions with existing infrastructure such as bridges, urban overpasses, and metro stations, including low- to medium-rise buildings. This article presents the numerical study of an instrumented tunnel, currently under construction on stiff soils, located in the western part of Mexico City, during the Puebla-Mexico 19 September 2017 earthquake. Three-dimensional finite difference models were developed using the software FLAC3D. Initially, the static response of the tunnel was evaluated accounting for the excavation technique. Then, the seismic performance evaluation of the tunnel was carried out, computing ground deformations and factors of safety, considering soil nonlinearities. Good agreement was observed between predicted and observed damage during post-event site observations. Once the soundness of the numerical model was established, a numerical study was undertaken to investigate the effect of frequency content in tunnel-induced ground motion incoherence for tunnels built in cemented stiff soils. A series of strong ground motions recorded during normal and subduction events were used in the simulations, considering a return period of 250 years, as recommended in the Mexico City building code. From the results, it was concluded that the tunnel presence leads to important frequency content modification in the tunnel surroundings which can affect low- to mid-rise stiff structures located nearby. This important finding must be taken into account when assessing the seismic risk in highly populated urban areas, such as Mexico City.

Wind tunnel investigation on the retention of air pollutants in three-dimensional recirculation zones in urban areas

2007 ◽  
Vol 41 (23) ◽  
pp. 4949-4961 ◽  
Author(s):  
Marcos Sebastião de Paula Gomes ◽  
André Augusto Isnard ◽  
José Maurício do Carmo Pinto
Keyword(s):  
Wind Tunnel ◽  
Urban Areas ◽  
Air Pollutants ◽  
Three Dimensional ◽  
Recirculation Zones

scholarly journals Automatic Extraction of Grasses and Individual Trees in Urban Areas Based on Airborne Hyperspectral and LiDAR Data

2020 ◽  
Vol 12 (17) ◽  
pp. 2725
Author(s):  
Qixia Man ◽  
Pinliang Dong ◽  
Xinming Yang ◽  
Quanyuan Wu ◽  
Rongqing Han
Keyword(s):  
Urban Areas ◽  
Three Dimensional ◽  
Hyperspectral Data ◽  
Classification Method ◽  
Urban Vegetation ◽  
Individual Tree ◽  
Cloud Data ◽  
Random Forest Classification ◽  
The Individual ◽  
Individual Trees

Urban vegetation extraction is very important for urban biodiversity assessment and protection. However, due to the diversity of vegetation types and vertical structure, it is still challenging to extract vertical information of urban vegetation accurately with single remotely sensed data. Airborne light detection and ranging (LiDAR) can provide elevation information with high-precision, whereas hyperspectral data can provide abundant spectral information on ground objects. The complementary advantages of LiDAR and hyperspectral data could extract urban vegetation much more accurately. Therefore, a three-dimensional (3D) vegetation extraction workflow is proposed to extract urban grasses and trees at individual tree level in urban areas using airborne LiDAR and hyperspectral data. The specific steps are as follows: (1) airborne hyperspectral and LiDAR data were processed to extract spectral and elevation parameters, (2) random forest classification method and object-based classification method were used to extract the two-dimensional distribution map of urban vegetation, (3) individual tree segmentation was conducted on a canopy height model (CHM) and point cloud data separately to obtain three-dimensional characteristics of urban trees, and (4) the spatial distribution of urban vegetation and the individual tree delineation were assessed by validation samples and manual delineation results. The results showed that (1) both the random forest classification method and object-based classification method could extract urban vegetation accurately, with accuracies above 99%; (2) the watershed segmentation method based on the CHM could extract individual trees correctly, except for the small trees and the large tree groups; and (3) the individual tree segmentation based on point cloud data could delineate individual trees in three-dimensional space, which is much better than CHM segmentation as it can preserve the understory trees. All the results suggest that two- and three-dimensional urban vegetation extraction could play a significant role in spatial layout optimization and scientific management of urban vegetation.

scholarly journals EXTRACTION AND VISUALIZATION OF 3D BUILDING MODELS IN URBAN AREAS FOR FLOOD SIMULATION

2019 ◽  
Vol XLII-2/W11 ◽  
pp. 669-673 ◽  
Author(s):  
C. E. Kilsedar ◽  
F. Fissore ◽  
F. Pirotti ◽  
M. A. Brovelli
Keyword(s):  
Urban Areas ◽  
Three Dimensional ◽  
Decision Makers ◽  
Three Dimensions ◽  
Adaptation Measures ◽  
Flood Simulation ◽  
Domain Experts ◽  
Effective Strategies ◽  
Web Map ◽  
Building Models

<p><strong>Abstract.</strong> Floods pose a risk that is likely to worsen in the future due to climate change. Therefore, it is essential that decision makers and domain experts have the tools to evaluate the effects of floods. We developed a tool that visualizes the earth and buildings in three dimensions to simulate floods so that effective strategies can be developed to enhance resilience and mitigate the effects of floods. We opted to use open standards and free and open source software (FOSS) for Web to maximize interoperability, replicability, reusability, and accessibility. As a result of the literature review, we decided to use CityGML and CesiumJS for three-dimensional geospatial data visualization. However, as CityGML data is not available for the cities that our project focuses on, we developed software called shp2city that converts Esri shapefile to CityGML data in LOD1 or LOD2. Moreover, as CityGML data cannot be immediately used with CesiumJS, we used 3DCityDB to store, represent, and manage the CityGML data; 3DCityDB Importer/Exporter to export the CityGML data in KML/COLLADA/glTF format to be used within the 3DCityDB Web-Map-Client that is based on CesiumJS for visualization. Finally, we simulated floods to aid in the informed decision-making process regarding adaptation measures and mitigation of flooding effects.</p>

scholarly journals Evaluation of Infiltration Rainwater Drainage (IRD) System with Fully 3-D Numerical Simulation Approach

2021 ◽  
Vol 11 (19) ◽  
pp. 9144
Author(s):  
Jungkyu Ahn ◽  
Seongil Yeom ◽  
Sungwon Park ◽  
Thi Hoang Thao Nguyen
Keyword(s):  
Water Scarcity ◽  
Surface Runoff ◽  
Urban Areas ◽  
Model Simulation ◽  
Three Dimensional ◽  
Lag Time ◽  
Prototype Model ◽  
Scaled Model ◽  
Runoff Decrease ◽  
Peak Runoff

Water scarcity can mean scarcity in availability due to physical shortage, or scarcity in access due to the failure of institutions to ensure a continuously regular supply or due to a lack of adequate infrastructure. Water scarcity will be exacerbated as rapidly growing urban areas place heavy pressure on water resources. To solve these problems, various solutions have been applied, but a fundamental solution has not been applied. Recently, a researched and developed infiltration rainwater drainage (IRD) system is being applied with consideration of its applicability. In this study, features of surface runoff and infiltration according to various flow patterns were analyzed using a three-dimensional CFD (Computational Fluid Dynamics) model for calculating water flow in the IRD system. To estimate the optimal setup, a permeability test and scaled model simulation were performed. The runoff characteristics of the IRD system with respect to rainfall intensity and duration were analyzed with dimensionless variables. With the prototype model, the drainage characteristics of the IRD system were analyzed over time using the hydrological curves. From the simulated results, it was found that the IRD system analyzed in this study was appropriate in the field by comparative analysis with the existing system based on peak runoff, internal storage, and lag time. Therefore, by applying the IRD system in the future, it is expected that the IRD has benefits, such as delayed lag time, surface runoff decrease, and an attenuation of the peak runoff.

Visiting Tourist Landmarks in Virtual Reality Systems by Real-Walking

2010 ◽  
pp. 180-193 ◽  
Author(s):  
F. Steinicke ◽  
G. Bruder ◽  
J. Jerald ◽  
H. Frenz
Keyword(s):  
Virtual Reality ◽  
Virtual Environments ◽  
Virtual Environment ◽  
User Interfaces ◽  
Large Scale ◽  
Three Dimensional ◽  
Interaction Space ◽  
Immersive Virtual Environments ◽  
Redirected Walking ◽  
Virtual City

In recent years virtual environments (VEs) have become more and more popular and widespread due to the requirements of numerous application areas in particular in the 3D city visualization domain. Virtual reality (VR) systems, which make use of tracking technologies and stereoscopic projections of three-dimensional synthetic worlds, support better exploration of complex datasets. However, due to the limited interaction space usually provided by the range of the tracking sensors, users can explore only a portion of the virtual environment (VE). Redirected walking allows users to walk through large-scale immersive virtual environments (IVEs) such as virtual city models, while physically remaining in a reasonably small workspace by intentionally injecting scene motion into the IVE. With redirected walking users are guided on physical paths that may differ from the paths they perceive in the virtual world. The authors have conducted experiments in order to quantify how much humans can unknowingly be redirected. In this chapter they present the results of this study and the implications for virtual locomotion user interfaces that allow users to view arbitrary real world locations, before the users actually travel there in a natural environment.

scholarly journals Micrometeorological Modeling of Radiative and Convective Effects with a Building-Resolving Code

2011 ◽  
Vol 50 (8) ◽  
pp. 1713-1724 ◽  
Author(s):  
Yongfeng Qu ◽  
Maya Milliez ◽  
Luc Musson-Genon ◽  
Bertrand Carissimo
Keyword(s):  
Urban Areas ◽  
Fluid Dynamic ◽  
Three Dimensional ◽  
Pollutant Dispersion ◽  
Urban Setting ◽  
Dynamical Model ◽  
Neutral Atmosphere ◽  
Atmospheric Flow ◽  
Ongoing Work ◽  
The One

AbstractIn many micrometeorological studies with computational fluid dynamics, building-resolving models usually assume a neutral atmosphere. Nevertheless, urban radiative transfers play an important role because of their influence on the energy budget. To take into account atmospheric radiation and the thermal effects of the buildings in simulations of atmospheric flow and pollutant dispersion in urban areas, a three-dimensional (3D) atmospheric radiative scheme has been developed in the atmospheric module of the Code_Saturne 3D computational fluid dynamic model. On the basis of the discrete ordinate method, the radiative model solves the radiative transfer equation in a semitransparent medium for complex geometries. The spatial mesh discretization is the same as the one used for the dynamics. This paper describes ongoing work with the development of this model. The radiative scheme was previously validated with idealized cases. Here, results of the full coupling of the radiative and thermal schemes with the 3D dynamical model are presented and are compared with measurements from the Mock Urban Setting Test (MUST) and with simpler modeling approaches found in the literature. The model is able to globally reproduce the differences in diurnal evolution of the surface temperatures of the different walls and roof. The inhomogeneous wall temperature is only seen when using the 3D dynamical model for the convective scheme.

scholarly journals Tropospheric Delay Correction Based on a Three-Dimensional Joint Model for InSAR

2019 ◽  
Vol 11 (21) ◽  
pp. 2542
Author(s):  
Huaping Xu ◽  
Yao Luo ◽  
Bo Yang ◽  
Zhaohong Li ◽  
Wei Liu
Keyword(s):  
Urban Areas ◽  
Surface Deformation ◽  
Three Dimensional ◽  
Joint Model ◽  
Three Dimensions ◽  
Superior Performance ◽  
Tropospheric Delay ◽  
Natural Scenes ◽  
Delay Correction ◽  
Tropospheric Delays

Tropospheric delays in spaceborne Interferometric Synthetic Aperture Radar (InSAR) can contaminate the measurement of small amplitude earth surface deformation. In this paper, a novel TXY-correlated method is proposed, where the main tropospheric delay components are jointly modeled in three dimensions, and then the long-scale and topography-correlated tropospheric delay components are corrected simultaneously. Moreover, the strategies of scale filtering and alternative iteration are employed to accurately retrieve all components of the joint model. Both the TXY-correlated method and the conventional phase-based methods are tested with a total of 25 TerraSAR-X/TanDEM-X images collected over the Chaobai River site and the Renhe Town of Beijing Shunyi District, where natural scenes and man-made targets are contained. A higher correction rate of tropospheric delays and a greater reduction in spatio-temporal standard deviations of time series displacement are observed after delay correction by the TXY-correlated method in both non-urban and urban areas, which demonstrate the superior performance of the proposed method.

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