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 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.

scholarly journals How do green areas influence the temperature of cities? Web map to help local decision making about cities and the climate emergency

2021 ◽  
Vol 2 ◽  
pp. 1-6
Author(s):  
Carla Garcia-Lozano ◽  
Anna Peliova ◽  
Josep Sitjar
Keyword(s):  
Urban Areas ◽  
Large Scale ◽  
Decision Makers ◽  
Efficient Manner ◽  
Web Map ◽  
Urban Greenery ◽  
Local Decision ◽  
Local Decision Making ◽  
The City ◽  
Positive Effect

Abstract. The positive effect of urban greenery on the city’s microclimate is well known, as is its ability to reduce the ambient temperature in urban areas. Our results show how the areas with the lowest surface temperature clearly coincide with the vegetated areas in the city of Barcelona. This phenomenon demonstrates the importance of increasing the urban greenery in large compact cities, such as the city of Barcelona, in order to regulate the local temperature and mitigate the effects of global warming on a large scale. The web map presented here can be used as a tool for decision makers to identify the warmest areas in the city of Barcelona and to increase greenery in an efficient manner.

scholarly journals A Learning Approach to Evaluate the Quality of 3D City Models

2019 ◽  
Vol 85 (12) ◽  
pp. 865-878 ◽  
Author(s):  
Oussama Ennafii ◽  
Arnaud Le Bris ◽  
Florent Lafarge ◽  
Clément Mallet
Keyword(s):  
Urban Areas ◽  
Standard Procedure ◽  
Three Dimensional ◽  
Remote Sensing Data ◽  
Automatic Generation ◽  
Building Models ◽  
Training Samples ◽  
High Resolution Images ◽  
The Impact

The automatic generation of three-dimensional (3D) building models from geospatial data is now a standard procedure. An abundance of literature covers the last two decades, and several solutions are now available. However, urban areas are very complex environments. Inevitably, practitioners still have to visually assess, at a city-scale, the correctness of these models and detect frequent reconstruction errors. Such a process relies on experts and is highly time-consuming, with approximately two hours/km 2 per expert. This work proposes an approach for automatically evaluating the quality of 3D building models. Potential errors are compiled in a novel hierarchical and versatile taxonomy. This allows, for the first time, to disentangle fidelity and modeling errors, whatever the level of details of the modeled buildings. The quality of models is predicted using the geometric properties of buildings and, when available, Very High Resolution images and Digital Surface Models. A baseline of handcrafted, yet generic, features is fed into a Random Forest classifier. Both multiclass and multilabel cases are considered: due to the interdependence between classes of errors, it is possible to retrieve all errors at the same time while simply predicting correct and erroneous buildings. The proposed framework was tested on three distinct urban areas in France with more than 3000 buildings. 80%–99% F-score values are attained for the most frequent errors. For scalability purposes, the impact of the urban area composition on the error prediction was also studied, in terms of transferability, generalization, and representativeness of the classifiers. It showed the necessity of multimodal remote sensing data and mixing training samples from various cities to ensure a stability of the detection ratios, even with very limited training set sizes.

scholarly journals SDG-Based Sustainability Assessment Methodology for Innovations in the Field of Urban Surfaces

2020 ◽  
Vol 12 (11) ◽  
pp. 4466 ◽  
Author(s):  
Kristina Henzler ◽  
Stephanie D. Maier ◽  
Michael Jäger ◽  
Rafael Horn
Keyword(s):  
Urban Areas ◽  
Sustainability Assessment ◽  
Methodological Approach ◽  
Innovation Process ◽  
Assessment Method ◽  
Decision Makers ◽  
Three Dimensions ◽  
Potential Contribution ◽  
Economic Dimension

The sustainability of urban surfaces can be enhanced by introducing innovations. An ex-ante assessment of the potential sustainability impacts of innovations in urban areas can provide decision-makers with valuable recommendations for their selection before implementation. This knowledge helps to make the innovation more future-proof. Although a first methodological approach for such an assessment is available, there is no readily applicable set of indicators. Hence, this article proposes a holistic sustainability impact assessment method tailored to the management of urban surfaces and their innovations. For the development of the method, a Sustainable Development Goal (SDG)-based, top-down approach is adopted. The proposed assessment method makes it possible to identify an innovation’s potential contribution to the achievement of the SDGs before its introduction. In this article, the assessment method is tested by evaluating the sustainability impacts of weed-suppressing joint filling sand on a walkway in a municipal cemetery in Southern Germany. The case study shows that a mixed impact of the innovation in the three dimensions of sustainability could be expected within the system boundary. It highlights the need for innovation optimization, mainly in the economic dimension. As a result, the introduced method can support the innovation process of urban surfaces for sustainable municipal development.

scholarly journals 3D Building Reconstruction Using Dense Photogrammetric Point Cloud

2016 ◽  
Vol XLI-B3 ◽  
pp. 71-74 ◽  
Author(s):  
S. Malihi ◽  
M. J. Valadan Zoej ◽  
M. Hahn ◽  
M. Mokhtarzade ◽  
H. Arefi
Keyword(s):  
Spatial Data ◽  
Urban Areas ◽  
City Planning ◽  
Three Dimensional ◽  
Point Clouds ◽  
Building Models ◽  
Geometrical Constraints ◽  
Three Dimensional Models ◽  
3D City Modelling ◽  
Building Reconstruction

Three dimensional models of urban areas play an important role in city planning, disaster management, city navigation and other applications. Reconstruction of 3D building models is still a challenging issue in 3D city modelling. Point clouds generated from multi view images of UAV is a novel source of spatial data, which is used in this research for building reconstruction. The process starts with the segmentation of point clouds of roofs and walls into planar groups. By generating related surfaces and using geometrical constraints plus considering symmetry, a 3d model of building is reconstructed. In a refinement step, dormers are extracted, and their models are reconstructed. The details of the 3d reconstructed model are in LoD3 level, with respect to modelling eaves, fractions of roof and dormers.

scholarly journals 3D Building Reconstruction Using Dense Photogrammetric Point Cloud

2016 ◽  
Vol XLI-B3 ◽  
pp. 71-74 ◽  
Author(s):  
S. Malihi ◽  
M. J. Valadan Zoej ◽  
M. Hahn ◽  
M. Mokhtarzade ◽  
H. Arefi
Keyword(s):  
Spatial Data ◽  
Urban Areas ◽  
City Planning ◽  
Three Dimensional ◽  
Point Clouds ◽  
Building Models ◽  
Geometrical Constraints ◽  
Three Dimensional Models ◽  
3D City Modelling ◽  
Building Reconstruction

Three dimensional models of urban areas play an important role in city planning, disaster management, city navigation and other applications. Reconstruction of 3D building models is still a challenging issue in 3D city modelling. Point clouds generated from multi view images of UAV is a novel source of spatial data, which is used in this research for building reconstruction. The process starts with the segmentation of point clouds of roofs and walls into planar groups. By generating related surfaces and using geometrical constraints plus considering symmetry, a 3d model of building is reconstructed. In a refinement step, dormers are extracted, and their models are reconstructed. The details of the 3d reconstructed model are in LoD3 level, with respect to modelling eaves, fractions of roof and dormers.

convergent-beam diffraction from surfaces

1987 ◽  
Vol 45 ◽  
pp. 30-33
Author(s):  
J. A. Eades ◽  
A. E. Smith ◽  
D. F. Lynch
Keyword(s):  
Reciprocal Lattice ◽  
Three Dimensional ◽  
Grazing Incidence ◽  
Three Dimensions ◽  
Plane Figure ◽  
Transmission Electron ◽  
Convergent Beam ◽  
Beam Patterns ◽  
Beam Diffraction

It is quite simple (in the transmission electron microscope) to obtain convergent-beam patterns from the surface of a bulk crystal. The beam is focussed onto the surface at near grazing incidence (figure 1) and if the surface is flat the appropriate pattern is obtained in the diffraction plane (figure 2). Such patterns are potentially valuable for the characterization of surfaces just as normal convergent-beam patterns are valuable for the characterization of crystals.There are, however, several important ways in which reflection diffraction from surfaces differs from the more familiar electron diffraction in transmission.GeometryIn reflection diffraction, because of the surface, it is not possible to describe the specimen as periodic in three dimensions, nor is it possible to associate diffraction with a conventional three-dimensional reciprocal lattice.

Extension of the Spatial PDI Model to Three Dimensions

1997 ◽  
Vol 84 (1) ◽  
pp. 176-178
Author(s):  
Frank O'Brien
Keyword(s):  
Population Density ◽  
Dimensional Space ◽  
Finite Lattice ◽  
Three Dimensional ◽  
Upper Bounds ◽  
Three Dimensions ◽  
Lower And Upper Bounds ◽  
Density Index ◽  
Three Dimensional Space

The author's population density index ( PDI) model is extended to three-dimensional distributions. A derived formula is presented that allows for the calculation of the lower and upper bounds of density in three-dimensional space for any finite lattice.

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.

scholarly journals Free partition functions and an averaged holographic duality

2021 ◽  
Vol 2021 (1) ◽  
Author(s):  
Nima Afkhami-Jeddi ◽  
Henry Cohn ◽  
Thomas Hartman ◽  
Amirhossein Tajdini
Keyword(s):  
Partition Function ◽  
Spectral Gap ◽  
Central Charge ◽  
Three Dimensional ◽  
Two Dimensions ◽  
Three Dimensions ◽  
Partition Functions ◽  
General Constraints ◽  
Dimensional Gravity ◽  
Holographic Duality

Abstract We study the torus partition functions of free bosonic CFTs in two dimensions. Integrating over Narain moduli defines an ensemble-averaged free CFT. We calculate the averaged partition function and show that it can be reinterpreted as a sum over topologies in three dimensions. This result leads us to conjecture that an averaged free CFT in two dimensions is holographically dual to an exotic theory of three-dimensional gravity with U(1)c×U(1)c symmetry and a composite boundary graviton. Additionally, for small central charge c, we obtain general constraints on the spectral gap of free CFTs using the spinning modular bootstrap, construct examples of Narain compactifications with a large gap, and find an analytic bootstrap functional corresponding to a single self-dual boson.

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