Enabling numerical Simulations in semantic 3D City Models using CityGML

Enabling numerical Simulations in
semantic 3D City Models using CityGML
13th South East Asian Survey Congress, Singapore
Arne Schilling Stefan Trometer
virtualcitySYSTEMS GmbH CADFEM GmbH
Berlin, Germany Grafing, Germany

Arne Schilling, virtualcitySYSTEMS , SEASC 20152
 Geoportal Solutions
 What is Urban Simulation?
 Challenge
 Project 1 – Urban Air Flow
 Project 2 – Urban Blast Simulation
 Discussion
Outline

3 Arne Schilling, virtualcitySYSTEMS , SEASC 2015
Geoportal Solutions
Points of
Interest

Geoportal Solutions
Integration of
OGC Services

Geoportal Solutions
Spatial &
Semantic
Queries

What is Urban Simulation?
Simulation of physical phenomena in urban environments using virtual mockups /
3D city models

What is Urban Simulation?
 Mechanical simulations of building structures
 Acoustic studies / blast simulations
 Wind field simulations
 Simulation of flood events
 …

 GIS is not designed for performing complex physical computations
• Strengths of GIS are data management, spatial analysis and visualization
• 3D city models are created using remote sensing and automatic feature
extraction methods, not using CAD software
Challenge

Challenge
 Physical simulations are frequently done in product design
• Using Computer Aided Design (CAD) and Computer Aided Engineering (CAE)
software such as ANSYS
• Based on the Finite Element approach -> Numerical Simulation

Challenge
 Physical simulations are frequently done in product design
• Using Computer Aided Design (CAD) and Computer Aided Engineering (CAE)
software such as ANSYS
• Based on the Finite Element approach -> Numerical Simulation
 Technological gap between GIS and CAE Worlds
• CityGML cannot be loaded by CAE software (e.g. ANSYS). Geometrical
representations are very different -> we need conversion tools
• Requirements on data quality are different
• Simulation results are mostly stored in proprietary formats

Challenge
 Create a workflow from 3D Geographic Information Systems to
Simulation frameworks and back

 Simulating the wind flow in urban environments for calculating pedestrian
comfort levels
 Collaboration with IDAC Ltd.
 Part of Environmental Impact Assessment
Project 1 - Urban Air Flow
Partners
Pedestrian comfort at ground level
(streamlines)
Velocity contours
at a height of 7m and 150m
Novosibirsk State University
of Architecture
and Civil Engineering

 Data set: Frankfurt a.M. Germany: many high rise buildings
 Approach: Computational Fluid Dynamics (CFD) analysis
 Typical wind loads described by velocity profiles were applied
 The Navier-stokes equations were solved along with the 𝑘−𝜀 turbulence model.
 The analysis was performed using ANSYS CFX “high-performance, general
purpose fluid dynamics program”
13
From http://www.ansys.com

Data Link - Geometry Processing
 Format Conversion from CityGML to STEP
 Recreation of geometry and topology
 Error detection and Geometry healing
• no self intersections
• no non-manifold geometries
• no interior surfaces
• no holes (“watertight”)
• no stray elements
 Defeaturing
14
Geometry healing, e.g. removing inner surfaces (top) and
resolving self-intersections (bottom)

Numerical Computations
 Meshing -> ca. 43 Mio. elements
 Setting physical properties (e.g. air density)
 Boundary conditions
 Running CFD solver
15

Presentation
 Cross sections
 Coloring 3D city model
 Charts (velocity contours) for reporting
16

Background
 Unexploded bombs from WW2
 Safety perimeters must be set up quickly
 Critical infrastructure facilities in the area must
be determined
Project 1- Urban Blast Simulation
Safety perimeters (red: evacuation, blue: curfew)
Recovery of defused bomb
Disposal of defused bomb

Approach
 Data exchange using STEP
 Geometry processing (healing)
 Shockwave propagation using AUTODYN and APOLLO solvers
 Reintegration of simulation results in 3D city model
Partners
Funding
Web-Interface for visualization of numerical results

Partners
Funding
Fast solution by the APOLLO
Blastsimulator in cooperation with
the Fraunhofer EMI
Objectives
 Easy accessibility to decision-makers (fire fighers, police, bomb
disposal units etc.)
 Integrated and automatic workflow for scenario definition,
numerical simulation and presentation of results
 Derivation of damage indicators (e.g. broken windows, masonry)

Partners
Funding
Derived detailed
building models from city models
Analysis and optimization of
detailed structural members
H
h
R
x
z
Source: GEORES (www.geores.de)
Further Research
 Investigate vulnerability of buildings to blasts (simulate structural
damages) -> planning purposes
 Increase the resilience of facilities to terroristic threats

Restrictions
• CityGML LOD 2 city models (no windows, balconies etc, roof information), no
information on interior structures
• Simulated area limited to 1x1km (limitation in ANSYS)
• STEP CAD models are not geo-referenced, extension required
Discussion
Steady-state air flow LOD3 model
Super-detailed
structural
simulation

Discussion
Benefits
• Solution can be added to existing Spatial Data Infrastructures
• Solution relies on open standards (CityGML, OGC services) and industry standards
(STEP)
• Data is stored and managed in a central data repository (Oracle, PostgreSQL)
• Will be possible to reintegrate simulation results into 3D city model database
(damage indicators, wind loads)

Current Technology Partners
Urban Simulation Network
Urban Simulation
&
Urban Blast Protection
Flooding & Tsunami
Protection
Urban Air Flow
Smoke & Pollution
Development
Crowd Movement
Novosibirsk State University
of Architecture
and Civil Engineering

Conceptual Approach
ETL processes
Open architecture
• Other applications can be
plugged into / connected to
the 3D SDI
virtualcitySYSTEMS 2015

Thank You
Arne Schilling Stefan Trometer
virtualcitySYSTEMS GmbH CADFEM GmbH
aschilling@virtualcitysystems.de strometer@cadfem.de
http://www.virtualcitysystems.de http://www.cadfem.de

Enabling numerical Simulations in semantic 3D City Models using CityGML

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