Jiyeong Lee

Emergency response after 9/11: the potential of real-time 3D GIS for quick emergency response in micro-spatial environments

Terrorist attacks at the World Trade Center (WTC) in New York City and the Pentagon on September 11, 2001, not only affected multi-level structures in urban areas but also impacted upon their immediate environment at the street level in ways that considerably reduced the speed of emergency response. In this paper, we examine the potential of using real-time 3D GIS for the development and implementation of GIS-based intelligent emergency response systems (GIERS) that aim at facilitating quick emergency response to terrorist attacks on multi-level structures (e.g. multi-story office buildings). We outline a system architecture and a network data model that integrates the ground transportation system with the internal conduits within multi-level structures into a navigable 3D GIS. We examine important implementation issues of GIERS, especially the need for wireless and mobile deployment. Important decision support functionalities of GIERS are also explored with particular reference to the application of network-based shortest path algorithms. Finally, we present the results of an experimental implementation of an integrated 3D network data model using a GIS database of Franklin County, Ohio (USA). Our study shows that response delay within multi-level structures can be much longer than delays incurred on the ground transportation system, and GIERS have the potential for considerably reducing these delays.

A combinatorial data model for representing topological relations among 3D geographical features in micro‐spatial environments

This research is motivated by the need for 3D GIS data models that allow for 3D spatial query, analysis and visualization of the subunits and internal network structure of ‘micro‐spatial environments’ (the 3D spatial structure within buildings). It explores a new way of representing the topological relationships among 3D geographical features such as buildings and their internal partitions or subunits. The 3D topological data model is called the combinatorial data model (CDM). It is a logical data model that simplifies and abstracts the complex topological relationships among 3D features through a hierarchical network structure called the node‐relation structure (NRS). This logical network structure is abstracted by using the property of Poincaré duality. It is modelled and presented in the paper using graph‐theoretic formalisms. The model was implemented with real data for evaluating its effectiveness for performing 3D spatial queries and visualization.

3D geo-information sciences

Keynotes.- A Virtual Geographic Environment for a Simulation of Air Pollution Dispersion in the Pearl River Delta (PRD) Region.- Representing and Exchanging 3D City Models with CityGML.- Research and Development Program for the Third National Geographic Information System Project in Korea: Korean Land Spatialization Program.- Papers.- Construction Operators for Modelling 3D Objects and Dual Navigation Structures.- A Multilayered Space-Event Model for Navigation in Indoor Spaces.- Towards Defining a Framework for Automatic Generation of Buildings in CityGML Using Building Information Models.- Managed Objects for Infrastructure Data.- Integrating Terrain Surface and Street Network for 3D Routing.- Using a B-Rep Structure to Query 9-Intersection Topological Relationships in 3D GIS - Reviewing the Approach and Improving Performance.- Query Processing in 3D Spatial Databases: Experiences with Oracle Spatial 11g.- Making Interoperability Persistent: A 3D Geo Database Based on CityGML.- Use of Finite Arithmetic in 3D Spatial Databases.- Automatic Digital Aerial Image Resection Controlled by LIDAR Data.- Automatic Surface Patch Generation from a Video Image Sequence.- Indoor 3D Modeling and Visualization with a 3D Terrestrial Laser Scanner.- Automatic Image Mosaic-Building Algorithm for Generating Facade Textures.- 3D Continuous K-NN Query for a Landmark-based Wayfinding Location-based Service.- 3D Geo-Network for Agent-based Building Evacuation Simulation.- Hierarchical Modelling of Multi-Geospatial Databases as Basis for Geo-Oriented 3D Analysis Capabilities.- Solar Radiation over the Urban Texture: LIDAR Data and Image Processing Techniques for Environmental Analysis at City Scale.- Creation and Error Analysis of High Resolution DEM Based on Source Data Sets of Various Accuracy.- A Topological Analysis Method for 3D Geo-Entities Structured as Hexahedron Tessellations.- Constraint-based Generation and Visualization of 3D City Models.- GeoVEs as Tools to Communicate in Urban Projects: Requirements for Functionality and Visualization.- Producing 3D Applications for Urban Planning by Integrating 3D Scanned Building Data with Geo-spatial Data.- 3D Dynamic Simulation and Visualization for GIS-based Infiltration Excess Overland Flow Modelling.A complete methodology from the extraction of Light Detection and Ranging (LIDAR) data to the environmental analysis of urban models and the visualization of results is presented. Aim of t he work is to establish a process to investigate digital urban models integra ting cross-disciplinary competences, like remote sensing, GIS, image proces sing and urban and environmental studies. Toward this goal, working on several interfaces, tools and datasets was necessary to provide a conse quent structure to the introduced methodology. Case study for application was a squared area 300 m etres wide in central Geneva where LIDAR data are available. The us of a hybrid approach from raw LIDAR data and vectorial digital maps (GIS data) of buildings footprints for the interpolation of a 2.5 -D urban surface model, with a resolution grid of 0.50 by 0.50 metres, allo wed to refine vertical

Time-Dependent Optimal Routing in Micro-scale Emergency Situation

Geospatial research interests in emergency responses in micro-scale environments have been increased after 9/11. The application requires to define optimal paths in emergency situation, to support evacuees and rescuers. The optimal path defined in this study is used to guide rescuers. So, the path is from entrances to the disaster site (room), not from rooms to entrances in the building. In this study, we propose a time-dependent optimal routing algorithm to develop real-time evacuation systems. The network data that represents navigable spaces in building is used for routing the optimal path. Associated information about environments (for example, number of evacuees or rescuers, capacity of hallways and rooms, type of rooms and so on) is assigned to nodes and edges in the network. The time-dependent optimal path is defined after concerning temporally changed environmental information and the positions of evacuees and rescuer at each time slot for avoiding places jammed with evacuees. To detect the positions of human beings in a building per time period, we use the results of evacuation simulation system to identify the movement patterns of human beings in the emergency situation. We use the simulation data of five or ten seconds time interval, to determine the optimal route for rescuers.

Location-based service using ontology-based semantic queries: A study with a focus on indoor activities in a university context

Abstract Much research on three-dimensional (3D) indoor geographic information systems (GIS) to date has been focused on 3D topological modeling in the context of emergency management and response. Besides emergency situations, however, little is known about other human activities and the effective use and retrieval of semantically relevant information about such activities based on route analysis in complex buildings regarding 3D indoor GIS. This study proposes a location-based service (LBS) using ontology-based semantic queries with a focus on the indoor activities in a university context. An ontology model called ‘University activity ontology’ is designed with regard to the indoor activities at a university for sharing, managing and querying data semantically. In particular, reasoning rules are created for semantic queries to retrieve and provide information about places relevant to a destination with keywords given by users. A 3D network-based topological data model is generated by connecting a road network model and indoor topological network model to calculate the shortest path from an outdoor/indoor location to an indoor destination of interest selected by users among suggested choices. For the implementation, a location-based GIS application is developed based on the Android operating system (OS) with interactive two-dimensional (2D) and 3D visualization.

3D Geo-Network for Agent-based Building Evacuation Simulation

This paper discusses 3D geometric network extraction for building evacuation simulation with an agent-based model. 3D geometric network represents the internal structure of a building, which provides agent-based models with the shortest path for evacuation. 3D geometric network of a building can be built from computer-aided design (CAD) file (vector) and scanned blueprint (raster) through wall extraction and 3D topology construction. We test two wall extraction methods: vector-based medial-axis transformation (MAT) and raster-based thinning. For vector-based MAT, straight MAT is used to extract wall structure from wall polygon generated from CAD data. For raster-based thinning, boundary peeling thinning is used to extract wall structure from scanned blueprint. The extracted 3D geometric network is then used in an agent-based model for building evacuation simulation. In the evacuation simulation, human beings are considered to be the only moving agents. To model human behavior, we adopt a social force model to consider human-to-human and human-to-wall interactions during evacuation. We test simple evacuation scenario in a situation of jam by enforcing different numbers of people in three rooms. The results show that the average velocity increases continuously before jams, decreases during jams at doorways and outer exits, and eventually increases again as individuals escape the jams.

Developing CityGML Indoor ADE to Manage Indoor Facilities

In recent years research interests in 3D geospatial information have been increased to provide location based services and to develop various 3D urban models used in many fields such as urban planning, and disaster management. Especially, due to increasing the scale and complexity of buildings, many researchers have studied to provide the services such as indoor navigation for disaster. In order to manage complicated indoor spatial information efficiently, it is necessary to develop the indoor spatial data model by extending the developed 3D spatial models which have been developed for outdoor space. Although CityGML (City Geography Markup Language) is an international standard model and it supports five Level of Detail for spatial data of urban areas, it is limited to represent and manage indoor facilties in indoor space. In this chapter, we have proposed CityGML Indoor ADE (Application Domain Extensions) applied to implement indoor space and indoor facility management applications. CityGML Indoor ADE is composed of two feature models including indoor space feature model representing space features and indoor facility feature model representing indoor facilities in indoor space. We generate the XML schema of the CityGML Indoor ADE presented by UML diagrams and develop a viewer to visualize the XML documents in order to validate the indoor space feature model. As well, we construct the sample data based on indoor facility feature model to demonstrate the usefulness of the model for indoor facility management applications.

Ensemble of ground subsidence hazard maps using fuzzy logic

Hazard maps of ground subsidence around abandoned underground coal mines (AUCMs) in Samcheok, Korea, were constructed using fuzzy ensemble techniques and a geographical information system (GIS). To evaluate the factors related to ground subsidence, a spatial database was constructed from topographic, geologic, mine tunnel, land use, groundwater, and ground subsidence maps. Spatial data, topography, geology, and various ground-engineering data for the subsidence area were collected and compiled in a database for mapping ground-subsidence hazard (GSH). The subsidence area was randomly split 70/30 for training and validation of the models. The relationships between the detected ground-subsidence area and the factors were identified and quantified by frequency ratio (FR), logistic regression (LR) and artificial neural network (ANN) models. The relationships were used as factor ratings in the overlay analysis to create ground-subsidence hazard indexes and maps. The three GSH maps were then used as new input factors and integrated using fuzzy-ensemble methods to make better hazard maps. All of the hazard maps were validated by comparison with known subsidence areas that were not used directly in the analysis. As the result, the ensemble model was found to be more effective in terms of prediction accuracy than the individual model.

Global Positioning/GPS

Global positioning systems (GPSs) are satellite-based radio positioning systems that provide 24-hour three-dimensional position, velocity, and time information to military and civilian users anywhere on the Earth under any weather condition. The GPS has three major segments: space segment, control segment, and user segment. GPS satellites orbiting the Earth every 12 hours transmit continuous navigation signals. With the proper equipment, users can receive these signals to calculate time, location, and velocity. The GPS is rapidly becoming an integral component of the emerging global information infrastructure, with applications ranging from mapping and surveying to international air traffic management, location-based services (LBS), and global change research. Also, the GPS is increasingly used in the social sciences to support researches for which real-time geographic location and time on human spatial activities are required.

Improving rendering speed of 3D geospatial data based on HTML5/WebGL using improved arithmetic operation speed

ABSTRACT The plug-in must be installed in the web environment to enable 3D spatial data service. Increasingly, these plug-ins are unused owing to installation errors, unsupported cross-browser compatibility, and security vulnerabilities. Specifically, in 2015, the NPAPI service was terminated and is now running only on applications based on Internet Explorer. In response, HTML5/WebGL (next-generation Web standard, confirmed in October 2014) technology has emerged. WebGL has been able to display 3D spatial data without any plug-in in any browser. In this study, we attempted to identify the necessary technologies and limitations for 3D spatial data display using HTML5/WebGL and suggested ways to improve the display speed. We used Emscripten technology to improve the speed of arithmetic operations. To conduct an experimental implementation on the proposed method, we used the 3D data provided by ‘Spatial Information Open Platform (VWorld)’ in Korea and analyzed the display speed of 3D spatial data in terms of frames per second and rendering time.