The representation and management of evolving features in geospatial databases

Geographic features change over time, this change being the result of some kind of event or occurrence. It has been a research challenge to represent this data in a manner that reflects human perception. Most database systems used in geographic information systems (GIS) are relational, and change is either captured by exhaustively storing all versions of data, or updates replace previous versions. This stems from the inherent diffculty of modelling geographic objects in relational tables. This diffculty is compounded when the necessary time dimension is introduced to model how those objects evolve. There is little doubt that the object-oriented (OO) paradigm holds signi cant advantages over the relational model when it comes to modelling real-world entities and spatial data, and it is argued that this contention is particularly true when it comes to spatio-temporal data. This thesis describes an object-oriented approach to the design of a conceptual model for representing spatio-temporal geographic data, called the Feature Evolution Model (FEM), based on states and events. The model was used to implement a spatio-temporal database management system in Oracle Spatial, and an interface prototype is described that was used to evaluate the system by enabling querying and visualisation

Interoperability of Traffic Infrastructure Planning and Geospatial Information Systems

Building Information Modelling (BIM) as a Model-based design facilitates to investigate multiple solutions in the infrastructure planning process. The most important reason for implementing model-based design is to help designers and to increase communication between different design parties. It decentralizes and coordinates team collaboration and facilitates faster and lossless project data exchange and management across extended teams and external partners in project lifecycle. Infrastructure are fundamental facilities, services, and installations needed for the functioning of a community or society, such as transportation, roads, communication systems, water and power networks, as well as power plants. Geospatial Information Systems (GIS) as the digital representation of the world are systems for maintaining, managing, modelling, analyzing, and visualizing of the world data including infrastructure. High level infrastructure suits mostly facilitate to analyze the infrastructure design based on the international or user defined standards. Called regulation1-based design, this minimizes errors, reduces costly design conflicts, increases time savings and provides consistent project quality, yet mostly in standalone solutions. Tasks of infrastructure usually require both model based and regulation based design packages. Infrastructure tasks deal with cross-domain information. However, the corresponding data is split in several domain models. Besides infrastructure projects demand a lot of decision makings on governmental as well as on private level considering different data models. Therefore lossless flow of project data as well as documents like regulations across project team, stakeholders, governmental and private level is highly important. Yet infrastructure projects have largely been absent from product modelling discourses for a long time. Thus, as will be explained in chapter 2 interoperability is needed in infrastructure processes. Multimodel (MM) is one of the interoperability methods which enable heterogeneous data models from various domains get bundled together into a container keeping their original format. Existing interoperability methods including existing MM solutions can’t satisfactorily fulfill the typical demands of infrastructure information processes like dynamic data resources and a huge amount of inter model relations. Therefore chapter 3 concept of infrastructure information modelling investigates a method for loose and rule based coupling of exchangeable heterogeneous information spaces. This hypothesis is an extension for the existing MM to a rule-based Multimodel named extended Multimodel (eMM) with semantic rules – instead of static links. The semantic rules will be used to describe relations between data elements of various models dynamically in a link-database. Most of the confusion about geospatial data models arises from their diversity. In some of these data models spatial IDs are the basic identities of entities and in some other data models there are no IDs. That is why in the geospatial data, data structure is more important than data models. There are always spatial indexes that enable accessing to the geodata. The most important unification of data models involved in infrastructure projects is the spatiality. Explained in chapter 4 the method of infrastructure information modelling for interoperation in spatial domains generate interlinks through spatial identity of entities. Match finding through spatial links enables any kind of data models sharing spatial property get interlinked. Through such spatial links each entity receives the spatial information from other data models which is related to the target entity due to sharing equivalent spatial index. This information will be the virtual properties for the object. The thesis uses Nearest Neighborhood algorithm for spatial match finding and performs filtering and refining approaches. For the abstraction of the spatial matching results hierarchical filtering techniques are used for refining the virtual properties. These approaches focus on two main application areas which are product model and Level of Detail (LoD). For the eMM suggested in this thesis a rule based interoperability method between arbitrary data models of spatial domain has been developed. The implementation of this method enables transaction of data in spatial domains run loss less. The system architecture and the implementation which has been applied on the case study of this thesis namely infrastructure and geospatial data models are described in chapter 5. Achieving afore mentioned aims results in reducing the whole project lifecycle costs, increasing reliability of the comprehensive fundamental information, and consequently in independent, cost-effective, aesthetically pleasing, and environmentally sensitive infrastructure design.:ABSTRACT 4 KEYWORDS 7 TABLE OF CONTENT 8 LIST OF FIGURES 9 LIST OF TABLES 11 LIST OF ABBREVIATION 12 INTRODUCTION 13 1.1. A GENERAL VIEW 14 1.2. PROBLEM STATEMENT 15 1.3. OBJECTIVES 17 1.4. APPROACH 18 1.5. STRUCTURE OF THESIS 18 INTEROPERABILITY IN INFRASTRUCTURE ENGINEERING 20 2.1. STATE OF INTEROPERABILITY 21 2.1.1. Interoperability of GIS and BIM 23 2.1.2. Interoperability of GIS and Infrastructure 25 2.2. MAIN CHALLENGES AND RELATED WORK 27 2.3. INFRASTRUCTURE MODELING IN GEOSPATIAL CONTEXT 29 2.3.1. LamdXML: Infrastructure Data Standards 32 2.3.2. CityGML: Geospatial Data Standards 33 2.3.3. LandXML and CityGML 36 2.4. INTEROPERABILITY AND MULTIMODEL TECHNOLOGY 39 2.5. LIMITATIONS OF EXISTING APPROACHES 41 INFRASTRUCTURE INFORMATION MODELLING 44 3.1. MULTI MODEL FOR GEOSPATIAL AND INFRASTRUCTURE DATA MODELS 45 3.2. LINKING APPROACH, QUERYING AND FILTERING 48 3.2.1. Virtual Properties via Link Model 49 3.3. MULTI MODEL AS AN INTERDISCIPLINARY METHOD 52 3.4. USING LEVEL OF DETAIL (LOD) FOR FILTERING 53 SPATIAL MODELLING AND PROCESSING 58 4.1. SPATIAL IDENTIFIERS 59 4.1.1. Spatial Indexes 60 4.1.2. Tree-Based Spatial Indexes 61 4.2. NEAREST NEIGHBORHOOD AS A BASIC LINK METHOD 63 4.3. HIERARCHICAL FILTERING 70 4.4. OTHER FUNCTIONAL LINK METHODS 75 4.5. ADVANCES AND LIMITATIONS OF FUNCTIONAL LINK METHODS 76 IMPLEMENTATION OF THE PROPOSED IIM METHOD 77 5.1. IMPLEMENTATION 78 5.2. CASE STUDY 83 CONCLUSION 89 6.1. SUMMERY 90 6.2. DISCUSSION OF RESULTS 92 6.3. FUTURE WORK 93 BIBLIOGRAPHY 94 7.1. BOOKS AND PAPERS 95 7.2. WEBSITES 10

Mobile 2D and 3D Spatial Query Techniques for the Geospatial Web

The increasing availability of abundant geographically referenced information in the Geospatial Web provides a variety of opportunities for developing value-added LBS applications. However, large data volumes of the Geospatial Web and small mobile device displays impose a data visualization problem, as the amount of searchable information overwhelms the display when too many query results are returned. Excessive returned results clutter the mobile display, making it harder for users to prioritize information and causes confusion and usability problems. Mobile Spatial Interaction (MSI) research into this “information overload” problem is ongoing where map personalization and other semantic based filtering mechanisms are essential to de-clutter and adapt the exploration of the real-world to the processing/display limitations of mobile devices. In this thesis, we propose that another way to filter this information is to intelligently refine the search space. 3DQ (3-Dimensional Query) is our novel MSI prototype for information discovery on today’s location and orientation-aware smartphones within 3D Geospatial Web environments. Our application incorporates human interactions (interpreted from embedded sensors) in the geospatial query process by determining the shape of their actual visibility space as a query “window” in a spatial database, e.g. Isovist in 2D and Threat Dome in 3D. This effectively applies hidden query removal (HQR) functionality in 360º 3D that takes into account both the horizontal and vertical dimensions when calculating the 3D search space, significantly reducing display clutter and information overload on mobile devices. The effect is a more accurate and expected search result for mobile LBS applications by returning information on only those objects visible within a user’s 3D field-of-view. ii

Mobile 2D and 3D Spatial Query Techniques for the Geospatial Web

The increasing availability of abundant geographically referenced information in the Geospatial Web provides a variety of opportunities for developing value-added LBS applications. However, large data volumes of the Geospatial Web and small mobile device displays impose a data visualization problem, as the amount of searchable information overwhelms the display when too many query results are returned. Excessive returned results clutter the mobile display, making it harder for users to prioritize information and causes confusion and usability problems. Mobile Spatial Interaction (MSI) research into this “information overload” problem is ongoing where map personalization and other semantic based filtering mechanisms are essential to de-clutter and adapt the exploration of the real-world to the processing/display limitations of mobile devices. In this thesis, we propose that another way to filter this information is to intelligently refine the search space. 3DQ (3-Dimensional Query) is our novel MSI prototype for information discovery on today’s location and orientation-aware smartphones within 3D Geospatial Web environments. Our application incorporates human interactions (interpreted from embedded sensors) in the geospatial query process by determining the shape of their actual visibility space as a query “window” in a spatial database, e.g. Isovist in 2D and Threat Dome in 3D. This effectively applies hidden query removal (HQR) functionality in 360º 3D that takes into account both the horizontal and vertical dimensions when calculating the 3D search space, significantly reducing display clutter and information overload on mobile devices. The effect is a more accurate and expected search result for mobile LBS applications by returning information on only those objects visible within a user’s 3D field-of-view

Functionality and performance: two important considerations when implementing topology in 3D.

This thesis contributes to the understanding of the use of topology in analysing 3D spatial data, focussing in particular on two aspects of the problem - what binary topological analysis functionality is required in a commercial 3D Geographical Information System (GIS), and how should this functionality be implemented to achieve the most efficient query performance. Topology is defined as the identification of spatial relationships between adjacent or neighbouring objects. The first stage of this research, a review of applications of topology, results in a generic list of requirements for topology in 3D. This was carried out in parallel with a review of topological frameworks and the relationships identified by one of the frameworks, Egenhofer and Herring's 9-Intersection, selected for implementation. Three generic binary relationship queries are identified (Find Objects with a Specific Relationship, Find Intersecting Objects and What Relationship is there Between These Objects) and a mechanism described to allow these to be adapted to specific application terminology. Approaches to the implementation of 3D binary topological queries include the use of data structures and an As-Required calculation, where computational geometry algorithms are run to determine relationships each time the user runs a query. The Three-Dimensional Formal Data Structure (3DFDS) was selected as a representative example of a Boundary-Representation (B- Rep) structure in GIS. Given the number of joins to be traversed when identifying binary relationships from a B-Rep structure, along with the requirement to query additional containment exception tables, an alternate structure, the Simplified Topological Structure (STS), was proposed to improve binary query performance. Binary relationship queries were developed and comparative performance tests carried out against 3DFDS, STS and a Proxy for the As-Required calculation, using a 1.08 million object test dataset. Results show that STS provides a significant performance improvement over 3DFDS. No definitive conclusion could be drawn when comparing STS with the Proxy for the As-Required approach

GeoYCSB: A Benchmark Framework for the Performance and Scalability Evaluation of Geospatial NoSQL Databases

The proliferation of geospatial applications has tremendously increased the variety, velocity, and volume of spatial data that data stores have to manage. Traditional relational databases reveal limitations in handling such big geospatial data, mainly due to their rigid schema requirements and limited scalability. Numerous NoSQL databases have emerged and actively serve as alternative data stores for big spatial data. This study presents a framework, called GeoYCSB, developed for benchmarking NoSQL databases with geospatial workloads. To develop GeoYCSB, we extend YCSB, a de facto benchmark framework for NoSQL systems, by integrating into its design architecture the new components necessary to support geospatial workloads. GeoYCSB supports both microbenchmarks and macrobenchmarks and facilitates the use of real datasets in both. It is extensible to evaluate any NoSQL database, provided they support spatial queries, using geospatial workloads performed on datasets of any geometric complexity. We use GeoYCSB to benchmark two leading document stores, MongoDB and Couchbase, and present the experimental results and analysis. Finally, we demonstrate the extensibility of GeoYCSB by including a new dataset consisting of complex geometries and using it to benchmark a system with a wide variety of geospatial queries: Apache Accumulo, a wide-column store, with the GeoMesa framework applied on top

Fachlich erweiterbare 3D-Stadtmodelle – Management, Visualisierung und Interaktion

Domain-extendable semantic 3D city models are complex mappings and inventories of the urban environment which can be utilized as an integrative information backbone to facilitate a range of application fields like urban planning, environmental simulations, disaster management, and energy assessment. Today, more and more countries and cities worldwide are creating their own 3D city models based on the CityGML specification which is an international standard issued by the Open Geospatial Consortium (OGC) to provide an open data model and XML-based format for describing the relevant urban objects with regards to their 3D geometry, topology, semantics, and appearance. It especially provides a flexible and systematic extension mechanism called “Application Domain Extension (ADE)” which allows third parties to dynamically extend the existing CityGML definitions with additional information models from different application domains for representing the extended or newly introduced geographic object types within a common framework. However, due to the consequent large size and high model complexity, the practical utilization of country-wide CityGML datasets has posed a tremendous challenge regarding the setup of an extensive application system to support the efficient data storage, analysis, management, interaction, and visualization. These requirements have been partly solved by the existing free 3D geo-database solution called ‘3D City Database (3DCityDB)’ which offers a rich set of functionalities for dealing with standard CityGML data models, but lacked the support for CityGML ADEs. The key motivation of this thesis is to develop a reliable approach for extending the existing database solution to support the efficient management, visualization, and interaction of large geospatial data elements of arbitrary CityGML ADEs. Emphasis is first placed on answering the question of how to dynamically extend the relational database schema by parsing and interpreting the XML schema files of the ADE and dynamically create new database tables accordingly. Based on a comprehensive survey of the related work, a new graph-based framework has been proposed which uses typed and attributed graphs for semantically representing the object-oriented data models of CityGML ADEs and utilizes graph transformation systems to automatically generate compact table structures extending the 3DCityDB. The transformation process is performed by applying a series of fine-grained graph transformation rules which allow users to declaratively describe the complex mapping rules including the optimization concepts that are employed in the development of the 3DCityDB database schema. The second major contribution of this thesis is the development of a new multi-level system which can serve as a complete and integrative platform for facilitating the various analysis, simulation, and modification operations on the complex-structured 3D city models based on CityGML and 3DCityDB. It introduces an additional application level based on a so-called ‘app-concept’ that allows for constructing a light-weight web application to reach a good balance between the high data model complexity and the specific application requirements of the end users. Each application can be easily built on top of a developed 3D web client whose functionalities go beyond the efficient 3D geo-visualization and interactive exploration, and also allows for performing collaborative modifications and analysis of 3D city models by taking advantage of the Cloud Computing technology. This multi-level system along with the extended 3DCityDB have been successfully utilized and evaluated by many practical projects.Fachlich erweiterbare semantische 3D-Stadtmodelle sind komplexe Abbildungen und Datenbestände der städtischen Umgebung, die als ein integratives Informationsrückgrat genutzt werden können, um eine Reihe von Anwendungsfeldern wie z. B. Stadtplanung, Umweltsimulationen, Katastrophenmanagement und Energiebewertung zu ermöglichen. Heute schaffen immer mehr Länder und Städte weltweit ihre eigenen 3D-Stadtmodelle auf Basis des internationalen Standards CityGML des Open Geospatial Consortium (OGC), um ein offenes Datenmodell und ein XML-basiertes Format zur Beschreibung der relevanten Stadtobjekte in Bezug auf ihre 3D-Geometrien, Topologien, Semantik und Erscheinungen zur Verfügung zu stellen. Es bietet insbesondere einen flexiblen und systematischen Erweiterungsmechanismus namens „Application Domain Extension“ (ADE), der es Dritten ermöglicht, die bestehenden CityGML-Definitionen mit zusätzlichen Informationsmodellen aus verschiedenen Anwendungsdomänen dynamisch zu erweitern, um die erweiterten oder neu eingeführten Stadtobjekt-Typen innerhalb eines gemeinsamen Framework zu repräsentieren. Aufgrund der konsequent großen Datenmenge und hohen Modellkomplexität bei der praktischen Nutzung der landesweiten CityGML-Datensätze wurden jedoch enorme Anforderungen an den Aufbau eines umfangreichen Anwendungssystems zur Unterstützung der effizienten Speicherung, Analyse, Verwaltung, Interaktion und Visualisierung der Daten gestellt. Die bestehende kostenlose 3D-Geodatenbank-Lösung „3D City Database“ (3DCityDB) entsprach bereits teilweise diesen Anforderungen, indem sie zwar eine umfangreiche Funktionalität für den Umgang mit den Standard-CityGML-Datenmodellen, jedoch keine Unterstützung für CityGML-ADEs bietet. Die Schlüsselmotivation für diese Arbeit ist es, einen zuverlässigen Ansatz zur Erweiterung der bestehenden Datenbanklösung zu entwickeln, um das effiziente Management, die Visualisierung und Interaktion großer Datensätze beliebiger CityGML-ADEs zu unterstützen. Der Schwerpunkt liegt zunächst auf der Beantwortung der Schlüsselfrage, wie man das relationale Datenbankschema dynamisch erweitern kann, indem die XML-Schemadateien der ADE analysiert und interpretiert und anschließend dem entsprechende neue Datenbanktabellen erzeugt werden. Auf Grundlage einer umfassenden Studie verwandter Arbeiten wurde ein neues graphbasiertes Framework entwickelt, das die typisierten und attributierten Graphen zur semantischen Darstellung der objektorientierten Datenmodelle von CityGML-ADEs verwendet und anschließend Graphersetzungssysteme nutzt, um eine kompakte Tabellenstruktur zur Erweiterung der 3DCityDB zu generieren. Der Transformationsprozess wird durch die Anwendung einer Reihe feingranularer Graphersetzungsregeln durchgeführt, die es Benutzern ermöglicht, die komplexen Mapping-Regeln einschließlich der Optimierungskonzepte aus der Entwicklung des 3DCityDB-Datenbankschemas deklarativ zu formalisieren. Der zweite wesentliche Beitrag dieser Arbeit ist die Entwicklung eines neuen mehrstufigen Systemkonzepts, das auf CityGML und 3DCityDB basiert und gleichzeitig als eine komplette und integrative Plattform zur Erleichterung der Analyse, Simulationen und Modifikationen der komplex strukturierten 3D-Stadtmodelle dienen kann. Das Systemkonzept enthält eine zusätzliche Anwendungsebene, die auf einem sogenannten „App-Konzept“ basiert, das es ermöglicht, eine leichtgewichtige Applikation bereitzustellen, die eine gute Balance zwischen der hohen Modellkomplexität und den spezifischen Anwendungsanforderungen der Endbenutzer erreicht. Jede Applikation lässt sich ganz einfach mittels eines bereits entwickelten 3D-Webclients aufbauen, dessen Funktionalitäten über die effiziente 3D-Geo-Visualisierung und interaktive Exploration hinausgehen und auch die Durchführung kollaborativer Modifikationen und Analysen von 3D-Stadtmodellen mit Hilfe von der Cloud-Computing-Technologie ermöglichen. Dieses mehrstufige System zusammen mit dem erweiterten 3DCityDB wurde erfolgreich in vielen praktischen Projekten genutzt und bewertet

Fachlich erweiterbare 3D-Stadtmodelle – Management, Visualisierung und Interaktion

Domain-extendable semantic 3D city models are complex mappings and inventories of the urban environment which can be utilized as an integrative information backbone to facilitate a range of application fields like urban planning, environmental simulations, disaster management, and energy assessment. Today, more and more countries and cities worldwide are creating their own 3D city models based on the CityGML specification which is an international standard issued by the Open Geospatial Consortium (OGC) to provide an open data model and XML-based format for describing the relevant urban objects with regards to their 3D geometry, topology, semantics, and appearance. It especially provides a flexible and systematic extension mechanism called “Application Domain Extension (ADE)” which allows third parties to dynamically extend the existing CityGML definitions with additional information models from different application domains for representing the extended or newly introduced geographic object types within a common framework. However, due to the consequent large size and high model complexity, the practical utilization of country-wide CityGML datasets has posed a tremendous challenge regarding the setup of an extensive application system to support the efficient data storage, analysis, management, interaction, and visualization. These requirements have been partly solved by the existing free 3D geo-database solution called ‘3D City Database (3DCityDB)’ which offers a rich set of functionalities for dealing with standard CityGML data models, but lacked the support for CityGML ADEs. The key motivation of this thesis is to develop a reliable approach for extending the existing database solution to support the efficient management, visualization, and interaction of large geospatial data elements of arbitrary CityGML ADEs. Emphasis is first placed on answering the question of how to dynamically extend the relational database schema by parsing and interpreting the XML schema files of the ADE and dynamically create new database tables accordingly. Based on a comprehensive survey of the related work, a new graph-based framework has been proposed which uses typed and attributed graphs for semantically representing the object-oriented data models of CityGML ADEs and utilizes graph transformation systems to automatically generate compact table structures extending the 3DCityDB. The transformation process is performed by applying a series of fine-grained graph transformation rules which allow users to declaratively describe the complex mapping rules including the optimization concepts that are employed in the development of the 3DCityDB database schema. The second major contribution of this thesis is the development of a new multi-level system which can serve as a complete and integrative platform for facilitating the various analysis, simulation, and modification operations on the complex-structured 3D city models based on CityGML and 3DCityDB. It introduces an additional application level based on a so-called ‘app-concept’ that allows for constructing a light-weight web application to reach a good balance between the high data model complexity and the specific application requirements of the end users. Each application can be easily built on top of a developed 3D web client whose functionalities go beyond the efficient 3D geo-visualization and interactive exploration, and also allows for performing collaborative modifications and analysis of 3D city models by taking advantage of the Cloud Computing technology. This multi-level system along with the extended 3DCityDB have been successfully utilized and evaluated by many practical projects.Fachlich erweiterbare semantische 3D-Stadtmodelle sind komplexe Abbildungen und Datenbestände der städtischen Umgebung, die als ein integratives Informationsrückgrat genutzt werden können, um eine Reihe von Anwendungsfeldern wie z. B. Stadtplanung, Umweltsimulationen, Katastrophenmanagement und Energiebewertung zu ermöglichen. Heute schaffen immer mehr Länder und Städte weltweit ihre eigenen 3D-Stadtmodelle auf Basis des internationalen Standards CityGML des Open Geospatial Consortium (OGC), um ein offenes Datenmodell und ein XML-basiertes Format zur Beschreibung der relevanten Stadtobjekte in Bezug auf ihre 3D-Geometrien, Topologien, Semantik und Erscheinungen zur Verfügung zu stellen. Es bietet insbesondere einen flexiblen und systematischen Erweiterungsmechanismus namens „Application Domain Extension“ (ADE), der es Dritten ermöglicht, die bestehenden CityGML-Definitionen mit zusätzlichen Informationsmodellen aus verschiedenen Anwendungsdomänen dynamisch zu erweitern, um die erweiterten oder neu eingeführten Stadtobjekt-Typen innerhalb eines gemeinsamen Framework zu repräsentieren. Aufgrund der konsequent großen Datenmenge und hohen Modellkomplexität bei der praktischen Nutzung der landesweiten CityGML-Datensätze wurden jedoch enorme Anforderungen an den Aufbau eines umfangreichen Anwendungssystems zur Unterstützung der effizienten Speicherung, Analyse, Verwaltung, Interaktion und Visualisierung der Daten gestellt. Die bestehende kostenlose 3D-Geodatenbank-Lösung „3D City Database“ (3DCityDB) entsprach bereits teilweise diesen Anforderungen, indem sie zwar eine umfangreiche Funktionalität für den Umgang mit den Standard-CityGML-Datenmodellen, jedoch keine Unterstützung für CityGML-ADEs bietet. Die Schlüsselmotivation für diese Arbeit ist es, einen zuverlässigen Ansatz zur Erweiterung der bestehenden Datenbanklösung zu entwickeln, um das effiziente Management, die Visualisierung und Interaktion großer Datensätze beliebiger CityGML-ADEs zu unterstützen. Der Schwerpunkt liegt zunächst auf der Beantwortung der Schlüsselfrage, wie man das relationale Datenbankschema dynamisch erweitern kann, indem die XML-Schemadateien der ADE analysiert und interpretiert und anschließend dem entsprechende neue Datenbanktabellen erzeugt werden. Auf Grundlage einer umfassenden Studie verwandter Arbeiten wurde ein neues graphbasiertes Framework entwickelt, das die typisierten und attributierten Graphen zur semantischen Darstellung der objektorientierten Datenmodelle von CityGML-ADEs verwendet und anschließend Graphersetzungssysteme nutzt, um eine kompakte Tabellenstruktur zur Erweiterung der 3DCityDB zu generieren. Der Transformationsprozess wird durch die Anwendung einer Reihe feingranularer Graphersetzungsregeln durchgeführt, die es Benutzern ermöglicht, die komplexen Mapping-Regeln einschließlich der Optimierungskonzepte aus der Entwicklung des 3DCityDB-Datenbankschemas deklarativ zu formalisieren. Der zweite wesentliche Beitrag dieser Arbeit ist die Entwicklung eines neuen mehrstufigen Systemkonzepts, das auf CityGML und 3DCityDB basiert und gleichzeitig als eine komplette und integrative Plattform zur Erleichterung der Analyse, Simulationen und Modifikationen der komplex strukturierten 3D-Stadtmodelle dienen kann. Das Systemkonzept enthält eine zusätzliche Anwendungsebene, die auf einem sogenannten „App-Konzept“ basiert, das es ermöglicht, eine leichtgewichtige Applikation bereitzustellen, die eine gute Balance zwischen der hohen Modellkomplexität und den spezifischen Anwendungsanforderungen der Endbenutzer erreicht. Jede Applikation lässt sich ganz einfach mittels eines bereits entwickelten 3D-Webclients aufbauen, dessen Funktionalitäten über die effiziente 3D-Geo-Visualisierung und interaktive Exploration hinausgehen und auch die Durchführung kollaborativer Modifikationen und Analysen von 3D-Stadtmodellen mit Hilfe von der Cloud-Computing-Technologie ermöglichen. Dieses mehrstufige System zusammen mit dem erweiterten 3DCityDB wurde erfolgreich in vielen praktischen Projekten genutzt und bewertet