Over the last decade, more and more cities and even countries worldwide are creating semantic 3D city models of their physical environment based on the international CityGML standard issued by the Open Geospatial Consortium (OGC). CityGML is an open data model and XML-based data exchange format describing the most relevant urban and landscape objects along with their spatial and non-spatial attributes, relations, and their complex hierarchical structures in five levels of detail. 3D city models, which are structured according to CityGML, are often used for various complex GIS simulation and analysis tasks, which go far beyond pure 3D visualization. Due to the large size and complexity of the sometimes country-wide 3D geospatial data, the GIS software vendors and service providers face many challenges when building 3D spatial data infrastructures for realizing the efficient storage, analysis, management, interaction, and visualization of the 3D city models based on the CityGML standard. Hence, there has been strong demand for an open and comprehensive software solution that can provide full support of the aforementioned functionalities. The '3D City Database' (3DCityDB) is a free 3D geo-database solution for CityGMLbased 3D city models. 3DCityDB has been developed as an Open Source and platform-independent software suite to facilitate the development and deployment of 3D city model applications. The 3DCityDB software package consists of a database schema for spatially enhanced relational database management systems (ORACLE Spatial or PostgreSQL/PostGIS) with a set of database procedures and software tools allowing to import, manage, analyze, visualize, and export virtual 3D city models according to the CityGML standard. Within this paper, the software suite is illustrated and explained in detail with respect to the related technical implementations and the underlying conceptual software design. Moreover, the utilization of 3DCityDB in different projects and practical application fields are also presented in this paper.

The planning of large infrastructure facilities such as inner‐city subway tracks requires the consideration of widely differing scales, ranging from the kilometer scale for the general routing of the track down to the centimeter scale for detailed design of connection points. On the one hand this implies the utilization of both, Geographic Information Systems (GIS) as well as Building Information Modeling (BIM) tools, for performing the required analysis, modeling, and visualization tasks. On the other hand, a sound foundation of handling multi‐scale representations is required. Although multi‐scale modeling is already well established in the GIS field, there are no corresponding approaches in Infrastructure BIM so far. However, multi‐scale concepts are also much needed in the BIM context, as the planning process typically provides only rough information in the early stages and increasingly detailed and fine‐grained information in later stages. To meet this demand, this article presents a comprehensive concept for incorporating multi‐scale representations with building information models, with a particular focus on the geometric‐semantic modeling of shield tunnels. Based on a detailed analysis of the data modeling methods used in CityGML and the requirements present in the context of infrastructure planning projects, we discuss potential extensions to the BIM data model Industry Foundation Classes (IFC) for incorporating multi‐scale representations of shield tunnels. Particular emphasis is put on providing means for preserving the consistency of the representation across the different Levels‐of‐Detail (LoDs), while taking into account both semantics and geometry. For realizing consistency preservation mechanisms, we propose to apply a procedural geometry description which makes it possible to define explicit dependencies between geometric entities on different LoDs. The modification of an object on a coarse level consequently results in an automated update of all dependent objects on the finer levels. Finally, we discuss the transformation of the IFC‐based multi‐scale tunnel model into a CityGML compliant tunnel representation.

This paper considers a novel indoor positioning method that is currently under development at the ETH Zurich. The method relies on a digital spatio-semantic interior building model CityGML and a Range Imaging sensor. In contrast to common indoor positioning approaches, the procedure presented here does not require local physical reference infrastructure, such as WLAN hot spots or reference markers.

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Commission IV, WG IV/7KEY WORDS: Collaborative planning, integration of 3D modeling and simulation, multi-scale modelling, mobile computer vision. ABSTRACT:Computer-aided collaborative and multi-scale 3D planning are challenges for complex railway and subway track infrastructure projects in the built environment. Many legal, economic, environmental, and structural requirements have to be taken into account. The stringent use of 3D models in the different phases of the planning process facilitates communication and collaboration between the stake holders such as civil engineers, geological engineers, and decision makers. This paper presents concepts, developments, and experiences gained by an interdisciplinary research group coming from civil engineering informatics and geo-informatics banding together skills of both, the Building Information Modeling and the 3D GIS world. New approaches including the development of a collaborative platform and 3D multi-scale modelling are proposed for collaborative planning and simulation to improve the digital 3D planning of subway tracks and other infrastructures. Experiences during this research and lessons learned are presented as well as an outlook on future research focusing on Building Information Modeling and 3D GIS applications for cities of the future.

Semantic 3D city modeling and building information modeling (BIM) are methods for modeling, creating, and analyzing three-dimensional representations of physical objects of the environment. Digital modeling of the built environment has been approached from at least four different domains: computer graphics and gaming, planning and construction, urban simulation, and geomatics. This chapter introduces the similarities and differences of 3D models from these disciplines with regard to aspects like scale, level of detail, representation of spatial and semantic characteristics, and appearance. Exemplified by the international standards CityGML and Industry Foundation Classes (IFC), information models from semantic 3D city modeling and BIM and their corresponding modeling approaches are explored, and the relationships between them are discussed. Based on use cases from infrastructure planning, approaches for integrating information from semantic 3D city modeling and BIM, such as semantic transformation between CityGML and IFC, are described. Furthermore, the role of semantic 3D city modeling and BIM for recent developments in urban informatics, such as smart cities and digital twins, is investigated and illustrated by real-world examples.

Abstract. Nowadays, the three-dimensional visualization of cities is becoming feasible and popular. The applications serve key sectors of urban development including architecture and urban planning. The implementation of BIM in the geospatial environment will help in evaluation of the design proposals by answering questions such as “What windows have views of a particular spot?”, “How will a design proposal affect views and shadows in an urban scene?” from multiple stakeholder perspectives.This paper presents an approach that facilitates the integration of BIM and geo visualization. 3DCityDB4BIM is a concept for combining existing open source software and open specifications for efficient data management and visualization of Building Information within its broader context. 3DCityDB4BIM core components are the 3DCityDB, the BIMServer, CesiumJS viewer, and the existing standards (glTF, CityGML and IFC). The paper presents the procedure used to enable the development of this new expert system as applied to the context of 3D Web GIS. A thorough analysis of the strengths and weaknesses of these different components has been undertaken to employ their strengths and overcome their weaknesses. The system architecture is providing an extension to the 3DCityDB linking to BIMServer without violating indoor information privacy issues. The 3D visualization format glTF works as the integration medium to visualize BIM and CityGML data in web browsers without plugins or other additional software on the client side. The developed software is open source.

Information mined from building information models as well as associated geographical data and Geographic Information System (GIS) analyses can increase the success of construction processes and asset management, including buildings, roads, and public facilities. The integration of information from both domains requires high expertise in both spheres. The existing B.Sc and M.Sc. programs linked to the built environment at the Technical University of Munich offer courses for the Building Information Model (BIM) and GIS that are distributed among study programs in Civil Engineering, Architecture, and Geomatics. Students graduating as professionals in one of these domains rarely know how to solve pre-defined technical problems associated with the integration of information from BIM and GIS. Students in such programs seldom practice skills needed for the integration of information from BIM and GIS at a level that is needed in working life. Conversely, the technologies in both domains create artificial boundaries that do not exist in reality—for example, water and electricity would not be of use if the utilities terminated in front of buildings. To bring a change and bridge the gap between BIM and GIS, a change in the teaching methods of BIM/GIS needs to be considered. The Technical University of Munich (TUM) has developed a master’s course (M.Sc. course) for students in Geoinformatics which focuses on competencies required to achieve BIM/GIS integration. This paper describes the course development process and provides a unique perspective on the curriculum and subjects. It also presents the course objective, course development, the selection and development of learning materials, and the assessment of the intended learning outcome of the course. The developed course is validated through a questionnaire, and feedback is provided by participants of the BIM/GIS integration workshop representing a panel of experts in the domain.