The development of the next major version 3.0 of the international OGC standard CityGML is nearing its end. CityGML 3.0 will come up with a variety of new features and revisions of existing modules that will increase the usability of CityGML for more user groups and areas of application. This includes a new space concept, a revised level-of-detail (LOD) concept, the representation of time-dependent properties, the possibility to manage multiple versions of cities, the representation of city objects by point clouds, an improved modelling of constructions, the representation of building units and storeys, an improved representation of traffic infrastructure as well as a clear separation of the conceptual model and the data encodings that allow for providing further encoding specifications besides GML. This paper gives an overview of these new and revised concepts, and illustrates their application through selected use cases. KeywordsCityGML 3.0 · 3D city models · Space concept Zusammenfassung CityGML 3.0: Neue Funktionen eröffnen neue Anwendungen. Die Entwicklung der nächsten Hauptversion 3.0 des internationalen OGC-Standards CityGML nähert sich dem Ende. CityGML 3.0 wird mit einer Vielzahl an neuen Funktionen und der Überarbeitung bestehender Module aufwarten, die die Benutzerfreundlichkeit von CityGML für weitere Benutzergruppen und Anwendungsbereiche verbessern. Dazu gehören ein neues Space-Konzept, ein überarbeitetes Level-of-Detail (LOD)-Konzept, die Darstellung von zeitabhängigen Eigenschaften, die Möglichkeit, mehrere Versionen von Stadtmodellen gleichzeitig zu verwalten, die Darstellung von Stadtobjekten durch Punktwolken, eine verbesserte Modellierung von sonstigen Bauwerken, die Darstellung von Gebäudeeinheiten und Etagen, eine verbesserte Darstellung der Verkehrsinfrastruktur sowie eine klare Trennung des konzeptuellen Modells von der Datenhaltung, die es erlaubt, neben GML weitere Datenformate bereitzustellen. Dieser Artikel gibt einen Überblick über die neuen und überarbeiteten Konzepte und veranschaulicht ihre Anwendung anhand ausgewählter Beispiele.

Semantic 3D city models describe city entities by objects with thematic and spatial attributes and their interrelationships. Today, more and more cities worldwide are representing their 3D city models according to the CityGML standard issued by the Open Geospatial Consortium (OGC). Various application areas of 3D city models such as urban planning or architecture require that authorities or stakeholders manage parallel alternative versions of city models and their evolution over time, which is currently not supported by the CityGML standard 2.0. In this paper, we propose a concept and a data model extending CityGML by denoting versions of models or model elements as planning alternatives. We support transitions between these versions to manage history or evolution of the city models over time. This approach facilitates the interoperable integration and exchange of different versions of a 3D city model within one dataset, including a possibly complex history of a repository. Such an integrated dataset can be used by different software systems to visualize and work with all the versions. The versions and version transitions in our proposed data model are bi-temporal in nature. They are defined as separate feature types, which allow the users to manage versioning and to perform queries about versions using an OGC Web Feature Service. We apply this data model to a use case of planning concurrent versions and demonstrate it with example instance data. The concept is general in the sense that it can be directly applied to other GML-based application schemas including the European INSPIRE data themes and national standards for topography and cadasters like the British Ordnance Survey Mastermap or the German cadaster standard ALKIS.

Abstract. A range of different and increasingly accessible acquisition methods, the possibility for frequent data updates of large areas, and a simple data structure are some of the reasons for the popularity of three-dimensional (3D) point cloud data. While there are multiple techniques for segmenting and classifying point clouds, capabilities of common data formats such as LAS for providing semantic information are mostly limited to assigning points to a certain category (classification). However, several fields of application, such as digital urban twins used for simulations and analyses, require more detailed semantic knowledge. This can be provided by semantic 3D city models containing hierarchically structured semantic and spatial information. Although semantic models are often reconstructed from point clouds, they are usually geometrically less accurate due to generalization processes. First, point cloud data structures / formats are discussed with respect to their semantic capabilities. Then, a new approach for integrating point clouds with semantic 3D city models is presented, consequently combining respective advantages of both data types. In addition to elaborate (and established) semantic concepts for several thematic areas, the new version 3.0 of the international Open Geospatial Consortium (OGC) standard CityGML also provides a PointCloud module. In this paper a scheme is shown, how CityGML 3.0 can be used to provide semantic structures for point clouds (directly or stored in a separate LAS file). Methods and metrics to automatically assign points to corresponding Level of Detail (LoD)2 or LoD3 models are presented. Subsequently, dataset examples implementing these concepts are provided for download.

Current data models for representing, exchanging, and storing utility networks often meet the needs of specific domains only, i.e. they do not consider the integration of different network systems, mutual relations between networks and the embedding into 3D urban space. These important prerequisites for urban analyses and simulations are met by the CityGML extension Utility Network ADE. Originally developed for disaster management, this article presents the further development of the ADE by new and revised concepts that result from an extensive analysis of relevant use cases. A catalogue of requirements is presented, current data models are evaluated against these requirements, and the recent developments and refinements of the ADE are explained in detail. This includes the concepts of inter-feature links and network links, the linking of network components with city objects, the modelling of functional characteristics, a refined network components module, and a new electricity network package. In addition, an overview of projects that successfully have applied the ADE is provided.

Abstract. Japan is currently facing serious issues associated with an aging society and negative population growth. Urban structures, remnants of economic prosperity, are now hindrances to sustainable urban development, driving municipalities to seek efficient methods to manage this growth. Japanese municipalities continuously conduct surveys to collect data for urban planning purposes. However, lack of standardization and poor visualization tools prevent coordination and consensus-building among stakeholders during the planning process. The "i-Urban Revitalization" (i-UR) is an information infrastructure promoted by the Japanese government expected to enable municipalities to analyze and visualize their goals related to that process.This paper presents the implementation of i-UR. One approach employed for data standardization is to develop a CityGML Application Domain Extension (ADE) for urban planning that covers detailed attributes of city objects and mechanisms for global representation and analysis necessary for urban planning. The effectiveness of this ADE is being evaluated through data implementation and visualization experiments conducted in three municipalities in Japan. A prototype for the proposed "AR Consensus-formation system" is being developed for further utilization of the ADE. In addition, Ideathon events are being held to develop human resources in municipalities to promote urban revitalization and facilitate i-UR use. The ADE and i-UR tools described in this paper are expected to evolve based on feedback from users and experimental results.