Versioning of 3D City Models for Municipality Applications: Needs, Obstacles and Recommendations

Abstract

The use of 3D city models is changing from visualization to complex use cases where they act as 3D base maps. This requires links to registers and continuous updating of the city models. Still, most models never change or are recreated instead of updated. This study identifies obstacles to version management of 3D city models and proposes recommendations to overcome them, with a main focus on the municipality perspective, foremost in the planning and building processes. As part of this study, we investigate whether national building registers can control the version management of 3D city models. A case study based on investigations of standards, interviews and a review of tools is presented. The study uses an architectural model divided into four layers: data collection, building theme, city model and application. All layers require changes when implementing a new versioning method: the data collection layer requires restructuring of technical solutions and work processes, storage of the national building register requires restructuring, versioning capabilities must be propagated to the city model layer, and tools at the application layer must handle temporal information better. Strong incentives for including versioning in 3D city models are essential, as substantial investment is required to implement versioning in all the layers. Only capabilities required by applications should be implemented, as the complexity grows with the number of versioning functionalities. One outcome of the study is a recommendation to link 3D city models more closely to building registers. This enables more complex use in, e.g., building permits and 3D cadastres, and authorities can fetch required (versioning) information directly from the city model layer.

Identification of existing tools and workflows for solar neighborhood planning

“…Some countries have standards for 3D city models with an homogeneous level of detail and interactive options, while others have an heterogeneous level of detail between different neighborhoods and buildings within the same city. The result is that there is a high degree of uncertainty that needs to be addressed (Eriksson & Harrie, 2021;Sun et al, 2019). On the smaller scales -neighborhood and building scale-, the focus has shifted to more detailed analyses, taking into consideration e.g.…”

From consistency to flexibility: Handling spatial information schema thanks to a middleware in a 3D city modeling context

“…Six issues were evaluated and discussed among the data providers' incentives, the database implementation, etc. but more specifically: the need to collect additional lifecycle and versioning information (Eriksson & Harrie, 2021). The problem highlighted on the additional information is that it requires a substantial restructuring of the technical solution and work processes.…”

Hybrid Gis-Bim Approach for the Torino Digital-Twin: The Implementation of a Floor-Level 3d City Geodatabase

“…Considering the idea of 3D metric replicas as proper prerequisites of modelling Digital Twins for our cities, the selection of standard approaches and common languages could represent for the future one of the most important characteristics to improve in undertaking this new era of 3D city models. But at the same times, it is true as well to promote simple and easily procedures, but applicable in generalized approaches for public administration (Eriksson & Harrie, 2021). The possibility to benefit from a 3D enriched representation of human-related areas, especially cities, beyond the traditional 2D/2.5D mapping point of view, is an essential starting point as well.…”

“…This goal is far from being achieved yet and the challenge requires us to test the strategies with real case studies as many cities are undertaking (Lehner & Dorffner, 2020) and implements the research on replicable methodologies, common languages and standards updating. Nevertheless, the purposes of integration for existing data making them efficiently used and different expert-related languages in favour of interoperability in public administration, is among the most pursued objectives, also and above all from a holistic and empirical point of view (Eriksson & Harrie, 2021). Very often, municipalities offices have at their disposal a large amount of information, in terms of many different archives that have been conceived at different times and for different purposes too.…”