Integrating human perception in 3D city models and urban digital twins

Urban digital twins, and 3D city models underpinning them, provide novel solutions to urban management but tend to overlook the human element. The trending research on human perception reveals people’s perspective towards interpreting and experiencing the built environment. Advancing the representation of building physics and descriptive information in 3D city models and urban digital twins, we establish the addition and integration of the notion of how humans perceive buildings. Unlocking a new dimension in our domain, this new concept can facilitate a broader adoption of semantic 3D data in socio-economic fields across various domains, and advance existing use cases in 3D GIS. This work is the first instance of integrating such attributes in 3D city models, which have traditionally been confined to physical and objective measures. The visual perception of each building is evaluated based on building images extracted from street view images. We add such information as new attributes to an existing CityJSON dataset representing thousands of 3D buildings in Amsterdam, the Netherlands. To facilitate a robust and sustainable integration, we develop a CityJSON Extension to accommodate the new data and validate its schema successfully, and we visualise the semantic 3D dataset. Further, we present two use cases to demonstrate the usability of our new data for downstream analysis. One is the concurrent clustering of buildings based on 3D morphology and human perception, while the other is conducting an attribute-based query that enables various stakeholders to identify a particular building of interest combining both traditional and perception attributes

Integration of Movement Data into 3D GIS

With the rise in usage of digital twins in the field of urban planning, the integration of data sources such as sensor data in 3D city models is a challenge that is often brought up. This is even more so with movement data, as they contain a geographical or geometrical aspect that is often overlooked. This paper looks at existing methods to integrate sensor data with 3D city models, and especially at the Dynamizer module in CityGML that supports the integration of dynamic data into the models directly. We look at how the Dynamizer module works with movement data and compare it with another method, SensorThings API. The comprehensive investigation we conduct involved different types of movement data, at different spatial and temporal scales, e.g. origin-destination public transport data in Singapore and London, migration routes in the USA, and highly detailed customer movement in a supermarket in China. While the Dynamizer is more flexible in representing data, it has less support and it is more restrictive when accessing the data. On the other hand, the FROST-Server implementation of the SensorThings API is more restrictive in representing data, however, accessing the data is more flexible

Geobim benchmark 2019: Design and initial results

GeoBIM, the integration of 3D geoinformation (Geo) with building information models (BIM), is a subject of increasing attention in both domains. A well-known practical challenge for this integration is the mixed state of software support for open standards in each domain that would ease the integration. This is often known by practitioners but poorly documented. In order to solve this problem, we devised the GeoBIM benchmark, in which we compile the experiences of volunteering participants, who perform a guided study to test the software they are most familiar with against a few provided datasets structured in open standards. The aim of the tests is to improve the knowledge of the state of the art in the software support for GeoBIM open standards and to identify points for improvement. In this paper, we present the design of the benchmark, especially explaining and discussing the chosen data to be used with their connected issues to be tested, and some initial results

GeoBIM Benchmark 2019: Intermediate results

An investigation into the implementation state of open standards in software is currently ongoing through the ISPRS/EuroSDR 'GeoBIM benchmark 2019' initiative, which kicked off earlier this year. The benchmark activity provides a way of assessing and comparing the functionality of different software packages in GIS and BIM in terms of their ability to handle standardised data (IFC and CityGML) and undertake various tasks using this data. Approximately 65 people have registered to participate so far, with participants from a wide range of backgrounds and proposing to test a variety of software packages. This confirms that the issues under investigation are of interest, and also meets the wider benchmark aim of having a variety of participants, since the project is conceived as using a bottom-up approach with cross-disciplinary and cross-expertise participation. While full benchmark results are not due to be submitted until later this year, interim results have highlighted a number of common issues across multiple software packages, and a web meeting for participants held in July 2019 also led to some improvements in how the benchmark results are being captured

Digital Twin and Wearables Unveiling Pedestrian Comfort Dynamics and Walkability in Cities

This research examines the interplay of outdoor thermal comfort, walkability, and three-dimensional geospatial landscape within cities. Employing advanced data collection methods, including smart wearables and street view imagery (SVI), we conduct a comprehensive exploration of integrating heterogeneous sensor data and computer vision in an urban digital twin (UDT) we develop. We focus on the integrated thermal walk concept, where participants, equipped with wearables, contribute health metrics and real-time thermal sensation feedback while walking along selected routes for which we collect detailed 3D geoinformation, which in turn provides a foundation for understanding and improving comfort and walkability in cities. Our study not only addresses the integration, but also underscores the transformative role of advanced analytics and UDT in deciphering how urban morphology influences thermal experiences. While the growing accessibility of wearable devices facilitates work such as ours, we highlight challenges in collecting diverse participant data and the imperative need for specialized expertise in UDT and computer vision. This research contributes to (1) digital twins, providing a novel combination of data integration and a new use case, and to (2) urban climatology, advancing our understanding of the relationship among microclimate, urban environment, and outdoor thermal comfort. Beyond theoretical contributions, the study’s practical significance is revealed in the development of accurate predictive models for understanding walkability, promising improvements in the quality of urban life, and pronouncing the important role of 3D geoinformation in such a domain

THE ISPRS-EUROSDR GEOBIM BENCHMARK 2019

Standardised data formats and data models are essential for data integration and interoperability, which in turn adds value to data by allowing its reuse in multiple contexts. For this reason, in recent years extensive efforts have been focused on standards development. When representing the built environment, 3D city models and Building Information Models are particularly relevant, and their integration is now required to underpin use cases that cover the full life-cycle of a built asset, including design and planning as well as operations and management, and to support legal applications such as cadastral systems. For those kinds of data, CityGML by the Open Geospatial Consortium and Industry Foundation Classes by buildingSMART are the most popular reference standards. However, many users report, often through informal channels, the difficulties of working with these formats. This paper summarizes the outcomes of the GeoBIM Benchmark 2019, a scientific initiative funded by ISPRS and EuroSDR to collect insights into the most relevant issues encountered in the management of CityGML and IFC within existing software. Alongside data management (import, visualisation, analysis, export) problems, issues of particular consequence in terms of integration relate to georeferencing IFC files and the conversions among the two kinds of formats and models. Thus, the benchmark was designed to explore these tasks in available software. Following analysis of the benchmark results, a key outcome is the impossibility to find clear patterns in the behaviour of tools, which consequently means there is no consistency in the implementation of standards. Although the results could seem disappointing, the criticality in managing these standards as they are was described and this awareness can be the starting point for further research or further standards development. Finally, this project was useful to gather a wide community around this topic, and the discussion about the GeoBIM-related issues was definitely pushed

FLOOR PLANS IN CITYGML

This paper (1) discusses the modelling of floor plans in CityGML; (2) proposes a delineation of multiple variants of indoor LoD0 in line with the current proposal for CityGML 3.0; (3) demonstrates a method to generate CityGML datasets with included floor plans; and (4) explores their usability. The use of an Application Domain Extension (ADE) is being proposed in order to preserve potentially useful information found within detailed building information models (BIM), specifically Industry Foundation Class (IFC), that cannot be stored in CityGML natively. Our work follows the current developments of CityGML 3.0, and based on the discussions in the CityGML Standards Working Group (SWG) it showcases one of the first datasets consistent with the ongoing development of CityGML 3.0 and one that follows the proposals for a new LOD concept and new interior features

REVISITING THE CONCEPT OF LEVEL OF DETAIL IN 3D CITY MODELLING

This review paper discusses the concept of level of detail in 3D city modelling, and is a first step towards a foundation for a standardised definition. As an introduction, a few level of detail specifications, outlooks and approaches are given from the industry. The paper analyses the general uncertainties and shortcomings around the concept of level of detail in 3D city modelling such as ordinality and inconsistencies, and identifies factors that constitute a specific level of detail. The paper proposes a framework for a new consistent LoD definition which would consolidate present and future LoD paradigms, gives an example of an LoD specification, discusses open questions such as the contexts for which 3D city models are used in practice, and gives prospects for a future quantification and sorting of levels of detail

IFC2INDOORGML: an open-source tool for generating indoorgml from ifc

The interest in 3D indoor models has been continuously growing. Most such models are made available as point clouds or BIM (e.g., IFC), the former being generally provided as unstructured information while the latter comes highly structured and rich in semantic information. IFC models are consequently more suitable for direct use, but they can be very complex and contain too many details, which often raises privacy concerns. IndoorGML is one of the standards for describing 3D indoor space with the purpose of supporting Location Based Services (LBS). It relies on solid scientific concepts and offers a high flexibility with extension mechanisms. It provides a geometric, topological, and semantic description of the indoor which facilitates specifically applications like indoor navigation or facility management. Additionally, it can represent complex indoor environments without compromising privacy, thanks to its high level of abstraction. However, despite its solid conceptual basis, IndoorGML is suffering from a lack of practical tools and remains hard to produce, making it largely unavailable. In this project, we developed an open-source tool named ifc2indoorgml allowing to automatically generate IndoorGML models from IFC data. We discuss the workflow and the different development approaches. By making such tool available to the wider public, we expect more 3D IndoorGML models to be created and made freely available for research and development within the spatial community and beyond.Ministerio de Ciencia e Innovación | Ref. RYC2020-029193-

Proposal for a new LoD and multi-representation concept for CityGML

The Open Geospatial Consortium (OGC) CityGML standard offers a Level of Detail (LoD) concept that enables the representation of CityGML features from a very detailed to a less detailed description. Due to a rising application variety, the current LoD concept seems to be too inflexible. Here, we present a multi representation concept (MRC) that enables a user-defined definition of LoDs. Because CityGML is an international standard, official profiles of the MRC are proposed. However, encoding of the defined profiles reveals many problems including mapping the conceptual model to the normative encoding, missing technologies and so on. Therefore, we propose to use the MRC as a meta model for the further definition of an LoD concept for CityGML 3.0