digital model containing qualitative and quantitative information on a building, and allowing all stakeholders (project owners, architects, engineers, operators, owners, etc.) to coordinate their contributions throughout the lifecycle of the project. This process allows us to optimize the methods of the construction, management and operation of buildings and to become more efficient in terms of cost and time required for the development of a project.
BIM has its origins in 1962, where the basic premises were first established by Douglas C. Engelbart, who in his article “Augmenting Human Intellect” described the way in which the architect can perceive the evolution of their project with adjustments to information flows through an object-oriented design. In 1975, Eastman established the link between the architectural design of a building and the field of computer science, and then developed and implemented a Building Description System (BDS) that establishes the basis of object modeling through a model that encapsulates different information and their management within the BDS (Eastman 1975), in which the “element” is the basic unit to which information is added.
Today, BIM is one of the major technological innovations in the field of construction, providing a 3D information base for studies and simulations on an urban scale, including environmental studies, energy, noise, property value simulations, etc. BIM allows the characterization of the geometry of buildings, spatial relationships, quantities as well as properties of construction elements, cost, materials, etc. Beyond its contribution to the economy of construction through cost and time optimization, BIM responds to sustainable development through a model that integrates information on the elements of the model for intelligent and sustainable construction. Upon delivery of the building, an “as-built” version of the BIM represents the actual state of the building, which helps facility managers to undertake maintenance and intelligent building management operations.
At an urban scale, GIS (Geographic Information System) is proving to be a powerful system for managing spatial phenomena. It must therefore be aligned with the increased need for rich and well-structured three-dimensional data that can offer advanced functionalities in a 3D space. The problem is not reduced to a simple extension of 2D GIS solutions by adding a third dimension, but requires consistent modeling, representation, storage and 3D spatial analysis for an optimal management of 3D data.
Through the capture, modeling, storage, manipulation, analysis, sharing and representation of geographically referenced data, 3D GIS describes information about the environment as it is captured at different times in a 3D environment. However, it provides access to data that is less detailed than data from BIM, but more up-to-date and covers a wide spatial extent (Worboys and Duckham 2004), therefore giving BIM and 3D GIS two different scales of modeling and analysis.
Trivially, the development of a 3D GIS is motivated by the increased demand for 3D information, and also by the technological revolution in 3D data acquisition, 3D reconstruction and modeling, new 3D visualization techniques such as virtual, augmented or mixed reality, and 3D spatial analysis. The challenge today is to choose the most appropriate technique for modeling a given spatial problem, from a range of 3D acquisition solutions, which is continuously developing and increasingly accessible to (initially) non-expert users. The difficulty lies rather in the implementation of solutions for processing, optimized storage and knowledge extraction from a 3D dataset. Moreover, the quality and integrity of the acquired data are two important parameters to be taken into consideration in the development of 3D models.
BIM-3D GIS integration: A new paradigm for a smart and sustainable urban space
The planning and management of the built environment requires at least two levels of analysis and planning, either at the city or neighborhood scale (GIS) or at the building scale (BIM). An integration of both BIM and 3D GIS models will be beneficial to adapt urban territories to the digital age. The current research trend is towards the integration of approaches from the geographic information domain (3D GIS) and the architectural and engineering domain (BIM). The challenge is to make a multi-scale modeling of urban space.
The result of this integration is GeoBIM, a hybrid process that combines information from the BIM micro-scale (building) and the GIS macro-scale (neighborhood, city, region, etc.). Thanks to its very detailed and precise information on the elements of a building, the BIM feeds the information represented by the GIS; the latter contains more general information and extends to a wider spatial context.
One example of the potential of 3D GIS is its ability to provide a platform for the simulation of urban issues related to the concept of a “Smart City”. If the major issue for politicians today is sustainable construction and the implementation of green strategies for new cities, the upgrading of existing buildings to meet the axes of sustainable development is not to be overlooked. 3D GIS plays a major role in this context. On the other hand, BIM provides very detailed and well-structured information about the building which allows its design, construction, management and operation to proceed in a sustainable and intelligent way.
Faced with a sustained urban dynamic and taking into account economic, social and environmental changes as well as the reforms undertaken, the territories of tomorrow are called upon to develop a capacity for resilience and sustainability capable of meeting the major challenges they face. Thus, the implementation of a new model of development and urban planning that responds to the many challenges of competitiveness, social cohesion, preservation of resources and sustainable development and innovation requires the development of concepts and new approaches to planning and a better integration of opportunities offered by new 3D technologies. The integration of 3D GIS and BIM allows the study of the dynamic relationship between physical and environmental conditions, urban geometry and the properties of each building. Such integration will help achieve smart, resilient and sustainable urban spaces (Niu et al. 2015). Having multi-scale urban models not only helps to meet the current requirements for urban space analysis and management, but also helps meet the future and prospective needs of tomorrow’s cities.
However, there are several conceptual and technical complexities that arise from BIM-3D GIS integration. This is mainly due to dissimilarities between the two domains in terms of spatial scale, level of granularity and detail (LoD), geometry representation methods, storage and access, and semantic dissimilarities. There are three main levels of 3D BIM-GIS integration: data-level integration, application-level integration and model-level integration. This last level is more flexible until one of the two models (BIM or 3D GIS) is extended through its standard to integrate the data and elements of the other model. Another more advanced level of extension is the development of a meta-model that mediates between the two models at a higher conceptual level. In the literature, the contributions in the integration of BIM and 3D GIS are notable, but are far from being able to solve all the technical problems inherent to this integration (Biljecki and Tauscher 2019). This is a niche area of research that is still active.
Interoperability: a major challenge for multi-scale BIM
In the general context of “Data Sciences”, the exchange and sharing of data is unavoidable. Given the heterogeneity of systems, tools and formats, interoperability is recognized as a major challenge in the integration of multi-source data. Interoperability is the ability to ensure that data generated by one user can be correctly interpreted by all other users (Shen et al. 2010). Data interoperability enables reliable and efficient information exchange: it is a prerequisite for effective system integration in a collaborative context. The goal is to eliminate or reduce time-consuming and error-prone manual interventions inherent in the operation or exchange of data between software and users.
Interoperability in 3D urban modeling is the fundamental objective behind the development of the CityGML standard. CityGML is an open data model for the storage and exchange of 3D city models. The objective of the development of CityGML is to achieve a common definition of the basic entities, attributes and
