NIAMH O’REILLY and EUGENE McGOVERN explain how the integration of geomatics and building information modelling can enhance planning and management of buildings.
Building information modelling (BIM) is a maturing process used to generate and manage data about buildings during their entire life cycle. BIM is a tool that facilitates the flow of information within a project to create a better understanding between the various stakeholders. Collaboration between stakeholders is essential to ensure that the building model can be shared and maintained throughout its complete life cycle, from breaking ground to demolition. This will ensure that data needs only to be entered into the model once but is available to a wide range of stakeholders throughout the life cycle of the project. The alternative is disparate silos of construction and facility management information where accessing up-to-date, accurate information can be problematic, leading to duplication of information, disconnected workflows and a decrease in productivity.
The concept of BIM is now being extended to include existing buildings, historic buildings (HBIM) and infrastructure projects (IBIM). Around the world, government initiatives are driving the ever-increasing adoption of BIM and a number of highly developed software packages now exist. As facilities are designed in the context of their surroundings, a geospatial aspect is introduced, and geographical information systems (GIS) become significant. In the future, BIM and GIS will either converge or will operate in parallel, with high levels of interoperability.
Building information modelling
There is a common misconception that BIM is solely software used for the generation of 3D models. Although these models provide building visualisations, their true potential goes much further and, if developed correctly in a collaborative way, BIM is capable of providing valuable on-demand information to ensure efficient construction and facilities management of the building throughout its complete life cycle.
The real strength of BIM lies in the ‘information’ aspect of the model, which is maintained throughout the life cycle and includes not just geometry but specification properties, quantities together with contract, and personnel and maintenance information. The information is maintained and updated throughout the entire life cycle.
The role of geomatics in BIM
Geomatics professionals play an expert role in the provision of accurate spatial data for the model, from the initial pre-planning stage right throughout the life cycle, a function far beyond the map-making traditions of the past. Professional geomatic surveyors can contribute location-specific information to BIM. Our role has gone from one of information handler to a situation where we now expertly manage vast quantities of spatially referenced data using state of the art GIS. The following outlines the areas of expertise of the GS.
3D model generation
The creation of 3D models is not a new concept to geomatic surveyors, who have been creating these models since the 1970s when the development of the electronic theodolite combined with electronic distance measurement (EDM) devices used in conjunction with electronic data recorders, made it possible to capture highly accurate digital models of ground surfaces and structures in 3D (X, Y, Z) co-ordinates. Their creation was simplified and accelerated with the availability of CAD. Since its inception, CAD has developed and changed from a purely graphical 3D package to one where data-rich models can be generated.
3D laser scanning has become an industry standard for providing accurate measurements at high levels of detail of as-built conditions inside buildings. Laser scanning instruments rapidly record up to one million measuring points per second; the end result is a point cloud, which provides an organised digital model of the building, quickly, efficiently and accurately. The model can be directly imported into CAD packages that have a point cloud engine. Alternatively, the point cloud is converted into a 3D BIM model using specific post-processing software to extract the model from the point cloud, which can then be easily and seamlessly integrated into existing workflows.
These scans are ideally suited to both refurbishment and retrofit projects where complex information about the existing building must be modelled. In addition, throughout the construction stage of the development laser scans can be taken at regular intervals to create a series of point clouds, which can be added to the BIM and assist in the ongoing design.
Production of accurate topographic models
Accurate topographical information showing the topography of the landscape, together with the extent of the site and all services on or close to the site, and with access information, are a fundamental building block for developing the BIM and will form the basis of all subsequent information being added to the model. The term ‘garbage in garbage out’ (GIGO) is used frequently when considering the reliability of the BIM model; it is therefore essential that an accurate topographic model is used when designing the new development, otherwise problems relating to its reliability may arise in the future.
In the future, BIM should be geo-referenced to allow data sharing between the GIS world and the BIM world, which will facilitate record retrieval over longer periods of time. Some existing IBIM software already makes this linkage possible, as BIM capability has been added to long-standing integrated modules for CAD and GIS.
Setting out of the proposed works
In the case of new builds, setting out is required using BIM-generated data. The aim is to transfer the designed structure onto the ground in the correct position (X, Y) and at the correct height (Z). As the development proceeds on site, the geomatic surveyor will make additional measurements for checking purposes. This information will be fed into the BIM to assist in further design and clash detection, and also to form the basis of the as-built survey required upon completion of the project. It is at this stage that the importance of having an accurate large-scale ground model upon which the design was based will be fully appreciated.
Geographical information systems and BIM
GIS are a set of tools used for collecting, storing, retrieving, transforming and displaying spatial data about the real world. In order to achieve this goal, an abstract model of the real world is generated in the GIS, enabling complex real world planning and management problems to be solved using spatial analysis tools. These tools have the capability to answer questions, and create simulations and what-if scenarios by linking features and phenomena on the Earth’s surface to their locations.
The model generated is a data-rich model where all included objects have properties and spatial relationships, which are essential for any spatial analysis. The integration of GIS and BIM provides enormous opportunities to increase efficiencies in certain application areas, such as urban and landscape planning, architectural design, 3D cadastre and environmental simulations. In addition, building-specific information from the BIM can be integrated with GIS information to be used in a wider spatial context for queries and GIS analysis for emergency response and other infrastructure assessment needs. This exchange of BIM and GIS data is possible using web services and open standards, and allows buildings to be related to their spatial geo-referenced location so that both datasets can be overlaid. Potential benefits of this include being able to analyse the impact of the building in its proposed location at design stage. Additional information about the surrounds of the site can also be used in the design process, such as zoning, planning, population density and geological information. This information is readily available and can be included in these overlays to enable more informed decision making at design stage. When brought into a GIS environment, BIM data is suitable for spatial analysis where BIM and GIS data can be overlaid. Where GIS analysis and/or integration are required, then the geomatics professional will have a central role.
Collaboration throughout the project life cycle is founded on open standards of interoperability and requires that all stakeholders are able to share and manage information easily. Currently there are a number of proprietary BIM software packages available on the market, each specialising in a particular field and creating their own proprietary database format. Consequently, there is a need to convert these files into a common format, which can be read in any system. The primary organisation working on interoperability is buildingSMART International, which has published a common file format called IFC (industry formation classes), which enables information sharing and interoperability of intelligent digital building models. The current problems of interpolation between data sources produced from different proprietary software are not restricted to BIM, but have also been encountered with GIS. The resulting problem of data silos leading to duplication of datasets held by large government agencies has led to a number of EU initiatives, including the establishment in 1994 of the Open Geospatial Consortium (OGC), an international voluntary consensus standards organisation, and EU directives such as the INSPIRE directive and the reusability directive. One of the current key objectives of the OGC is to develop publicly viable interface specifications to support interoperable solutions that ‘geo-enable’ data used in the web, GIS and BIM. Such location intelligence, via web mapping, is the next milestone in geospatial information management.
They have been responsible for developing an industry-wide standard City GML for GIS users, which allows for the seamless integration of GIS datasets. They have extended their role and are now currently looking at ways to convert IFC to CityGML Geography Markup Language. This will play an important role in bridging urban information models with BIMs to improve interoperability among information systems used in the design, construction, ownership and operation of buildings and capital projects.
Currently only limited BIM is being used for facilities management; however, the potential is vast and in the future BIM will become more commonplace. Facilities management requires the sort of intelligent data contained in BIM and the adoption of BIM can result in improved space management, streamlined maintenance, efficient use of energy, economic retrofits and renovations, and enhanced life cycle management. The Geomatics Surveyor can provide an accurate, highly detailed model of the final build, using laser scanning techniques. The addition of attribute information about the building together with data already stored about the model will transform this into a data-rich intelligent model, which is a powerful tool for facilities management. Additionally, the integration of this model into a GIS will allow complex problems and scenarios to be modelled to answer ‘what if’ questions.
It is clear that BIM and geomatics are firmly inter-linked – and that the advancement of BIM relies, in part, on integrating geomatics skills and technologies into BIM solutions. A BIM would be useless without the input of correct geospatial data, i.e., accurate data, all in the same coordinate system. The use of the data would also be restricted if good visualisation was not available. Geospatial data is provided for BIM in many forms, including ground survey, photogrammetry and LiDAR. BIM should be seen as a management tool for the complete life cycle of a structure, potentially within its environment, and geomatics professionals can provide the expertise to promote and develop this concept.