The first thing to learn about BIM is its definition. In this session, we will discuss what it is currently defined, the implications in the definition, and its possible evolution in the future. You may find many different but similar definitions from the literature. Here, I would like to use the definitions from Wikipedia in 2014 and 2017 for our discussions. in both the 2014 and 2017 definitions, BIM stands for Building Information Modeling. In the 2014 one, BIM is defined as the process of generating and managing building data during its life cycle, while in the 2017 one, BIM is defined as a process involving the generation and management of digital representations of physical and functional characteristics of places. The same keyword is “process”. The difference is that the 2014 one focuses on just building data but the 2017 one is on digital representations of physical and functional characteristics of places, which include buildings or other built assets. The process [of BIM] produces the Building Information Model (also abbreviated BIM), which encompasses building geometry, spatial relationships, geographic information, and quantities and properties of building components. Also, BIM models are currently stored in file formats which can be extracted, exchanged or networked to support decision-making. It is very important to understand the differences between a CAD model and a BIM model. A 3D CAD model is just a combination of geometric entities such as points, lines, and faces. Unless these entities are grouped and specifically defined, the computer has no idea what the combination of these geometric entities or objects really represent in the real world. But for a BIM model, it is composed of the pre-defined object components that correspond to the real world objects. For example, in a building, we have beams, columns, floors, windows, doors, etc. In the CAD model of the building, only geometric face or surface entities are used to construct the geometry of all these beams, columns, floors, windows, and doors. But in the BIM model, we actually have BIM objects in the digital model that correspond to the beam, column, floor, window, door objects in the physical world. We just use those predefined objects to construct a building model in the computer. In this way, the computer can understand what the components or objects the model has. So the computer can automatically calculate and report the quantities of all these objects for us. Also, we may have information attached to these 3D geometric objects. For example, the colors of and the materials used for these objects. So, a BIM model is more than a CAD model although a BIM model usually looks very similar to a 3D CAD model. The key difference is the information attached to the model components and used by the object-oriented modeling approach. Some people use the term Virtual Engineering to refer to the doing of engineering work in the virtual space or the digital space using the BIM technology. As I said, the current BIM stands for Building Information Modeling. Here, the keyword is information because it is what we care the most in our engineering decision-making process. Some people have started to call BIM as Building Information Management. So you can see it is kind of shifting from the focus on modeling into more on management. Of course, creating a good BIM model is essential in the BIM process before we can manage information using the model. However, information management determines the success of BIM applications and therefore becomes much more important as BIM evolves. Some people even push it further into Building Knowledge Management. So this also remind us that it is not just about information management, but it can actually evolve into the domain of knowledge management for our buildings and built assets. Because originally Building Information Modeling refers more to the modeling and management of the building data. It is true that the technology starts from its applications to building industry. And all tools have been developed for those purposes. As the development of the technology has reached a certain level of maturity for the building industry, we now also apply the technology for modeling and management of infrastructure data or information. So some people use a different terminology, such as Construction Information Modeling or Civil Works Information Modeling, to refer to BIM applications to public infrastructures, such as roads, bridges, tunnels, etc. In the future, it is very likely that we won’t spell out BIM but just use BIM as a technology for modeling and managing information of buildings and all other built assets. Let me summarize the key points before we end this session. The first one is about the current definition of BIM. The keyword is the “process” and the focus is on “Information”. The second point is that BIM is more than 3D CAD. So you need to be able to distinguish a BIM model from a CAD model. And the third point is about the various names of BIM. Because of the BIM technology and its applications are still evolving and expanding, people have started to use different names for different purposes. But in my opinion, in the long round, we will probably just use BIM for all of them.
