Traditional CAD drawing modeling primarily relies on 2D planes, whereas BIM modeling is based on 3D foundations. There are fundamental differences between these two approaches. Today, we will explore the key distinctions between CAD modeling and BIM modeling.
When a BIM model is imported into a project, the drawing process differs significantly from the traditional 2D drawing method. In 2D drawing, the smallest unit is a line. Multiple closed lines form a plane, which is then used to represent the building’s appearance, sections, and detailed drawings. Importantly, these lines have no inherent relationship with one another.
In contrast, BIM technology operates on a 3D basis and is presented as a database. A database functions like an electronic filing cabinet, allowing users to add, retrieve, update, or delete data efficiently. This model is both relational and object-oriented. BIM integrates various building components into a single visual database. Each component contains rich parameter information such as size, type, material, and numbering. Users can customize these parameters based on their roles, project requirements, and specific needs.
Because of the conceptual differences between 2D and BIM modeling, many users feel uncertain when transitioning their tools. Often, users apply old 2D concepts and logic to BIM, assuming it is merely a new modeling tool. However, this mindset may prevent them from fully leveraging BIM’s capabilities. To effectively use BIM, one must first understand the model-building process unique to BIM technology. This understanding enables better application and expansion of BIM in projects.
The integration of BIM technology into projects typically occurs in two phases: during design and during construction. Since the timing and roles differ, the model-building process varies accordingly. For instance, this discussion focuses on a project that implements BIM during the construction phase. Here, the construction team takes the architectural drawings from the design team without engaging in the design process and builds the BIM model directly based on those drawings.
Establishing a BIM project model involves three main stages and nine specific steps. The stages are: setting standards, building models, and applying models. The nine steps include:
- Setting project goals
- Defining information requirements
- Establishing relevant supporting standards (during the standard setting stage)
- Collaborative modeling operations (during the model building stage)
- Analysis
- Report export
- Construction drawing output
- 4D process simulation
- Collision detection (during the model application stage)
We will not delve deeper into the differences between CAD and BIM modeling here. This overview aims to provide a clear introduction to help you better understand the transition and benefits of BIM technology.
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