Most people in the space of digital documentation of buildings claim to create a BIM from a point cloud. But, do they? Through my clients, I have audited many as-built models. A large percentage of them are labeled as “BIM”. However, to my surprise, they are nothing more than glorified Sketchup models developed in Revit.
To create a true Building Information Model, it needs to support the BIM process. Generally, the as-built model is one of the first models created on a project and a repository of information that is further developed into a design model. If the model does not meet clear process-driven specifications, it can create more documentation and production problems for the client than it solves.
So, what does it take for an as-built model to be considered a BIM? It needs to meet the following requirements:
Adhere to the client’s BIM standards
The goal is to develop a product that is on par or better than what can be produced by the client’s internal team. That means you need to adopt the client’s naming conventions, shared and project parameter names, object styles, LOD matrixes, material properties, project and family templates, and modeling guidelines.
Position and orientation of the model
Although this may not be the first thing that comes to mind when thinking about the BIM process, setting the model correctly will help the BIM process down the road - the BIM Manager will thank you for it. If possible, geolocate the model, set an optimal orientation to favor the drawings’ layout, and locate the origin of the model relative to a physical feature (i.e. the bottom-left corner of the building).
Optimize for model performance
Remember, creating the as-built model constitutes the first step in a “messy” creative design process. Hence, you need to develop a product that has minimal warnings and contains content that won’t negatively affect the performance of the model down the road.
Parametric components
Parametrize building components that need to be flexible and adapt to geometrical or appearance variations. Keep parameters to a minimum and use simple formulas. By adopting a solid family development strategy you positively contribute to the performance of the model.
Balance accuracy and usability
Meeting a specified accuracy level while maintaining the as-built model's usability (i.e. levelness, plumbness, and orthogonality) can be challenging. Have a clear understanding of what matters more for the design team: accuracy or usability. If you need to deviate from the maximum level of accuracy to keep elements level, plumb, or orthogonal, have a clear way of communicating such conditions.
Metadata
Include critical or relevant information about the object, within family instances, that is otherwise not obvious: damage, deflection, other remarks, make and model, and specifications. This information will help inform future decisions, reporting, and creating component schedules.
Conclusion
Creating a true as-built BIM requires adherence to process-driven specifications, including client BIM standards, positioning and orientation, model performance optimization, parametric components, and metadata inclusion. Failure to meet these requirements can create more problems than solutions for clients.
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