Building Information Modelling (BIM) is for the most part associated with the design and construction phase of the project delivery process. We are becoming familiar with adopting methodologies which tell us how to collate, store, exchange and deliver data in a controlled way, as described in project information requirements.
The same processes can be extended to parts of the industry that manage the capture of existing asset conditions.
One example of where this could be applied is 3D laser scanning, which provides us with a highly accurate, 3-dimensional representation of a captured condition at a specific point in time (a point cloud).
The application of point clouds offers an extremely accurate digital record as the basis for developing project designs and supporting refurbishments, renovations or extensions. However, the possibilities don’t end there. 3D laser scanning and photogrammetry can be used for monitoring purposes, asset management or structural and site inspections. It is also widely used in agriculture, ecology, archaeology and heritage.
If we scan the same feature periodically we acquire datasets capturing the same objects at different points in time. By overlaying these point clouds we can identify areas that have changed indicating for example, structural movements or service failure.
Similarly, point clouds can be a powerful indicator of habitat changes and species movements, crop health, underground water resources and the direction of their flow. 3D laser scans obtained from UAV (LiDAR, photogrammetry, thermal imaging) can be used for insulation performance assessment, subterranean fire detection, solar panels assessment, leak detection, powerline failure detection and so on. Depending on the method of obtaining the data we can acquire different volumes and quality of data for different uses.
In order for the project delivery process to be collaborative we need to think about how we are going to store, exchange and deliver data generated by 3D laser scanning; these are large datasets comprising multiple point clouds each of which can exceed 10GB. The Common Data Environment capacity, network connection and the speed of data transfer play a significant part in this.
It is also important to consider the point cloud density and the requirement for RGB value (colour definition, i.e. Red, Green, Blue), while crucial questions also need to be answered if this process is going to be successful. These include:
- What is the model going to be used for?
- Which features are required to be modelled and to what level of detail?
- Are surface changes and materials to be reflected in the model?
In the previous BIM blog release, we learned about the Model Production and Delivery Table (MPDT). We also discovered that the scope of works is driven by the Employers Information Requirements. This should give us a good understanding of how important it is to consider what the potential model uses are going to be and what level of detail and level of information is required at which data drop. This helps us determine the requirements for scanning resolution and RGB value.
Modelling of specific architectural, structural or MEP features may require higher point cloud density and RGB value, providing modellers with sufficient contrast and detail. However, the density and colour definition of 3D laser scans will impact on the size of point clouds, time spent on site and thus the cost of 3D scan procurement. It is therefore very important to find the right balance, understanding the model uses prior to the start of scanning works.
Considerable investments are associated with 3D laser scanning (equipment, site possessions and safety measures, software and hardware specifications, network capacity for data archiving and exchange, qualifications and skillsets of personnel). To make sure true value is achieved, all data needs to be regularly maintained and updated. Naming conventions must be followed to avoid duplication or loss of data.
Comprehensive publications have just been released by Historic England - dedicated specifically to 3D laser scanning and BIM in relation to the context of heritage. These are available for download here.
Associate Professor, University of Nottingham