Point Cloud to BIM – How we do it
Firstly, what is Point Cloud to BIM?
It is the process of 3D laser scanning of a physical space or site, so we can create a highly accurate digital representation of it. This is then used for design, assessing progress or for evaluating the options a space has. We often use the process when clients need to alter an existing building, but need to keep an established structure in place so need a very accurate representation of the current building.
Capture
During this phase it is important to gather as much information as possible from the client and field about the project, so we can define the Scope of Work and timeline for the project. We will confirm the site conditions and will standardise and create template worksheets to help assure the quality of the final BIM model.
We use the most advanced 3D laser scanners available to capture data in the form of millions of ‘data points’ on a building. The device has an eye-safe laser rotating at a high speed; when it hits a solid surface, it records its position as the data points.
These data points are combined together to form a ‘Point Cloud Scan’ which allows for highly accurate representations of the scan subject, so that it is possible to see the exact dimensions and details of a space.
Process
This involves inspecting the Point Cloud Scan to check for interruptions in the data fluidity. As this could be caused by environmental vibrations, it may not be caught on the internal system checks. For processing, we’ll split the data points into clusters, and if any manipulation is required, we’ll always keep the originals as a back-up.
At the next post-registration stage, it is important to ensure that the alignment of the data is extremely important and is checked through the software and manually.
BIM Modelling
Firstly, the point cloud co-ordinates are verified before the scan is inserted into Revit, the BIM software that we use. If there is more than one Point Cloud file, the integrity and co-ordinates of each file must be assured simultaneously before being locked down to the location.
The Revit file will be set up according to the Scope of Work and level of detail required by the client, including the different building levels and usually a grid system to allow for detailed analysis.
Each element must be modelled as single correct Revit Elements using single column groups and hosted to the corresponding levels with the internal and external walls inserted accurately at the perimeters.
Once the model is set up, we have a quality assurance process involving a number of final checks of different sections of the model, checking for inconsistencies. After the quality assurance process is complete, the model is ready for use, providing an invaluable collaboration tool for complex projects.
Sources: https://www.united-bim.com/walk-through-of-point-cloud-to-bim-process/
