Accuracy in BIM-Point Cloud Deviation Analysis
When using 3D scan data on your project, it is important to understand the factors that impact total accuracy:
- Scan Registration
- Scale of Project
- Scan and BIM Alignment
- BIM Accuracy
- Deviation Analysis
Scanners have parameters for expected accuracy from each point as well as confidence intervals for errors and noise in the data. (Please refer to each scanner vendors’ specifications for the details.)
There are a variety of methods & tools for scan data registration. It is common to expect a certain registration error for each scan pair and the total error can be accumulated as more scan data is registered into each other. Please refer to the registration software vendors’ specifications for the details.
Scale of Project
The scale of the project such as the number of scans and total area involved affect global accuracy.
Scan and BIM Alignment
The scan data must be properly aligned to the BIM coordinate system. There are many advanced methods to set up common geometries between scan and BIM data for this purpose. If required CupixWorks provides alignment features that support this process.
An outdated or incorrect BIM can affect the accuracy of the analysis.
Model Level of Detail (LOD)
LOD 100 is not going to be as useful as LOD 400 for deviation analysis because the detail is not available.
Deviation analysis in CupixWorks measures the available surface area between the point cloud and BIM datasets. There is no considerable computation error in the spatial calculation of deviation in CupixWorks software.
To achieve the desired accuracy for your project we recommend choosing a scanning, registration, and alignment process that meets your requirements.