Imerso is a user-friendly platform for detecting and analysing deviations in your construction projects. For optimal analysis results, it helps to understand the difference between unregistered, registered, and merged scans before you upload them to Imerso.
What does "registered" means?
Registering scans is needed when you use stationary scanners (also called TLS - terrestrial laser scanners), such as Leica’s BLK360, RTC360, Trimble X7 or Faro Focus.
Registration is the process of aligning multiple scans to each other. Think of each scan as the piece of a puzzle: The registration process is putting all the pieces of the puzzle together to form a big, coherent picture.
Unregistered Scans:
When scans are not registered, they are like puzzle pieces taken straight out of the box - all over the place and not ordered in relation to each other.
Scans in such a state are not useful for any scans-vs-BIM analysis. Scans need to be registered first in order to be a true representation of the on-site situation.
Registered Scans:
Registered scans are ideal for the scan-vs-BIM analysis in Imerso. The scans have been puzzled together: They are aligned and positioned correctly to each other and form a coherent picture of the onsite status.
The registration process can be done by using the software that came together with the scanner hardware, such as Leica Cyclone, Faro Scene or Trimble RealWorks.
It is also possible to register scans using Imerso (here is the article about the Automatic registration in Imerso). This can be really handy if incorrectly registered scans have been uploaded to Imerso and you find any registration errors later on. Imerso allows you to fix these registration errors directly on the platform - here is the article on how to fix registration errors in Imerso.
💡 For the best experience using Imerso we recommend uploading unmerged registered scans to the platform. Check the best practices section to learn how to do so with the most common point cloud registration software.
Merged Scan:
Instead of stopping at the registration step, some take the process even further and merge the scans together. Merging or unifying scans means to combine all the registered scans into one, massive scan. In our puzzle analogy it would be like taking the finished puzzle and gluing all the pieces together, so nobody would be able to change it.
Merging scans has the advantage of removing overlap between individual scans and potentially minimizing the point cloud size. However, for the scan-vs-BIM analysis, merging scans comes with disadvantages.
⚠️ We recommend to not upload merged scans. When you upload a merged scan to Imerso, it will look the same as a registered point cloud, but there will be some important drawbacks as explained in the next section.
Drawbacks of merged scans
Imerso is able to work with any kind of point cloud uploaded to the platform, but the quality of the uploaded scans directly influences the quality of the results you will get. When it comes to merged scans these are the drawbacks that you'll find:
Most 3D scanners automatically capture 360° pictures as part of the 3D scanning process. These 360° panoramas are used in Imerso for a side-by-side comparison and give you additional context information. If you merge scans, you will lose these 360° panoramas.
If you find an overlooked registration error later on, you won't be able to correct them directly in Imerso. Registration errors do happen, and one shouldn't blindly trust the registration report given by the registration software. If you find a registration error in merged scans, you need to find the original scans on the local PC, fix the registration error in the 3rd party software, re-upload the scans and run the analysis again.
The results of the automatic BIM deviation analysis will be less precise. There will be more false-positives (more elements marked as missing when they are not) and false-negatives results (more elements marked as within tolerance when they are not).
You won't be able to remove noisy points from view or analysis, nor will you be able to download, isolate or move-to individual scans.
Merging the scans moves the origin of the point cloud and the origin will often lay outside of the point cloud. This makes it harder to work with the scan orbs.
Mobile Scanners and the Navvis VLX.
Mobile scanners capture the environment while you are moving (often called SLAM Scanners), such as the Navvis VLX or Leica’s BLK2GO.
All mobile scanners will give you a merged point cloud as an output and most will have the drawbacks mentioned above. The exception are scans from the Navvis VLX; they remain unaffected by the mentioned drawbacks as long as panoramas are included in the export.
💡 If you are using Navvis VLX, please read this article on how to export the scans from IVION to get the best analysis results.