Merge data from handheld scanner and terrestrial laser scanner

Why should you combine a terrestrial and a handheld 3D scanner?

Everyone, who has already worked with a terrestrial laser scanner, knows the different challenges. You always have some areas that cannot be captured with a terrestrial laser scanner (such as Leica, Trimble, Z+F or FARO scanner) in consequence of size or limited accessibility of the object to be scanned or for lack of time.

Terrestrial Leica, Trimble, Z+F and FARO laser scanners Terrestrial Leica, Trimble, Z+F and FARO laser scanners

There are two options for scanning these missing areas: The first option is to scan the areas from additional positions. But you often need many positions - this circumstance causes much more work and cannot be realized technically everytime.

The second option is to capture the areas by means of a handheld 3D scanner, such as DPI-8 from DotProduct LLC, and to merge both scanner data sets together in a software (e.g. FARO Scene) afterwards.

Handheld 3D scanner DPI-8 from DotProduct LLCHandheld 3D scanner DPI-8 from DotProduct LLC

Scan procedure using the example of FARO Focus3D and DotProduct DPI-8

The approach for scanning is as follows: We scan the spacious areas by means of a FARO laser scanner using laser scanning targets such as reference spheres or checkerboard targets. To quickly combine data from handheld scanner and terrestrial scanner later, we position three targets - in the best case - in corners or hidden areas that cannot be captured.

During or after scanning process with the terrestrial scanner, we can start capturing with the handheld scanner DPI-8. The scanner needs some minutes to warm-up itself and the sensors. Since there will be no influences of temperature during further operation, significantly precise data will be captured.

Warm-up time of DPI-8 3D scannerWarm-up time of DPI-8 3D scanner

AprilTags for more precise scan results during use of DPI-8

Depending on the size of the area to be captured, the use of additional targets for the handheld scanner DPI-8 might be required. We recommend AprilTags (available for free) offered by DotProduct. The scanning software, which runs directly on the tablet PC, is called Phi.3D. Phi.3D software detects AprilTags automatically during the scanning process.

AprilTags from DotProduct LLCAprilTags from DotProduct LLC

AprilTags are coded 2D targets allowing a clear assignment. After scanning with DPI-8, the scans are automatically registered and can immediately be used on the tablet PC. We can navigate through the scans and already take measurements. Moreover we recommend to define the coordinate system since we can position the point cloud more clearly within the CAD system. However if the point cloud is aligned to an existing model, we can ignore this step.

Point cloud of DPI-8Point cloud of DPI-8

Registration of FARO and DPI-8 scans

For registration of DPI-8 scans together with FARO scans in Scene, there is no need to define the coordinate system. We export the scans in *.pts format - consisting of x value, y value, z value and reflection value. We rename this file *.xyz. Then, we can import the registered DPI-8 data via "drag & drop" into an existing FARO Scene project.

Now, the scans from FARO and DPI-8 scanner can be merged in FARO Scene using the various registration tools.

Export of scan data for post-processing

After having merged all data, we can export the point clouds for use in our desired CAD software such as AutoCAD, Revit, Rhino or MicroStation. Furthermore, we can directly measure in FARO Scene 5.5 and navigate through the point cloud.

Combining two different measurement methods allows us to capture all areas in an economically advantageous way. Although we use two scanners, we can work just in one processing software. That means there is no need for further trainings and we can process projects as usual.