Target Alignment Guidelines for Laser Scanners

Checkerboard references

• The angle of incidence between the laser beam and the checkerboard reference should not be smaller than 45°.
• Depending on the chosen scanning resolution, the automatic detection of checkerboard references gets unreliable beyond a certain distance to the scanner. E.g. when using A4 checkerboard references and scanning with a resolution of 1/4, the distance to the scanner should not be greater than 15m.
• The distance between the scanner and the references should not be smaller than 1m.
• The checkerboard target should not be rotated by 45° in relation to the scanner’s axis.
• The checkerboard reference should not be attached to a curved surface.
• Print paper references with laser printers only.

Spheres

• The spheres should be completely visible in the scan. Make sure that they are not partly covered by other objects.
• The radius of fit operations in the “Match Sphere Settings” (Tools -> Options -> Matching -> Match Sphere Settings, see 18.1.4.1.8.3) should be set according to the radius of the used spheres in the scan.
• Depending on the chosen scanning resolution, the automatic detection of sphere references gets unreliable beyond a certain distance to the scanner. E.g. when scanning with a resolution of 1/4, the distance to the scanner should not be greater than 18m. The sphere should have at least 10-15 pixels in the scan.

Keywords: sphere, checkerboard, registration, references, objects, alignment, align