Using Dot stickers is a great idea ,unfortunately not in scanning by using david laser scanner.
David is using the geometry of each scan to align it , it does not recognize dot stickers and they are not big enough to use them as a geometry in alignment
You have to guess that where you will get bad alignment using shape fusion.
And As JDM Dyno and micr0 wrote above You have to add some geometrical shapes (specially Spheres) around or on the part.
In total by adding these spheres , You are changing the geometry of the part to have a nice alignment .
This strategy gives us enough ability to scan large objects easily .
Only add extra geometries on the part , calibrate your scanner and scan the part.
Notice that :
By having a bit error in calibration process you will get more deviation in scanning large objects