Basic advice for positioning a laser scanner
A laser scanner can only measure what is visible from its position (in location and height). Said in a simple way, a laser scanner can only image what the human eye can see as the laser scanner also cannot scan behind corners. It is important to scan an object from various locations in order to receive a complete image as a scan result (point cloud). The more complex the scanned object is, the more measuring points make sense.
How can I avoid horizontal shadowing effects?
Depending on the angle in which the laser scanner is positioned in relation to the surface, inidividual areas behind corners cannot be scanned, e.g. in embrasures. In order to solve this problem, another position is necessary for your laser scanner. The green area in the image shows which areas the laser scanner cannot measure.
With the scanner positioned intellegently in another location, not just the shadowed area of the first scan is scanned. The scanned object is also rescanned a second time, resulting in additional measuring points, a higher point density and a more detailed scan result.
How do I avoid additional vertical shadowing effects?
In choosing the position for your laser scanner, you should also factor in vertical shadowing effects.
Vertical shadowing effects result in gaps in the point cloud. Scanning a frontage just from a higher scanner position, a window ledge might be scanned well while an area above the ledge can be a blind spot. Thus, the laser scanner should be moved to different heights in order to create an image as complete as possible. The complete scan of building features at eye level is possible as well as scanning areas which cannot be recorded from the ground.
This instructional content was provided by laserscanning-europe.com