3D scanning allows you to scan objects from multiple angles to capture the apparent and hidden parts of your object.
The collected data can be combined to create the best possible 3D model.

If you are looking for 3D scanners, look into these:
Artec http://www.artec3d.com/
Structure http://structure.io/

More information can be found here :

http://en.wikipedia.org/wiki/3D_scanner