Invisible Marking and Tracing of Studs/Joists using UV Marker & Laser Level (durring building)

How to place invisible marks on the wall or ceiling before you place the plasterboard (drywall), so the locations of the Joists or Studs can be easily identified.
That allows you to mount heavy duty shelves, furniture, TV mounts, etc. Alternatively, some electronic detection devices can be used, but sometimes the location wound not be accurate.
Hope that helps :)