Suit
Overview
The vicon suit essentially provides two key elements to the motion tracking process:
Generally the purpose of the suit is as a connection between the markers and the person being tracked - it is used to keep the markers on the body without resorting to gluing or tape. Glue or tape can (and has) been used to keep markers on the body, but in general this is inconvenient.
The other use for the suit is to actually reduce reflection from the body, in general skin reflection isn't very high, but it can in some instances create reflective spots (especially on shiny skin) that is picked up by the cameras.