“…They are often used in military or surveillance applications Collins et al, 2000;Cupillard et al, 2003;Fischer et al,2004;Safeguards, 2007), in medicine (Grimson et al, 1998;Bornik et al, 2003;Pandya & Siadat, 2001;Tang et al, 1998;Bernd & Seibert, 2004), entertainment industry (Stapleton et al, 2002;Wren et al, 1997;Huang & Yan, 2002;Collomosse et al, 2003;Fua & Plankers, 2003) or sport (Qiu et al, 2004;Gueziec, 2002;Kristan et al, 2006), for research on human-computer interaction (Sato et al, 2004;Bradley & Roth, 2005;Polat et al, 2003), intelligent environments (Krumm et al, 2000) and similar. Continuous technological development and increasing competition among vendors have led to a great selection of tracking systems that are available on the market today with a variety of capabilities.…”