Salvador Barrera Hiroki Takahashi Masayuki Nakajima Hands-Free Navigation Methods for Moving through a Virtual Landscape Walking Interface Virtual Reality Input Devices. 388-394 2004 conf/cgi/2004 Computer Graphics International http://csdl.computer.org/comp/proceedings/cgi/2004/2171/00/21710388abs.htm db/conf/cgi/cgi2004.html#BarreraTN04