“…Studies have focused on the recording of the entire procedure , of the phases (Qi et al, 2006), of the steps (Burgert et al, 2006;Fischer et al, 2005;Lemke et al, 2004), of the activities (Forestier et al, 2012;Meng et al, 2004;Neumuth et al, 2006Neumuth et al, , 2009Neumuth et al, , 2012aNeumuth et al, , 2012bRiffaud et al, 2011) and of the motions (Kragic and Hager, 2003). But efforts have been made in particular on extracting low-level information from the OR: videos (Bhatia et al, 2007;Haro et al, 2012;Klank et al, 2008;Lalys et al, 2012aLalys et al, , 2012bLo et al, 2003;Speidel et al, 2008), audio, position data (Houliston et al, 2011;Katic et al, 2010;Ko et al, 2007;Sudra et al, 2007), hand/tool/surgical staff trajectories Ibbotson et al, 1999;Lin et al, 2006;Miyawaki et al, 2005;Nara et al, 2011;Nomm et al, 2008;Yoshimitsu et al, 2010), information about the presence/absence of surgical tools (Ahmadi et al, 2006;Bouarfa et al, 2010;Padoy et al, 2007) or vital signs (Xiao et al, 2005). Several elements of this low-level information can also be combined (Agarwal et al, 2007;James et al, 2007;Malarme et al, 2010;Padoy et al, , 2010Suzuki et al, 2012;Thiemjarus et al, 2012).…”