“…The standard way to estimate 6-DOF rigid transformations, consists in minimizing an energy functional (based on an iconic or geometric matching criterion) often with a continuous optimization algorithm (see section 4.1) where the search space is part of the Euclidean group SE(3) of rigid transformations. Sensors as described in section 2.3 can be used as well for rigid alignment as proposed in a number of papers (Chandler et al, 2008;Elen et al, 2010;Fei et al, 2002Fei et al, , 2003aFrühwald et al, 2009;Fuerst et al, 2014;Gholipour et al, 2010;Huang et al, 2009;Jiang et al, 2007a;Kainz et al, 2015;Kim et al, 1999Kim et al, , 2010aNir and Tannenbaum, 2011;Penney et al, 2004a;Rousseau et al, 2006;Smolíková Wachowiak et al, 2005;Xu et al, 2014b;Yeo et al, 2004;Yu et al, 2011;Chen et al, 2016).…”