He co-developed optimal algorithms for Structure From Motion ( SFM , or Visual SLAM , simultaneous localization and mapping , in Robotics ; Best Paper Award at Conference on Computer Vision and Pattern Recognition 1998 ) , characterized its ambiguities ( David Marr Prize at ICCV 1999 ) , also characterized the identifiability and observability of visual-inertial sensor fusion ( Best Paper Award at Robotics 2015 ) .