  We propose an integrated approach to active exploration by exploiting the
Cartographer method as the base SLAM module for submap creation and performing
efficient frontier detection in the geometrically co-aligned submaps induced by
graph optimization. We also carry out analysis on the reachability of frontiers
and their clusters to ensure that the detected frontier can be reached by
robot. Our method is tested on a mobile robot in real indoor scene to
demonstrate the effectiveness and efficiency of our approach.
