  This work deals with a moving target chasing mission of an aerial vehicle
equipped with a vision sensor in a cluttered environment. In contrast to
obstacle-free or sparse environments, the chaser should be able to handle
collision and occlusion simultaneously with flight efficiency. In order to
tackle these challenges with real-time replanning, we introduce a metric for
target visibility and propose a cascaded chasing planner. By means of the
graph-search methods, we first generate a sequence of chasing corridors and
waypoints which ensure safety and optimize visibility. In the following phase,
the corridors and waypoints are utilized as constraints and objective in
quadratic programming from which we complete a dynamically feasible trajectory
for chasing. The proposed algorithm is tested in multiple dense environments.
The simulator AutoChaser with full code implementation and GUI can be found in
https://github.com/icsl-Jeon/traj_gen_vis
