In this paper a complete system is designed and implemented, in which the motion of a quadcopter is stably controlled based on visual feedback and measurements of inertial sensors. We focus on developing a cost effective and easy-to-setup vision system. Active markers were finely designed to improve visibility under various perspectives as well as robustness towards disturbances in the image-based pose estimation. Moreover, position- and heading controllers for the quadcopter were implemented to show the system's capabilities. The performance of the controllers was further improved by the use of inertial sensors of the quadcopter. A closed-loop control system is successfully conducted.