Detects gates as used in the IROS drone races, i.e., square colored gates. It does so with snake gate detection, a computationally efficient method that works onboard of the computationally constrained Parrot Bebop 1/2 drones. An initial version of this algorithm ran in the drone race 2016. The algorithm was first described in: First autonomous multi-room exploration with an insect-inspired flapping wing vehicle, May 2018, IEEE International Conference on Robotics and Automation (ICRA 2018), Brisbane, Australia by Kirk Scheper, Matej Karasek, Christophe De Wagter, Bart Remes, and Guido de Croon https://www.researchgate.net/publication/327228053_First_autonomous_multi-room_exploration_with_an_insect-inspired_flapping_wing_vehicle For the drone race, the algorithm and performance are described in more detail in: Autonomous drone race: A novel vision-based navigation and control strategy, S.Li, M.M.O.I. Ozo, C. De Wagter, G.C.H.E. de Croon. Submitted. video_thread