Horizon detection plays a vital role in the control system of an aircraft during approach and landing. A new horizon detection algorithm based on virtual and actual information fusion was proposed. Firstly, position and pose data were extracted from GPS/AHRS guidance system, and then the exact slope and estimated equation of horizon were calculated with the help of virtual model. Furthermore, the variance of the region above the horizon was acquired. Finally, precise equation of the horizon was determined using region growing and estimation algorithms. Experiment and visual measurement showed this algorithm can effectively detect horizon under low visibility conditions, and provide much auxiliary information to pilots during approach and landing.
