A time-encoded approach to detect cooperative targets for UAV landing

To detect visible light cooperative targets during UAV landing, we use a time relay to encode the intensity of lamps. The change pattern of the lamps intensity is presented in this paper. The frames with strong and weak lamps light are called strong frames weak frames respectively. In continuous sequence images, we take weak frames as background and subtract background using strong fames. The geometric transformations are considered when subtracting background and a float threshold value are used to threshold the difference images. We also design several geometric constraints to eliminate interference points. The approaches to find the first weak frames and to track lamps in a sequence images are also presented. The experiments show that our method is robust to scale change, interference points and moving object in background.