Finding Color Transitions along a Line

For robot self-localization we use the transition of the green playing field to the white walls as features. To detect the borders we have developed a very fast (300000 lines of length 100 pixel) algorithm that finds a predefined color transition along a line. We also use the algorithm when searching for objects (i.e ball, opponents, goals) to discard candidate regions found by the above region growing algorithm. We check for each region whether it has a transition to the green floor (all objects with contact to the floor have this transition, with few exceptions, when an object is located next to a marking line for example). For a more detailed description of the algorithm see [1][3].