Arbitrarily colored ball detection using the structure tensor technique

In this paper we present a new technique for ball detection in the RoboCup environment. The proposed method is an advanced version of the Hough transform and its main detection feature is local rotational invariance. This feature is utilized by means of the structure tensor technique, which optimizes linear parameters in partial differential equations within a local neighborhood. For our application we use the vanishing angular derivative describing the rotational invariance of the ball. Since no color information is used, the method can be used for the detection of any arbitrarily colored ball using a vision system. Compared to the standard version of the Hough transform for circle detection our version is a lot more robust, because the structure tensor technique directly provides the circles’ center coordinates as well as the radii and the accumulator space is only used to improve accuracy.