The orange ball, and the blue and yellow team markers appear as colored dots of about constant size in the image. The form of these dots is not always circular, since moving objects are captured by the camera at different positions for different half images. This causes significant differences between the odd and even image lines. The lighting and the ball shape of the objects produces highlights and shadows. However, most of the pixels belonging to an object have similar colors.
We model the ball and the team marker with its position and size, as well as its color in HSI space. In addition to the team marker, we put two colored dots on top of our robots, such that they form a line from the left to the right wheel (refer to Figure 1 for a top down view). These dots are modeled in the same way as the ball and the team markers.
The robot model contains also information about the distance of the dots and the orientation of the line. For the tracking of other team's robots we have further models with only one or two dots. We initialize the models by clicking with the mouse on the dots and we assign an ID to each of our robots.