The Probability Grid As you navigate Cye, you will notice that a white trail -- similar to a wake that a boat creates -- forms behind the robot's icon on the screen. This trail marks the areas that the robot has found to be free of obstacles. Technically speaking, the wake only records the likelihood that any space is clear. Cye's software calculates -- based on what the robot has encountered -- the probability that any given area is free of obstacles. The degree of probability is expressed through the shading of the map on the screen. Areas that Cye has not explored appear as dark gray. Areas that Cye has reason to believe might be clear are light gray. Areas that Cye is more certain about are even less gray. The greater the probability, the whiter the pixel.