A robot for marking an encoded surface is provided. The encoded surface has coded data identifying a plurality of locations thereon. The robot has an image sensor for sensing the coded data, and a processor for generating indicating data using the coded data sensed by the image sensor. The indicating data has data regarding a position of the robot on the encoded surface. The robot uses a communication means to transmit the indicating data to a computer system and receiving instructions from the computer system. A steerable drive system moves the robot over the encoded surface in response to movement instructions received from the computer system and a marking device selectively marks the encoded surface in response to marking instructions received from the computer system.