Comment by d for Do you have a map already or do you want to build a complete map of your environment? In the latter case, you could try the exploration module from: http://wiki.ros.org/nav2dIt completely explores an unknown environment and builds a map using 2D Laser-Scanner.

is there a ROS package that supports autonomous map building? for example, we can just place the robot in a room and it begins to build the map by itself vs. teleop control.