>> 1. I can receive encoder information through odometry messages. My worry
>> is
>> now related to the range i have with URG-04. Is there any work around by
>> which i can overcome the issues of large area?
>
> Buy a longer range laser scanner? What sort of environment will the robot be
> operating in? You mentioned a museum earlier - if that is the case, you may
> not be able to sense very far anyways if the museum becomes crowded even if
> you had 30 meters of range. You could try doing some sort of localization
> with, for example, ceiling lights or other fiducials; basing localization on
> info on the ceiling can be a good idea in a crowded environment as generally
> the view of the ceiling from the robot will be unobstructed.

On that note - if you have the opportunity to put put printed markers
on the ceiling, then you can use a camera to localize yourself. Take a
look at the ar_pose package, as well as the newly developed
camera_pose_estimation.