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Ok so I try to answer your questions. I dont have very good english so I hope you will understand.

1 When you load your urdf on a parameter server and then you run robot state publisher. It could create transformations for your robot. You dont need to create broadcaster. Robot state publisher will take as a parameter your robot_description and use it for creating transforms

2 This tutorial has nothing to do with mapping. It just shows and explains trasnformations. In the first part you create broadcaster which broadcasts transformation between base_laser and base_link. Then you choose arbitrary point in coordinate system of base_laser and transform it to coordinate system of base_link. And thats all, transformation represents orientation and translation in space. For better understanding I recommended you to watch this video https://www.youtube.com/watch?v=rTN4nawkrZs . Transformation is global concept used everywhere in robotics graphics and so on not just in ROS.

3 I dont know if you understand the issue but this topic http://docs.ros.org/api/sensor_msgs/html/msg/LaserScan.html represent and defines a data from laser scan. TF is just used to locate laser_base in space relative to the robot_base.

Last thing. Feel free to ask I am beginner too and I also don't understand everything. Year before when I began with ros I had same questions as you. I know my explanation is also not the best but I hope it helps.

Ok so I try to answer your questions. I dont have very good english so I hope you will understand.

1 When you load your urdf on a parameter server and then you run robot state publisher. It could create transformations for your robot. You dont need to create broadcaster. Robot state publisher will take as a parameter your robot_description and use it for creating transformstransformatins

2 This tutorial has nothing to do with mapping. It just shows and explains trasnformations. In the first part you create broadcaster which broadcasts transformation between base_laser and base_link. Then you choose arbitrary point in coordinate system of base_laser and transform it to coordinate system of base_link. And thats all, transformation represents orientation and translation in space. For better understanding I recommended you to watch this video https://www.youtube.com/watch?v=rTN4nawkrZs . Transformation is global concept used everywhere in robotics graphics and so on not just in ROS.

3 I dont know if you understand the issue but this topic http://docs.ros.org/api/sensor_msgs/html/msg/LaserScan.html represent and defines a data from laser scan. TF is just used to locate laser_base in space relative to the robot_base.

Last thing. Feel free to ask I am beginner too and I also don't understand everything. Year before when I began with ros I had same questions as you. I know my explanation is also not the best but I hope it helps.

Ok so I try to answer your questions. I dont have very good english so I hope you will understand.

1 When you load your urdf on a parameter server and then you run robot state publisher. It could create transformations for your robot. You dont need to create broadcaster. Robot state publisher will take as a parameter your robot_description and use it for creating transformatinstransformations

2 This tutorial has nothing to do with mapping. It just shows and explains trasnformations. In the first part you create broadcaster which broadcasts transformation between base_laser and base_link. Then you choose arbitrary point in coordinate system of base_laser and transform it to coordinate system of base_link. And thats all, transformation represents orientation and translation in space. For better understanding I recommended you to watch this video https://www.youtube.com/watch?v=rTN4nawkrZs . Transformation is global concept used everywhere in robotics graphics and so on not just in ROS.

3 I dont know if you understand the issue but this topic http://docs.ros.org/api/sensor_msgs/html/msg/LaserScan.html represent and defines a data from laser scan. TF is just used to locate laser_base in space relative to the robot_base.

Last thing. Feel free to ask I am beginner too and I also don't understand everything. Year before when I began with ros I had same questions as you. I know my explanation is also not the best but I hope it helps.

Ok so I try to answer your questions. I dont have very good english so I hope you will understand.

1 When you load your urdf on a parameter server and then you run robot state publisher. It could create transformations for your robot. You dont need to create broadcaster. Robot state publisher will take as a parameter your robot_description and use it for creating transformations

2 This tutorial has nothing to do with mapping. It just shows and explains trasnformations. In the first part you create broadcaster which broadcasts transformation between base_laser and base_link. Then you choose arbitrary point in coordinate system of base_laser and transform it to coordinate system of base_link. And thats all, transformation represents orientation rotation and translation in space. For better understanding I recommended you to watch this video https://www.youtube.com/watch?v=rTN4nawkrZs . Transformation is global concept used everywhere in robotics graphics and so on not just in ROS.

3 I dont know if you understand the issue but this topic http://docs.ros.org/api/sensor_msgs/html/msg/LaserScan.html represent and defines a data from laser scan. TF is just used to locate laser_base in space relative to the robot_base.

Last thing. Feel free to ask I am beginner too and I also don't understand everything. Year before when I began with ros I had same questions as you. I know my explanation is also not the best but I hope it helps.