Pre-requsites

1. Install all Tb3 packages
2. sudo apt install ros-melodic-slam-gmapping

Gmapping with Turtlebot3

Launch the world and gmapping package

1. roslaunch pursuit_evasion robot_mapping.launch

To drive autonomously with Turtlebot3 to map(not suggested)

2. roslaunch turtlebot3_gazebo turtlebot3_simulation.launch

Using teleop to move around and create map

2. roslaunch turtlebot3_teleop turtlebot3_teleop_key.launch

Saving the created map

3. rosrun map_server map_saver -f ~/map