The following are the main configurations required for building a global costmap. The definition of the costmap parameters are dumped in chefbot_bringup/param/ global_costmap_params.yaml. The following is the definition of this file and its uses:

global_costmap: 
   global_frame: /map 
   robot_base_frame: /base_footprint 
   update_frequency: 1.0 
   publish_frequency: 0.5 
   static_map: true 
   transform_tolerance: 0.5 

The global_frame here is /map, which is the coordinate frame of the costmap. The robot_base_frame parameter is /base_footprint; it is the coordinate frame in which the costmap should reference as the robot base. The update_frequency is frequency at which the cost map runs its main update loop. The publishing_frequency of the cost map is given as publish_frequency, which is 0.5. If we are using an existing map, we have to set static_map as true, otherwise as false. The transform_tolerance is the rate at which the transform has to perform. The robot would stop if the transforms are not updated at this rate.