local costmap without sensors?

edit

I'm having some problems tuning the local planner on my robot, so I'm trying to simulate in rviz without sensor data.

how do I populate the local costmap with obstacles from the global costmap?

my params look like this right now:

costmap_common.yaml:

obstacle_range: 2.5
raytrace_range: 3.0
footprint: [[ 0.15,  0.15], [-0.15,  0.15], [-0.15, -0.15], [ 0.15, -0.15]]
inflation_radius: 0.30

global_costmap.yaml:

global_costmap:
  global_frame: map
  robot_base_frame: base_link
  update_frequency: 5
  publish_frequency: 1
  static_map: true

local_costmap.yaml:

local_costmap:
  global_frame: odom
  robot_base_frame: base_link
  inflation_radius: 0.3
  update_frequency: 5
  publish_frequency: 2
  static_map: false
  rolling_window: true
  width: 3
  height: 3
  resolution: 0.03
  plugins:
    - {name: static_layer,            type: "costmap_2d::StaticLayer"}
    - {name: inflation_layer,     type: "costmap_2d::InflationLayer"}

but the local costmap is empty so the robot tries to go through obstacles