The contents of my launch
turtlebot_world.launch----
<launch>
<arg name="gui" default="true"/>
<arg name="world_file" default="$(env TURTLEBOT_GAZEBO_WORLD_FILE)"/>
<arg name="base" value="$(optenv TURTLEBOT_BASE kobuki)"/>
<arg name="battery" value="$(optenv TURTLEBOT_BATTERY /proc/acpi/battery/BAT0)"/>
<arg name="stacks" value="$(optenv TURTLEBOT_STACKS hexagons)"/>
<arg name="3d_sensor" value="$(optenv TURTLEBOT_3D_SENSOR kinect)"/>
<include file="$(find gazebo_ros)/launch/empty_world.launch">
<arg name="use_sim_time" value="true"/>
<arg name="debug" value="false"/>
<arg name="gui" value="$(arg gui)" />
<arg name="world_name" value="$(arg world_file)"/>
</include>
<include file="$(find turtlebot_gazebo)/launch/includes/$(arg base).launch.xml">
<arg name="base" value="$(arg base)"/>
<arg name="stacks" value="$(arg stacks)"/>
<arg name="3d_sensor" value="$(arg 3d_sensor)"/>
</include>
<node pkg="robot_state_publisher" type="robot_state_publisher" name="robot_state_publisher">
</node>
<node pkg="nodelet" type="nodelet" name="laserscan_nodelet_manager" args="manager"/>
<node pkg="nodelet" type="nodelet" name="depthimage_to_laserscan"
args="load depthimage_to_laserscan/DepthImageToLaserScanNodelet laserscan_nodelet_manager">
<remap from="image" to="/camera/depth/image_raw"/>
<remap from="scan" to="/scan"/>
</node>
</launch>