Hello, I'm a newer to ROS. Now I want to launch a demo in the tutorial describes at "http://www.ros.org/wiki/hector_quadrotor/Tutorials/Quadrotor%20indoor%20SLAM%20demo". I have followed the instructions of the tutorial and build the packages successfully. However, when I launch:

roslaunch hector_quadrotor_demo indoor_slam_gazebo.launch

I get following messages:

fangzheng@ubuntu:~$ roslaunch hector_quadrotor_demo indoor_slam_gazebo.launch
... logging to /home/fangzheng/.ros/log/31f05b12-c194-11e1-b8b0-000c293af122/roslaunch-ubuntu-3605.log
Checking log directory for disk usage. This may take awhile.
Press Ctrl-C to interrupt
Done checking log file disk usage. Usage is <1GB.

started roslaunch server http://ubuntu:57047/

SUMMARY
========

PARAMETERS
 * /use_sim_time
 * /hector_mapping/scan_topic
 * /hector_mapping/advertise_map_service
 * /hector_mapping/update_factor_free
 * /hector_mapping/use_tf_pose_start_estimate
 * /hector_trajectory_server/source_frame_name
 * /hector_mapping/laser_z_min_value
 * /hector_mapping/base_frame
 * /hector_geotiff_node/map_file_base_name
 * /hector_mapping/map_resolution
 * /hector_mapping/laser_z_max_value
 * /hector_mapping/scan_subscriber_queue_size
 * /hector_mapping/update_factor_occupied
 * /robot_state_publisher/tf_prefix
 * /rosdistro
 * /hector_mapping/odom_frame
 * /robot_description
 * /hector_mapping/use_tf_scan_transformation
 * /hector_mapping/map_update_distance_thresh
 * /hector_trajectory_server/trajectory_update_rate
 * /rosversion
 * /hector_mapping/map_start_y
 * /hector_mapping/map_start_x
 * /ground_truth_to_tf/frame_id
 * /hector_mapping/tf_map_scanmatch_transform_frame_name
 * /hector_mapping/map_multi_res_levels
 * /hector_mapping/map_frame
 * /hector_mapping/map_size
 * /robot_state_publisher/publish_frequency
 * /hector_geotiff_node/draw_free_space_grid
 * /hector_geotiff_node/geotiff_save_period
 * /hector_mapping/pub_map_odom_transform
 * /hector_trajectory_server/trajectory_publish_rate
 * /hector_mapping/map_update_angle_thresh
 * /hector_geotiff_node/draw_background_checkerboard
 * /hector_geotiff_node/map_file_path
 * /ground_truth_to_tf/odometry_topic
 * /hector_trajectory_server/target_frame_name

NODES
  /
    gazebo (gazebo/gazebo)
    spawn_robot (gazebo/spawn_model)
    robot_state_publisher (robot_state_publisher/state_publisher)
    ground_truth_to_tf (odometry_to_tf/odometry_to_tf)
    hector_mapping (hector_mapping/hector_mapping)
    hector_trajectory_server (hector_trajectory_server/hector_trajectory_server)
    hector_geotiff_node (hector_geotiff/geotiff_node)
    rviz (rviz/rviz)

ROS_MASTER_URI=http://localhost:11311

core service [/rosout] found
process[gazebo-1]: started with pid [3627]
process[spawn_robot-2]: started with pid [3628]
process[robot_state_publisher-3]: started with pid [3629]
process[ground_truth_to_tf-4]: started with pid [3630]
process[hector_mapping-5]: started with pid [3631]
process[hector_trajectory_server-6]: started with pid [3632]
process[hector_geotiff_node-7]: started with pid [3633]
process[rviz-8]: started with pid [3634]
Gazebo multi-robot simulator, version 0.10.0

Part of the Player/Stage Project [http://playerstage.sourceforge.net].
Copyright (C) 2003 Nate Koenig, Andrew Howard, and contributors.
Released under the GNU General Public License.

[ WARN] [1340938987.643699057]: The root link base_link has an inertia specified in the URDF, but KDL does not support a root link with an inertia.  As a workaround, you can add an extra dummy link to your URDF.
HectorSM map lvl 0: cellLength: 0.05 res x:2048 res y: 2048
HectorSM map lvl 1: cellLength: 0.1 res x:1024 res y: 1024
[ INFO] [1340938988.675249265]: HectorSM p_base_frame_: base_footprint
[ INFO] [1340938988.675705226]: HectorSM p_map_frame_: map
[ INFO] [1340938988.675883822]: HectorSM p_odom_frame_: nav
[ INFO] [1340938988.676049918]: HectorSM p_scan_topic_: scan
[ INFO] [1340938988.676197251]: HectorSM p_use_tf_scan_transformation_: true
[ INFO] [1340938988.676343609]: HectorSM p_pub_map_odom_transform_: true
[ INFO] [1340938988.676540794]: HectorSM p_scan_subscriber_queue_size_: 5
[ INFO] [1340938988.676716708]: HectorSM p_map_pub_period_: 2.000000
[ INFO] [1340938988.676876533]: HectorSM p_update_factor_free_: 0.400000
[ INFO] [1340938988.677023241]: HectorSM p_update_factor_occupied_: 0.900000
[ INFO] [1340938988.677169010]: HectorSM p_map_update_distance_threshold_: 0.400000 
[ INFO] [1340938988.691836584]: HectorSM p_map_update_angle_threshold_: 0.060000
[ INFO] [1340938988.692002727]: HectorSM p_laser_z_min_value_: -1.000000
[ INFO] [1340938988.692151082]: HectorSM p_laser_z_max_value_: 1.000000
[rviz-8] process has died [pid 3634, exit code -11].
log files: /home/fangzheng/.ros/log/31f05b12-c194-11e1-b8b0-000c293af122/rviz-8*.log
directory [/tmp/gazebo-fangzheng-0] already exists (previous crash?)
the owner gazebo server (pid=2266) is not running.
deleting the old information of the directory [/tmp/gazebo-fangzheng-0]
Param [quickStepPreconIters] is deprecated: [replace quickStepPreconIters with stepPreconIters]
Param [quickStep] is deprecated: [replace quickStep with stepType]
Param [quickStepIters] is deprecated: [replace quickStepIters with stepIters]
Param [quickStepW] is deprecated: [replace quickStepW with stepW]
ScopedName[gplane]
ScopedName[willow_map]
ScopedName[point_white]
Gazebo successfully initialized
[ INFO] [1340938992.119554256]: waitForService: Service [/gazebo/set_physics_properties] has not been advertised, waiting...
[ INFO] [1340938992.123836616]: No plugins loaded for geotiff node
[ INFO] [1340938992.123923851]: Geotiff node started
[INFO] [WallTime: 1340938992.536615] [0.039000] waiting for service spawn_urdf_model
[ WARN] [1340938992.593556769, 0.039000000]: multiple inconsistent <turnGravityOff> exists due to fixed joint reduction, overwriting previous value [false] with [true].
[ WARN] [1340938992.600015909, 0.039000000]: multiple inconsistent <turnGravityOff> exists due to fixed joint reduction, overwriting previous value [true] with [false].
ScopedName[quadrotor]
[/tmp/buildd/ros-electric-simulator-gazebo-1.4.15/debian/ros-electric-simulator-gazebo/opt/ros/electric/stacks/simulator_gazebo/gazebo/build/gazebo/server/rendering/OgreVisual.cc:520]
  Unable to get Material[PR2/Blue] for Geometry[Ogre/SceneRoot_VISUAL_288_VISUAL_289_VISUAL_290_VISUAL_294_VISUAL_296. Object will appear white
[ INFO] [1340938993.926807437, 0.039000000]: INFO: gazebo_ros_laser plugin artifically sets minimum intensity to 101.000000 due to cutoff in hokuyo filters.
[ERROR] [WallTime: 1340938994.380928] [0.039000] Service call failed: transport error completing service call: unable to receive data from sender, check sender's logs for details
================================================================================REQUIRED process [gazebo-1] has died!
process has died [pid 3627, exit code -11].
log files: /home/fangzheng/.ros/log/31f05b12-c194-11e1-b8b0-000c293af122/gazebo-1*.log
Initiating shutdown!
================================================================================
[hector_geotiff_node-7] killing on exit
[hector_trajectory_server-6] killing on exit
[hector_mapping-5] killing on exit
[ground_truth_to_tf-4] killing on exit
[robot_state_publisher-3] killing on exit
[spawn_robot-2] killing on exit
[gazebo-1] killing on exit
Traceback (most recent call last):
  File "/opt/ros/electric/stacks/simulator_gazebo/gazebo/scripts/spawn_model", line 330, in <module>
    sm.callSpawnService()
  File "/opt/ros/electric/stacks/simulator_gazebo/gazebo/scripts/spawn_model", line 315, in callSpawnService
    rospy.wait_for_service('/gazebo/unpause_physics')
  File "/opt/ros/electric/stacks/ros_comm/clients/rospy/src/rospy/impl/tcpros_service.py", line 156, in wait_for_service
    raise ROSInterruptException("rospy shutdown")
rospy.exceptions.ROSInterruptException: rospy shutdown
Unhandled exception in thread started by 
Error in sys.excepthook:

Original exception was:
shutting down processing monitor...
... shutting down processing monitor complete
done
fangzheng@ubuntu:~$

The gazebo simulator is shown, however it is shutdown quickly.

I don't know what's the matter.

Is there anybody who can help me.

Many thanks!