How to debug world file in gazebo? [closed]

edit

My launch file:

  sam@sam:~/code/ros/temp$ cat t1.launch 
  <launch>

    <!-- start gazebo with an empty plane -->
    <param name="/use_sim_time" value="true" />

    <node name="gazebo" pkg="gazebo" type="gazebo" args="$(find ias_gazebo)/worlds/ros_fallschool_day4.world" respawn="false" >
  </node>


  </launch>

My world file:

  sam@sam:~/code/ros/temp$ cat /home/sam/code/ros/cram/ias_gazebo/worlds/ros_fallschool_day4.world
  <?xml version="1.0"?>

  <gazebo:world 
    xmlns:xi="http://www.w3.org/2001/XInclude"
    xmlns:gazebo="http://playerstage.sourceforge.net/gazebo/xmlschema/#gz" 
    xmlns:model="http://playerstage.sourceforge.net/gazebo/xmlschema/#model" 
    xmlns:sensor="http://playerstage.sourceforge.net/gazebo/xmlschema/#sensor" 
    xmlns:window="http://playerstage.sourceforge.net/gazebo/xmlschema/#window" 
    xmlns:param="http://playerstage.sourceforge.net/gazebo/xmlschema/#param" 
    xmlns:body="http://playerstage.sourceforge.net/gazebo/xmlschema/#body" 
    xmlns:geo="http://willowgarage.com/xmlschema/#geo" 
    xmlns:geom="http://playerstage.sourceforge.net/gazebo/xmlschema/#geom" 
    xmlns:joint="http://playerstage.sourceforge.net/gazebo/xmlschema/#joint" 
    xmlns:interface="http://playerstage.sourceforge.net/gazebo/xmlschema/#interface" 
    xmlns:ui="http://playerstage.sourceforge.net/gazebo/xmlschema/#ui"
    xmlns:rendering="http://playerstage.sourceforge.net/gazebo/xmlschema/#rendering" 
    xmlns:renderable="http://playerstage.sourceforge.net/gazebo/xmlschema/#renderable" 
    xmlns:controller="http://playerstage.sourceforge.net/gazebo/xmlschema/#controller"
    xmlns:physics="http://playerstage.sourceforge.net/gazebo/xmlschema/#physics" >

    <verbosity>5</verbosity>

  <!-- cfm is 1e-5 for single precision -->
  <!-- erp is typically .1-.8 -->
  <!-- here's the global contact cfm/erp -->
    <physics:ode>
      <stepTime>0.001</stepTime>
      <gravity>0 0 -9.8</gravity>
      <cfm>0.000000000001</cfm>
      <erp>0.2</erp>
      <quickStep>true</quickStep>
      <quickStepIters>10</quickStepIters>
      <quickStepW>1.3</quickStepW>
      <contactMaxCorrectingVel>100.0</contactMaxCorrectingVel>
      <contactSurfaceLayer>0.001</contactSurfaceLayer>
    </physics:ode>

    <geo:origin>
      <lat>37.4270909558</lat><lon>-122.077919338</lon>
    </geo:origin>

    <rendering:gui>
      <type>fltk</type>
      <size>1024 768</size>
      <pos>0 0</pos>
      <frames>
        <row height="100%">
          <camera width="100%">
            <xyz>2 0 1.5</xyz>
            <rpy>0 20 180</rpy>
          </camera>
        </row>
      </frames>
    </rendering:gui>


    <rendering:ogre>
      <ambient>0.3 0.3 0.3 0.3</ambient>
      <sky>
        <material>Gazebo/CloudySky</material>
      </sky>
      <gazeboPath>media</gazeboPath>
      <grid>false</grid>
      <maxUpdateRate>10</maxUpdateRate>
      <shadowTechnique>stencilAdditive</shadowTechnique>
    </rendering:ogre>

    <!-- clock -->
    <model:physical name="clock">
      <xyz>0 0 0</xyz>
      <rpy>0 0 0</rpy>
      <static>true</static>
      <body:box name="clock_body">
        <geom:box name="clock_geom">
          <mesh>default</mesh>
          <size>0 0 0</size>
          <visual>
            <size>0 0 0</size>
            <material>PR2/White</material>
            <mesh>unit_box</mesh>
          </visual>
        </geom:box>
      </body:box>
      <!-- broadcast ros /time with simTime -->
      <controller:gazebo_ros_time name="gazebo_ros_time" plugin="libgazebo_ros_time.so">
        <alwaysOn>true</alwaysOn>
        <updateRate>1000.0</updateRate>
        <interface:audio name="dummy_gazebo_ros_time_iface_should_not_be_here"/>
      </controller:gazebo_ros_time>
      <!-- offer ROS services to spawn and delete models -->
      <controller:gazebo_ros_factory name="gazebo_ros_factory" plugin="libgazebo_ros_factory.so">
        <alwaysOn>true</alwaysOn>
        <updateRate>1.0</updateRate>
        <interface:audio name="dummy_gazebo_ros_factory_iface_should_not_be_here"/>
      </controller:gazebo_ros_factory>
    </model:physical>

    <!-- ground plane -->
    <model:physical name="gplane">
      <xyz>0 0 0</xyz>  
      <rpy>0 0 0</rpy>
      <static>true</static>

      <body:plane name="plane">
        <geom:plane name="plane">
          <laserRetro>2000.0</laserRetro>
          <mu1>50.0</mu1>
          <mu2>50.0</mu2>
          <kp>1000000000.0</kp>
          <kd>1.0</kd ...