ray sensor not publishing points properly

edit

I was trying to visualise velodyne hdl 32 in rviz and the point cloud created by this sensor in rviz, but the output point cloud is not coming realistic, as i've seen it should come like this

but i am visualising the point cloud in rviz like :

First i though that this kind of output is coming because angular velocity of velodyne is less but even after i made it rotate faster, same type of output point cloud comes, so can anyone explain me what is this happening. I am using a ray sensor as laser source for velodyne.

  <gazebo>
    <plugin name="gazebo_ros_control" filename="libgazebo_ros_control.so">
      <robotNamespace>/laser</robotNamespace>
      <robotSimType>gazebo_ros_control/DefaultRobotHWSim</robotSimType>
    </plugin>
  </gazebo>
<gazebo reference="top">
  <sensor type="ray" name="head_hokuyo_sensor">
    <pose>0 0 0.09 1.5708 0 -1.5708</pose>
    <visualize>true</visualize>
    <update_rate>30</update_rate>
    <ray>
     <noise>
      <type>gaussian</type>
      <mean>0.0</mean>
      <stddev>0.1</stddev>
     </noise>
      <scan>
        <horizontal>
          <samples>32</samples>
          <resolution>1</resolution>
          <min_angle>-0.53529248</min_angle>
          <max_angle>0.18622663

</max_angle>
        </horizontal>
      </scan>
      <range>
        <min>0.05</min>
        <max>70</max>
        <resolution>0.02</resolution>
      </range>
    </ray>
    <plugin name="hokuyo_node" filename="libgazebo_ros_laser.so"> <-- or libgazebo_ros_gpu_laser-->
      <topicName>/myrobot1/laser/scan</topicName>
      <frameName>base</frameName>
    </plugin>
  </sensor>

</gazebo>

the ray sensors in gazebo is seen like: I'm using ros indigo with gazebo 7.4. i also tired gpy_ray sensor and block_laser but they didn't worked. My velodyne xacro file:

<?xml version="1.0"?>
<robot name="laser" xmlns:xacro="http://ros.org/wiki/xacro">
<xacro:include filename="$(find myrobot1_description)/urdf/laser.gazebo" />
<xacro:include filename="$(find myrobot1_description)/urdf/materials.xacro" />

  <link name="base">

    <visual>
      <origin rpy="0 0 0" xyz="0 0 0.078335"/>
      <geometry>
        <mesh filename="package://myrobot1_description/meshes/velodyne_base.dae"/>
      </geometry>
      <material name="red"/>
    </visual>

    <collision>
      <origin rpy="0 0 0" xyz="0 0 0.078335"/>
      <geometry>
        <mesh filename="package://myrobot1_description/meshes/velodyne_base.dae"/>
      </geometry>
    </collision>

    <inertial>
      <origin rpy="0 0 0" xyz="0 0 0.078335"/>
      <mass value="0.5"/>
      <inertia ixx="0.000090623" ixy="0.0" ixz="0.0" iyy="0.000090623" iyz="0.0" izz="0.000091036"/>
    </inertial>

  </link>

  <link name="top">
    <visual>
      <origin rpy="0 0 0" xyz="0 0 0"/>
      <geometry>
        <mesh filename="package://myrobot1_description/meshes/velodyne_top.dae"/>
      </geometry>
      <material name="white"/>
    </visual>

    <collision>
      <origin rpy="0 0 0" xyz="0 0 0"/>
      <geometry>
        <mesh filename="package://myrobot1_description/meshes/velodyne_top.dae"/>
      </geometry>
    </collision>

    <inertial>
      <mass value="0.5"/>
      <inertia ixx="0.000090623" ixy="0.0" ixz="0.0" iyy="0.000090623" iyz="0.0" izz="0.000091036"/>
    </inertial>
  </link>

  <joint name="joint1" type="revolute">
    <origin rpy="0 0 0" xyz="0 0 0.077"/>
    <axis xyz="0 0 1"/>
    <limit effort="1000.0" lower="-10000000000000000" upper="10000000000000000" velocity="0.5"/>
    <parent link="base"/>
    <child link="top"/>
  </joint>

  <transmission name="tran1">
    <type>transmission_interface/SimpleTransmission</type>
    <joint name="joint1">
      <hardwareInterface>EffortJointInterface</hardwareInterface>
    </joint>
    <actuator name="motor1">
      <hardwareInterface>EffortJointInterface</hardwareInterface>
      <mechanicalReduction>1</mechanicalReduction>
    </actuator>
  </transmission>

</robot>

I also succesfully used block_lase sensor and plugin but still i ... (more)