hi all. i have two Microsoft webcams that use for stereo mapping and localization with rtabmap. my launch file for run these camera and use rtabmap is this:

<launch>

<arg name="rtabmapviz" default="true" />
<group ns="stereo">

  <node name="left" pkg="usb_cam" type="usb_cam_node" output="screen" >
    <param name="video_device" value="/dev/video0" />
    <param name="image_width" value="640" />
    <param name="image_height" value="480" />
    <param name="pixel_format" value="yuyv" />
    <param name="camera_frame_id" value="left" />
    <param name="io_method" value="mmap"/>
    <param name="camera_info_url" value="file:////home/zahra/Desktop/stereo/left.yaml"/>
  </node>


  <node name="right" pkg="usb_cam" type="usb_cam_node" output="screen" >
    <param name="video_device" value="/dev/video1" />
    <param name="image_width" value="640" />
    <param name="image_height" value="480" />
    <param name="pixel_format" value="yuyv" />
    <param name="camera_frame_id" value="right" />
    <param name="io_method" value="mmap"/>
    <param name="camera_info_url" value="file:///home/zahra/Desktop/stereo/right.yaml"/>
  </node>

<node name="stereo_image_proc" pkg="stereo_image_proc" type="stereo_image_proc" output="screen"  >

<remap from="/stereo/left/image" to="/stereo/left/image_raw"/>
<remap from="/stereo/right/image" to="/stereo/right/image_raw"/>
    <param name="prefilter_size"            value="35"/>
        <param name="prefilter_cap"             value="11"/>
        <param name="correlation_window_size"   value="41"/>
        <param name="min_disparity"             value="-15"/>
        <param name="disparity_range"           value="128"/>
        <param name="uniqueness_ratio"          value="0.0"/>
        <param name="texture_threshold"         value="1000"/>
        <param name="speckle_size"              value="500"/>
        <param name="speckle_range"             value="16"/>
        <param name="approximate_sync"          value="true"/>
        <param name="queue_size"                value="5"/>
</node>

</group>

<node name="stereo_cam" pkg="image_view" type="stereo_view" output="screen" >
<param name="queue_size" value="2000" />
<param name="approximate_sync" value="True" />
<remap from="/stereo/left/image" to="/stereo/left/image_raw"/>
<remap from="/stereo/right/image" to="/stereo/right/image_raw"/>
</node>

<!-- rotate camera so z axis is up and x forward. -->
   <arg name="pi/2" value="1.5707963267948966" />
   <node pkg="tf" type="static_transform_publisher" name="camera_base_link" args="0 0 0 -$(arg pi/2) 0 -$(arg pi/2) camera_link stereo/left 100" /> 

<group ns="rtabmap">   

      <!-- Stereo Odometry -->   
      <node pkg="rtabmap_ros" type="stereo_odometry" name="stereo_odometry" output="screen">
         <remap from="left/image_rect"       to="/stereo/left/image_rect"/>
         <remap from="right/image_rect"      to="/stereo/right/image_rect"/>
         <remap from="left/camera_info"      to="/stereo/left/camera_info"/>
         <remap from="right/camera_info"     to="/stereo_camera/right/camera_info"/>

    <param name="approx_sync"                   type="bool"     value="true"/>
        <param name="frame_id"                      type="string"   value="camera_link"/>
        <param name="odom_frame_id"                 type="string"   value="odom"/>
        <param name="queue_size"                    type="int"      value="5"/>
    </node>

<!-- Visual SLAM: args: "delete_db_on_start" and "udebug" -->
      <node name="rtabmap" pkg="rtabmap_ros" type="rtabmap" output="screen" args="--delete_db_on_start">
         <param name="frame_id"         type="string" value="camera_link"/>
         <param name="subscribe_stereo" type="bool" value="true"/>
         <param name="subscribe_depth"  type="bool" value="false"/>

         <remap from="left/image_rect"   to="/stereo/left/image_rect_color"/>
         <remap from="right/image_rect"  to="/stereo/right/image_rect"/>
         <remap from="left/camera_info"  to="/stereo/left/camera_info"/>
         <remap from="right/camera_info" to="/stereo_camera/right/camera_info"/>
     <remap from="odom" to="/rtabmap/odom"/>

        <param name="approx_sync"                   type="bool"     value="true"/>
        <param name="queue_size"                    type="int"      value="30"/>

</node>

<!-- Visualisation RTAB-Map -->
      <node if="$(arg rtabmapviz)" pkg="rtabmap_ros" type="rtabmapviz" name="rtabmapviz" args="-d $(find rtabmap_ros)/launch/config/rgbd_gui.ini" output="screen">
         <param name="subscribe_stereo"    type="bool" value="true"/>
         <param name="subscribe_odom_info" type="bool" value="true"/>
         <param name="queue_size"          type="int" value="10"/>
         <param name="frame_id"            type="string" value="camera_link"/>

         <remap from="left/image_rect"  to="/stereo/left/image_rect_color"/>
         <remap from="right/image_rect"  to="/stereo/right/image_rect"/>
         <remap from="left/camera_info"  to="/stereo/left/camera_info"/>
         <remap from="right/camera_info" to="/stereo/right/camera_info"/>
         <remap from="odom_info" to="/rtabmap/odom_info"/>
        <remap from="odom" to="/rtabmap/odom"/>

        <param name="frame_id"                      type="string"   value="true"/>
        <param name="queue_size"                    type="int"      value="10"/>

        <param name="subscribe_stereo"              type="bool" value="true"/>
        <param name="subscribe_odom_info"           type="bool" value="true"/>
    </node>
</group>



</launch>

but the launch file wasn't run and error is: [ WARN] [1509489284.298859011]: /rtabmap/stereoodometry: Did not receive data since 5 seconds! Make sure the input topics are published ("$ rostopic hz mytopic") and the timestamps in their header are set. /rtabmap/stereoodometry subscribed to (approx sync): /stereo/left/imagerect, /stereo/right/imagerect, /stereo/left/camerainfo, /stereocamera/right/camerainfo

can anyone help me?!