On Sun, 2010-12-05 at 20:04 -0800, Prasad Dixit wrote: 
> Hello Bill Moris,
> 
> This is in continuation of my last post: ( I was not able to update the same
> thread in spite of re posting )
> I am reposting it for your reference.
> http://ros-users.122217.n3.nabble.com/ar-pose-basic-questions-td2016877.html#a2018958
> 
> The current scenario is:
> I could able to get /camera at some initial runs.
> Now, i am not able to get the /camera frame in rviz.
> When i start Camera display i get Status error as:
> No CameraInfo received on [/usb_cam/camera_info].  Topic may not exist.
> Image: No image received.
> Transform [Sender=/usb_cam] = For frame [camera]: Frame [camera] does not
> exist
> 
> I executed rosrun usb_cam usb_cam_node
> 
> Then,
> my launch file as:
> 
> <launch>
>  
> 
>         <node pkg="rviz" type="rviz" name="rviz"/>
>            
>    <node pkg="tf" type="static_transform_publisher" name="world_to_cam"
>      args="1 1 0.3 0 0 0 world ar_marker 10" />
>   <node name="ar_pose" pkg="ar_pose" type="ar_single" respawn="false"
> output="screen">
>    </node>
> </launch>
> 
> Where my /usb_cam/cameraInfo topic is being published properly with all
> parameters specified default in usb_cam
> Is there anything i am missing?


Have you calibrated the camera? Does image_proc rectify the image?