ROS Programming: Building Powerful Robots

The launch files

The launch files in ROS can do multiple tasks in a single file. The launch files have an extension of .launch. The following code shows the definition of start_usb_cam.launch, which starts the usb_cam node for publishing the camera image as a ROS topic:

    <launch> 
      <node name="usb_cam" 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="usb_cam" /> 
        <param name="auto_focus" value="false" /> 
        <param name="io_method" value="mmap"/> 
      </node> 
    </launch> 

Within the <node>...</node> tags, there are camera parameters that can ...