Running 2 different cameras using usb_cam
<launch>
<group ns="camera1">
<node name="usb_cam1" 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="mjpeg" />
<param name="camera_frame_id" value="yuyv" />
<param name="io_method" value="mmap"/>
</node>
<node name="image_view_1" pkg="image_view" type="image_view" respawn="false" output="screen">
<remap from="image" to="/camera1/usb_cam1/image_raw"/>
<param name="autosize" value="true" />
</node>
</group>
<group ns="camera2">
<node name="usb_cam2" pkg="usb_cam" type="usb_cam_node" output="screen" >
<param name="video_device" value="/dev/video2" />
<param name="image_width" value="640" />
<param name="image_height" value="480" />
<param name="pixel_format" value="mjpeg" />
<param name="camera_frame_id" value="yuyv" />
<param name="io_method" value="mmap"/>
</node>
<node name="image_view_2" pkg="image_view" type="image_view" respawn="false" output="screen">
<remap from="image" to="/camera2/usb_cam2/image_raw"/>
<param name="autosize" value="true" />
</node>
</group>
</launch>
https://answers.ros.org/question/218573/running-2-different-cameras-using-usb_cam/