what is the difference between Fixed Frames (top left of rviz window)?
At http://www.ros.org/wiki/openni_launch
3.Quick start
Set the Fixed Frame (top left of rviz window) to /camera_depth_optical_frame.
There are /camera_depth_frame, /camera_depth_optical_frame, /camera_link,
/camera_rgb_frame and /camera_rgb_optical_frame.
what is the difference between /camera_depth_frame, /camera_depth_optical_frame,
/camera_link, /camera_rgb_frame and /camera_rgb_optical_frame.?