unable to get point cloud from /camera/depth/points in rviz

edit

When OpenNI publishes point cloud it sets up frame_id to some prespecified value, but it does not create a real tf frame. The frame_id simply says that points were acquired with respect to that frame.

To check the frame_id of your point cloud use the following command:

$ rostopic echo -n 1 /camera/depth/points/header/frame_id

Then, either manually fill in the value you get to Fixed frame in RViz or define a new tf transformation with static_transform_publisher, for example:

$ rosrun tf static_transform_publisher 0 0 0 0 0 0 /world /openni_rgb_optical_frame 100