Short answer is that you currently can't do exactly what you're saying.
The easiest way to get around it is to create a second link with an appropriate offset, connected with a fixed joint.
This does create an extra frame which will need to be published. This is most often handled with robot_state_publisher.
Originally posted by David Lu with karma: 10932 on 2013-02-21
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Comment by TommyP on 2013-02-21:
I suppose I will get one extra frame per geomtry I want to have. I was afraid that would give possible delays but maybe it will work. I will test it. SO if I used tix joints I can use robot_state_publisher. I assume I could also just have no joints and just publish the frames from my program.
Comment by David Lu on 2013-02-21:
robot_state_publisher is a little wonky, I think, in that it will only publish tfs when it gets joint state messages, so you may also need joint_state_publisher.
Comment by Claudio on 2013-02-21:
Joint state is not needed if you only have static links.
It is necessary with dynamic links.