Not Seeing Robot in rviz
I'm working through the URDF Tutorial and one of the first things to do is to load a example file, 01-myfirst.urdf, into rviz for visualization. So I load the example file as is, run the rviz launch file, rviz opens up, and the rviz grid is empty -- no robot!
I do get a warning message in rviz that says:
No tf data. Actual error: Fixed Frame [map] does not exist
What does this mean? What's missing? Why can't I see the robot?
P.S. I'm running Hydro.