I thought best-practice was to use `ros::Time(0)` in `waitForTransform`/`lookupTransform`, not `ros::Time::now()`.  Unless it's really critical that you get the transforms from an exact timestamp (which I don't think is the case here.. these should be static transforms).  See [here](http://wiki.ros.org/tf/Tutorials/Writing%20a%20tf%20listener%20%28C%2B%2B%29).