Run/create a first fixed frame with NO_PARENT
Hello and first thanks for reading,
as I'm quite new in ros, and quite completely new in tf package, my problem was the next, I wanted to use tf package to transform a point cloud(with position changing in time) with reference to world(0,0,0). I have seen the tf tutorials, that helps to create frames starting by frames added by turtlesim, and that package creates the firsts frames, so I couldn't be able to understand how it have been done.
So I wanted to create or run the world frame, with NO_PARENT, but I didn't want turtlesim package to do this because it runs 2 nodes more(at least keeping the tutorials of tf: http://www.ros.org/wiki/tf/Tutorials) and I didn't wanted to add rubbish that I would have not used,
would it be possible to just run or add a world frame with no others frames, so I could then add a just the frames I interest??
For putting you in scene I have used a moving "robot" with a gps(using gpsd_client package) and a laser(using hokuyo_node package) fixed on the robot, and I would like to transform the scan point cloud to have every scan done (by laser) with the position(given by gps) where it has been scanned, so I need just 2 frames, the world frame (reference frame, I think it should be the (0,0,0)) and a frame with defines the scan position (with the same position as provided by gps), that would be changing in time according to the robot moves.
As I asked and according to Lorenz recommendations(sorry for before and hope it would be better now), I keep the question edited with question and you will see the answer by Lorenz down this question, that was if someone could help me at least to run or add a simple fixed frame world and I could continue with adding the target moving frame. Althought adding the moving frame should be the difficult and not the world frame, I had found some tutorials to do this that I could try to check, but according to easy question add a fixed world frame, I have not found the solution althought finding a lot.
So if you had the same problem just read now Lorenz answer, if I understood well (still couldn't try it) it's been done automatically when you send any transform, if the parent frame doesn't exist it's been create automatically as a NO_PARENT frame (0,0,0). In any case read his post to better understand.
Excuse my english and again thank you very much for your patience,
special thanks for you Lorenz!
Pablo Payno
