TF / tf2 Transform Tree

ROS's tree structure for tracking and querying the live transform between every pair of coordinate frames.

TF is ROS's coordinate-transform library; the current version is tf2, originally developed by Tully Foote and others at Willow Garage. A robot carries many coordinate frames — the map, the base, each link, cameras, grippers — and their relative poses change over time. TF organizes these frames into a tree, where every edge is a timestamped transform, published by the relevant node to the /tf (dynamic) and /tf_static (fixed) topics. Any program can then query the transform between any two frames at a given moment — for example, converting an object's coordinates as seen by a camera into the arm's base frame so it can be grasped.

ExampleRunning ros2 run tf2_ros tf2_echo base_link camera_link shows the camera's pose relative to the base; robot_state_publisher automatically publishes the whole arm's TF tree from the URDF and joint angles.

Also called

tf2, TF tree, transform tree

Related

Coordinate Transformation · Coordinate Frame · robot_state_publisher · REP 105 · RViz / RViz2 · Homogeneous Transformation Matrix

Sources

ROS 2 Docs: About tf2
ROS Wiki: tf2