ROS2 Transforms (TF2)

Use tf2_ros::Buffer's lookupTransform with the target frame, source frame, and a time point, wrapped in a try-catch for tf2::TransformException. The result is a geometry_msgs::msg::TransformStamped containing translation and rotation.

Define plain domain entities like Pose with position, orientation, frame_id, and timestamp, plus an ITransformService interface. Implement the interface in the infrastructure layer with tf2_ros so domain use cases never import tf2_ros or geometry_msgs.

Create a tf2_ros::StaticTransformBroadcaster with your node, fill a TransformStamped with parent frame, child frame, translation, and rotation, then call sendTransform. Static transforms are latched and published once.

The exception occurs when the requested frames are not connected in the TF tree, the transform is not yet available at the requested time, or data is older than the buffer cache time, which defaults to about 10 seconds. Always catch it and handle the failure gracefully.

Time(0) returns the latest available transform and is convenient for general lookups. For data synchronization between sensors, use precise timestamps matching the message header so the transform corresponds to the exact measurement time.