.. _isaac_sim_app_tutorial_ros_apriltag: =============================== April Tags =============================== Learning Objectives ======================= In this example, we show how to detect April Tags in a scene. **Prerequisites** - Completed :ref:`isaac_sim_app_tutorial_ros_camera` and :ref:`isaac_sim_app_tutorial_ros_tf`. - Install the `apriltag-ros package `_ for April Tag detection. - ``noetic_ws`` was sourced. Detect April Tags ============================= - Open the April Tag example by going to `Isaac Examples -> ROS -> April Tag`. Three April Tags will show up in the viewport. - Open up the Stage Tree, and then open the ActionGraph by right-clicking on the prim and selecting `Open Graph`. The ROS Clock publisher, TF publisher and Camera Helper nodes (for initiating the `camera_info` and `rgb` image publishers) should already be setup. - Press Play to start publishing data to ROS .. figure:: /content/images/isaac_ros_apriltag.png :align: center - In a new terminal with your ROS environment sourced, run ``roslaunch isaac_tutorials apriltag_continuous_detection.launch`` to run the april_tag detection node. - In a new terminal with your ROS environment sourced, run ``rviz -d /src/isaac_tutorials/rviz/apriltag_config.rviz`` to start rviz and show the detections from the camera image - To see the raw data for the detected tags run ``rostopic echo tag_detections`` .. figure:: /content/images/isaac_ros_apriltag_rviz.png :align: center Summary ======================= This tutorial shows the basics of detecting April Tags in |isaac-sim|. Next Steps ^^^^^^^^^^^^^^^^^^^^^^ Continue on to the next tutorial in our ROS Tutorials series, :ref:`isaac_sim_app_tutorial_ros_docker_apriltag` to learn how to run a ROS docker container with |isaac-sim|. Further Learning ^^^^^^^^^^^^^^^^^^^^^^ - More on `April Tags with ROS `_ - If you wish to attach your own April Tag to objects, instructions are in :ref:`isaac_sim_app_asset_april_tag`