Tutorial for NITROS Bridge with Isaac Sim
=================================================

Overview
------------

This tutorial will walk you through how to use :ir_repo:`isaac_ros_nitros_bridge <isaac_ros_nitros> <isaac_ros_nitros_bridge>` to move images on the GPU while avoiding CPU memory copies from Isaac Sim.

Tutorial Walkthrough
--------------------

1. Clone ``isaac_ros_common`` repository under a new workspace:

  .. code:: bash

    mkdir -p ~/isaac_sim_workspaces && \
    cd ~/isaac_sim_workspaces && \
    git clone :ir_clone:`<isaac_ros_common>`
  
2. Install and launch Isaac Sim under the Isaac Sim workspace following the steps in the :doc:`Isaac ROS Isaac Sim Setup Guide </getting_started/isaac_sim/index>`

3. Press **Play** to start publishing data from the Isaac Sim.

  .. note::
    
    You should be able to see, using the command ``ros2 topic list``, two topics under the same main name, one for the standard ROS 2 `sensor_msgs/Image <https://github.com/ros2/common_interfaces/blob/humble/sensor_msgs/msg/Image.msg>`__ (e.g.: ``/front_stereo_camera/left/image_rect_color``) and another for :ir_repo:`isaac_ros_nitros_bridge_interfaces/NitrosBridgeImage <isaac_ros_common> <isaac_ros_nitros_bridge_interfaces/msg/NitrosBridgeImage.msg>` (e.g.: ``/front_stereo_camera/left/image_rect_color/nitros_bridge``).

4. Complete the step 3 & 4 from ``Set Up Development Environment`` section and ``Build from Source`` section following the ``isaac_ros_nitros_bridge_ros2`` quickstart :ref:`here <repositories_and_packages/isaac_ros_nitros/isaac_ros_nitros_bridge/index:quickstart>`.

  
5. Inside the container, change the ``ptrace`` scope to be able to run the NITROS Bridge:

  .. code:: bash

    echo 0 | sudo tee /proc/sys/kernel/yama/ptrace_scope
  
6. Inside the container, edit the :ir_repo:`isaac_ros_nitros_bridge_image_converter.launch.py <isaac_ros_nitros> <isaac_ros_nitros_bridge/isaac_ros_nitros_bridge_ros2/launch/isaac_ros_nitros_bridge_image_converter.launch.py?ref_type=heads#L39>` ROS 2 launch file to remap the ``ros2_input_bridge_image`` to the Isaac Sim's NITROS Bridge topic name (e.g.: ``/front_stereo_camera/left/image_rect_color/nitros_bridge``). Then, run the following command to start the NITROS Bridge.

  .. code:: bash

    cd /workspaces/isaac_ros-dev && \
      source install/setup.bash && \
      ros2 launch isaac_ros_nitros_bridge_ros2 isaac_ros_nitros_bridge_image_converter.launch.py pub_image_name:=nitros_pub sub_image_name:=nitros_sub

7. The converted NITROS image will be available under the ``nitros_pub`` topic.