tutorial-isaac-sim.md

Tutorial for Visual SLAM with Isaac Sim

Overview

This tutorial walks you through a graph to estimate 3D pose of the camera with Visual SLAM using images from Isaac Sim.

Last validated with Isaac Sim 2022.2.1

Tutorial Walkthrough

1. Complete the Quickstart section in the main README.

2. Launch the Docker container using the run_dev.sh script:

   cd ~/workspaces/isaac_ros-dev/src/isaac_ros_common && \
     ./scripts/run_dev.sh

3. Inside the container, build and source the workspace:

   cd /workspaces/isaac_ros-dev && \
     colcon build --symlink-install && \
     source install/setup.bash

4. Install and launch Isaac Sim following the steps in the Isaac ROS Isaac Sim Setup Guide

5. Open up the Isaac ROS Common USD scene (using the Content tab) located at:

   http://omniverse-content-production.s3-us-west-2.amazonaws.com/Assets/Isaac/2022.2.1/Isaac/Samples/ROS2/Scenario/carter_warehouse_apriltags_worker.usd
   

   And wait for it to load completely.

6. Go to the Stage tab and select /World/Carter_ROS/ROS_Cameras/ros2_create_camera_right_info, then in Property tab -> OmniGraph Node -> Inputs -> stereoOffset X change 0 to -175.92.

   

7. Enable the right camera for a stereo image pair. Go to the Stage tab and select /World/Carter_ROS/ROS_Cameras/enable_camera_right, then tick the Condition checkbox.

   

8. Press Play to start publishing data from the Isaac Sim application.

   

9. In a separate terminal, start isaac_ros_visual_slam using the launch files:

   ros2 launch isaac_ros_visual_slam isaac_ros_visual_slam_isaac_sim.launch.py

10. In a separate terminal, send the signal to rotate the robot about its own axis as follows:

    ros2 topic pub /cmd_vel geometry_msgs/Twist '{linear:  {x: 0.0, y: 0.0, z: 0.0}, angular: {x: 0.0,y: 0.0,z: 0.05}}'

11. In a separate terminal, spin up RViz with default configuration file to see the rich visualizations as the robot moves.

    rviz2 -d src/isaac_ros_visual_slam/isaac_ros_visual_slam/rviz/default.cfg.rviz

    

12. To see the odometry messages, in a separate terminal echo the contents of the /visual_slam/tracking/odometry topic with the following command:

    ros2 topic echo /visual_slam/tracking/odometry

    

Saving and using the map

As soon as you start the visual SLAM node, it starts storing the landmarks and the pose graph. You can save them in a map and store the map onto a disk. Make a call to the SaveMap ROS 2 Action with the following command:

Note: /path/to/save/the/map must be a new empty directory everytime you call this action as this action will overwrite the existing contents.

ros2 action send_goal /visual_slam/save_map isaac_ros_visual_slam_interfaces/action/SaveMap "{map_url: /path/to/save/the/map}"

Now, you will try to load and localize in the previously saved map. First, stop the visual_slam node lauched for creating and saving the map, then relaunch it.

Use the following command to load the map from the disk and provide an approximate start location(prior):

ros2 action send_goal /visual_slam/load_map_and_localize isaac_ros_visual_slam_interfaces/action/LoadMapAndLocalize "{map_url: /path/to/save/the/map, localize_near_point: {x: x_val, y: y_val, z: z_val}}"

Once the above step returns success, you have successfully loaded and localized your robot in the map. If it results in failure, there might be a possibilty that the current landmarks from the approximate start location are not matching with stored landmarks and you need to provide another valid value.

Before Localization

After Localization