README.md

Bridge communication between ROS and Ignition Transport

This package provides a network bridge which enables the exchange of messages between ROS and Ignition Transport.

The bridge is currently implemented in C++. At this point there's no support for service calls. Its support is limited to only the following message types:

ROS type	Ignition Transport type
std_msgs/Bool	ignition::msgs::Boolean
std_msgs/ColorRGBA	ignition::msgs::Color
std_msgs/Empty	ignition::msgs::Empty
std_msgs/Int32	ignition::msgs::Int32
std_msgs/Float32	ignition::msgs::Float
std_msgs/Float64	ignition::msgs::Double
std_msgs/Header	ignition::msgs::Header
std_msgs/String	ignition::msgs::StringMsg
geometry_msgs/Quaternion	ignition::msgs::Quaternion
geometry_msgs/Vector3	ignition::msgs::Vector3d
geometry_msgs/Point	ignition::msgs::Vector3d
geometry_msgs/Pose	ignition::msgs::Pose
geometry_msgs/PoseArray	ignition::msgs::Pose_V
geometry_msgs/PoseStamped	ignition::msgs::Pose
geometry_msgs/Transform	ignition::msgs::Pose
geometry_msgs/TransformStamped	ignition::msgs::Pose
geometry_msgs/Twist	ignition::msgs::Twist
mav_msgs/Actuators (not on Noetic)	ignition::msgs::Actuators
nav_msgs/OccupancyGrid	ignition::msgs::OccupancyGrid
nav_msgs/Odometry	ignition::msgs::Odometry
rosgraph_msgs/Clock	ignition::msgs::Clock
sensor_msgs/BatteryState	ignition::msgs::BatteryState
sensor_msgs/CameraInfo	ignition::msgs::CameraInfo
sensor_msgs/FluidPressure	ignition::msgs::FluidPressure
sensor_msgs/Imu	ignition::msgs::IMU
sensor_msgs/Image	ignition::msgs::Image
sensor_msgs/JointState	ignition::msgs::Model
sensor_msgs/LaserScan	ignition::msgs::LaserScan
sensor_msgs/MagneticField	ignition::msgs::Magnetometer
sensor_msgs/NavSatFix	ignition::msgs::NavSat
sensor_msgs/PointCloud2	ignition::msgs::PointCloudPacked
tf_msgs/TFMessage	ignition::msgs::Pose_V
visualization_msgs/Marker	ignition::msgs::Marker
visualization_msgs/MarkerArray	ignition::msgs::Marker_V

Run rosmaster & rosrun ros_ign_bridge parameter_bridge -h for instructions.

Example 1a: Ignition Transport talker and ROS listener

First we start a ROS roscore:

# Shell A:
. /opt/ros/noetic/setup.bash
roscore

Then we start the parameter bridge which will watch the specified topics.

# Shell B:
. ~/bridge_ws/install/setup.bash
rosrun ros_ign_bridge parameter_bridge /chatter@std_msgs/String@ignition.msgs.StringMsg

Now we start the ROS listener.

# Shell C:
. /opt/ros/noetic/setup.bash
rostopic echo /chatter

Now we start the Ignition Transport talker.

# Shell D:
ign topic -t /chatter -m ignition.msgs.StringMsg -p 'data:"Hello"'

Example 1b: ROS talker and Ignition Transport listener

First we start a ROS roscore:

# Shell A:
. /opt/ros/noetic/setup.bash
roscore

Then we start the parameter bridge which will watch the specified topics.

# Shell B:
. ~/bridge_ws/install/setup.bash
rosrun ros_ign_bridge parameter_bridge /chatter@std_msgs/String@ignition.msgs.StringMsg

Now we start the Ignition Transport listener.

# Shell C:
ign topic -e -t /chatter

Now we start the ROS talker.

# Shell D:
. /opt/ros/noetic/setup.bash
rostopic pub /chatter std_msgs/String "data: 'Hi'" --once

Example 2: Run the bridge and exchange images

In this example, we're going to generate Ignition Transport images using Gazebo classic, that will be converted into ROS images, and visualized with rqt_viewer.

First we start a ROS roscore:

# Shell A:
. /opt/ros/noetic/setup.bash
roscore

Then we start Gazebo.

# Shell B:
gazebo

Once Gazebo is running, click on the Insert tab, and then, insert a Camera object into the scene. Now, let's see the topic where the camera images are published.

# Shell C:
ign topic -l | grep image
/default/camera/link/camera/image

Then we start the parameter bridge with the previous topic.

# Shell D:
. ~/bridge_ws/install/setup.bash
rosrun ros_ign_bridge parameter_bridge /default/camera/link/camera/image@sensor_msgs/Image@ignition.msgs.Image

Now we start the ROS GUI:

# Shell E:
. /opt/ros/noetic/setup.bash
rqt_image_view /default/camera/link/camera/image

You should see the current images in rqt_image_view which are coming from Gazebo (published as Ignition Msgs over Ignition Transport).

The screenshot shows all the shell windows and their expected content (it was taken using ROS Kinetic):