ROS2 demo application sending fixed size images

This is the demo code show cased at ROSCon 2019 featuring rmw_iceoryx and its zero-copy capabilities.

Usage

In order to leverage the full potential of zero-copy, we assume in the following that you use rmw_iceoryx_cpp as the underlying RMW implementation. That is, prefixing the commands below by RMW_IMPLEMENTATION=rmw_iceoryx_cpp or generally setting the environment variable in its respective terminal.

The application consists of two executables:

• image_transport_publisher
• image_transport_subscriber

Both executables have to be started with a specific image size to agree on a common topic.

Start the publisher

ros2 run fixed_size_image_transport image_transport_publisher

This sends the default values - VGA image size with 15 Hz.

Start the subscriber

ros2 run fixed_size_image_transport image_transport_subscriber

Like the publisher, this subscribes to default values of VGA.

Modifying the data volume, frequency and transport method

The publisher/subscriber tuple can be modified to send/receive different image sizes with various frequencies and either with loaned messages or classic stack based message allocation.

For this, start the publisher with additional command line arguments as such:

ros2 run fixed_size_image_transport image_transport_publisher <frequency> <image size> <transport method>

The subscriber can then be started as such:

ros2 run fixed_size_image_transport image_transport_subscriber <image_size> [--no-gui]

The --no-gui arguments becomes handy when sending large image sizes to not display them with each callback.