This is the demo code show cased at ROSCon 2019 featuring rmw_iceoryx and its zero-copy capabilities.
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.
ros2 run fixed_size_image_transport image_transport_publisher
This sends the default values - VGA image size with 15 Hz.
ros2 run fixed_size_image_transport image_transport_subscriber
Like the publisher, this subscribes to default values of VGA.
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.