Write a ROS Image Message in Simulink

This example shows how to write an image message and publish it to a ROS network in Simulink®.

Start a ROS network.

rosinit

Launching ROS Core...
Done in 0.38738 seconds.
Initializing ROS master on http://172.23.85.196:49762.
Initializing global node /matlab_global_node_97469 with NodeURI http://dcc3868130glnxa64:33461/ and MasterURI http://localhost:49762.

Load a sample image. Create a subscriber to receive a ROS Image message on the /image topic. Specify the message type as sensor_msgs/Image and the data format as struct.

exampleHelperROSLoadImageData
sub = rossubscriber("/image","sensor_msgs/Image",DataFormat="struct");

Open the Simulink model for writing and publishing ROS Image message.

open_system("write_image_example_model.slx");

Ensure that the Publish block is publishing to the /image topic. Under the Simulation tab, select ROS Toolbox > Variable Size Arrays and verify the Data array has a maximum length greater than the length of the Data field in img (921,600).

The model writes the input img to a ROS Image message. Using a Header Assignment block, the frame ID of the message header is set to /camera_depth_optical_frame.

Run the model to publish the message.

sim("write_image_example_model.slx");

The image message is published to the ROS network and received by the subscriber created earlier. You can use the rosReadImage function to retrieve the image in a format that is compatible with MATLAB®.

imageFormatted = rosReadImage(sub.LatestMessage);

The sample image has an rgb8 encoding. By default, rosReadImage returns the image in a standard 480-by-640-by-3 uint8 format. View this image using the imshow function.

figure
imshow(imageFormatted)

Close the model and shut down the ROS network.

close_system("write_image_example_model.slx",0);
rosshutdown

Shutting down global node /matlab_global_node_97469 with NodeURI http://dcc3868130glnxa64:33461/ and MasterURI http://localhost:49762.
Shutting down ROS master on http://172.23.85.196:49762.