In the previous lecture, we have learned how to configure our logical camera plugin.  Now, we will learn how to use the data the logical camera produces.

The logical camera outputs models and poses of objects. The poses contain position and orientation information which are defined in the reference frame of the camera. This information is published as a ROS Topic:

$ rosmsg show hrwros_gazebo/LogicalCameraImage.msg -r
$ rosmsg show hrwros_gazebo/Model

The model message type has a string placeholder for the model name and a pose of the model itself.

ROS Topic contents:

Print poses of the objects seen by the logical camera:
$ rostopic echo /hrwros/logical_camera

Note: This command will not work for you yet because you will have to install and configure the logical cameras first by doing Assignment1. Then, you will be able to echo the topics you have configured. By the way, you can already complete the entire Assignment1 already without watching the rest of the videos!

The command publishes the models detected by the logical camera with the corresponding pose information.

In the model sdf files, we define model names that will be used by the logical camera to publish the name information. The logical camera plugin can be configured to only publish objects that are known. But we will not do this.