ir_intensity publishes empty readings in Ignition Gazebo on maze world

[luiznery]

Describe the bug
/ir_intensity messages always contain an empty readings array. Just base_link frame is published.
The strange thing that I noticed is that it just happens in the maze world. In the depot, it works normally.

To Reproduce
Ubuntu 24.04
Ros2 Jazzy

1. Run simulation: ros2 launch irobot_create_gz_bringup sim.launch.py world:=maze
2. Spawn robot: ros2 launch irobot_create_gz_bringup create3_spawn.launch.py spawn_dock:=false use_rviz:=false
3. ros2 topic echo /ir_intensity

Expected behavior
Get readings from the 7 sensors

Screenshots
Location of the robot when the echo was executed.

Additional context
I'm running the simulation and then spawning the robot to avoid a bug about the diffdrive_controller.

When ros2 topic echo /hazard_detection is executed it prints, even thought there is a wall in front of the robot:
header:
stamp:
sec: 918
nanosec: 968000000
frame_id: base_link
detections: []

When I echo other hidden topics, such as _internal/ir_intensity_front_center_right/scan or _internal/ir_intensity_front_center_right I don't get nothing.

This problem is very similar to #209
This previous issue was closed but the problem was not solved and no solution was found.

[basvd]

I encountered the same problem and did a bit of debugging. It seems that ros_gz_bridge is using the wrong topic because the world name does not match up with what Gazebo is using. In Gazebo, the world name (in the topic) is default whereas in the bridge launch file it's maze. For now I simply hard-coded the bridge to use default as the world name, but I haven't looked into the reason for the mismatch.

The other thing I had to change to get the ir_intensity scans to show up in RViz was to add <gz_frame_id>${sensor_name}</gz_frame_id> to the ray_sensor macro. Without it, RViz would complain about message queue being full.

Hope this helps.

[basvd]

The world name is set to default in the maze.sdf file. Changing it to maze there fixes the problem without my previous workaround.