ROS 2 Lyrical Luth · Lesson 35 of 86

Building custom worlds: warehouse, office and outdoor

Writing SDF worlds, including models, lights, physics and reusing model libraries.

Estimated time · 60–90 min

Learning goals

What you will understand

Explain building custom worlds: warehouse, office and outdoor in your own words
Use it in a small robotics example
Verify the result instead of assuming it worked

Understand the idea first

The mental model

A world file lists a physics configuration, lights and models. Build a warehouse with static shelves and walls, an office with corridors and doors, or an outdoor scene with ground and obstacles. Use <include> to pull ready-made models from Gazebo Fuel instead of modelling everything.

Keep worlds small at first (rendering and physics cost grows with objects), make static things <static>true</static>, and set a realistic physics step (max_step_size 0.001–0.004 s). Save worlds in a package and set GZ_SIM_RESOURCE_PATH so models are found.

Guided lesson

Work through these steps

1.
Source the ROS 2 Lyrical environment in a fresh terminal.
2.
Read the building custom worlds: warehouse, office and outdoor example and identify what each line does.
3.
Build only the affected package, source the workspace overlay, and run the example.
4.
Inspect the result from a second terminal with the ros2 CLI or RViz2 and compare it with the expected result.

Worked example

Read it before you run it

<sdf version="1.9"><world name="warehouse">
<!-- A new world named warehouse. -->
  <physics type="ode"><max_step_size>0.004</max_step_size></physics>
<!-- Physics steps of 4 ms. -->
  <include><uri>model://ground_plane</uri></include>
<!-- Reuse a standard ground plane model. -->
  <include><name>shelf_1</name><uri>model://shelf</uri><pose>3 0 0 0 0 0</pose></include>
<!-- Place a shelf 3 m along X. -->
  <model name="wall_north"><static>true</static><pose>0 5 1 0 0 0</pose><link name="l"><collision name="c"><geometry><box><size>10 0.2 2</size></box></geometry></collision><visual name="v"><geometry><box><size>10 0.2 2</size></box></geometry></visual></link></model>
<!-- A static 10 m wall. -->
</world></sdf>
<!-- End of the world. -->

What the example is doing

1.The ros2 commands query the running graph; they do not prove that a node's internal behavior is correct.
2.Build from the workspace root, then source install/setup.bash so the shell can discover the new package.
3.Use a second sourced terminal to inspect nodes and interfaces while the example runs.

Watch it run · Mobile robot

See what this code does

The terminal types this lesson's practice solution and runs it. The scene shows the kind of robot behaviour that code drives. It plays by itself and loops.

Practice code

Now type it yourself

Copy the starter into your ROS 2 package, replace every TODO, then build with colcon build and run it from a sourced terminal.

<sdf version="1.9">
  <world name="warehouse">
    <include><uri>model://ground_plane</uri></include>
    <!-- TODO: include a shelf model named shelf_1 at position x = 3, y = 0 -->
  </world>
</sdf>

Expected output

The warehouse world opens with one shelf

Stuck? Show the full solution (try it yourself first)

<sdf version="1.9">
  <world name="warehouse">
    <include><uri>model://ground_plane</uri></include>
    <include><name>shelf_1</name><uri>model://shelf</uri><pose>3 0 0 0 0 0</pose></include>
  </world>
</sdf>

Expected result

How you know it worked

ROS_DISTRO is lyrical in every terminal used for the exercise.
The complete package from the exercise builds and the expected graph entity appears in a second terminal.

Practical exercise

Apply the lesson

Build a 10 m × 10 m warehouse world with four walls and three shelves, place your robot inside, drive to each shelf, and create a second, outdoor world with ground and five obstacles.

Before you continue

ROS_DISTRO reports lyrical in every terminal you used
The example builds and runs without errors
You checked the result with a ros2 command, RViz2 or a test, not just by reading the code

If something goes wrong

ros2 cannot find a package or executable.

Source /opt/ros/lyrical/setup.bash, build from the workspace root, then source install/setup.bash in that terminal.

Nodes run but cannot discover each other.

Confirm both terminals use Lyrical, the same ROS_DOMAIN_ID, and compatible network/discovery settings.