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Substrate supports loading robot and environment models from URDF and SDF files, browsing the Gazebo Fuel model repository, and spawning models directly into a running simulation.

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Loading from File

Open any .urdf or .sdf file from the file explorer. Substrate parses the model description — links, joints, visual meshes, and collision geometry — and renders it in the 3D Viewer panel.

URDF

Universal Robot Description Format. The standard for ROS-based robot descriptions. Substrate renders visual meshes, joint axes, and link frames from the URDF tree.

SDF

Simulation Description Format. Used by Gazebo for both robot models and world files. Substrate supports SDF models, lights, and physics properties.
Supported mesh formats within model descriptions include STL, DAE (Collada), and OBJ. Mesh file paths are resolved relative to the model file’s location.

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Gazebo Fuel Browser

The Model Browser panel provides access to the Gazebo Fuel model library, which contains thousands of community-contributed and officially maintained 3D models.
1

Open the Model Browser

Open the Model Browser panel from the left sidebar, or use the Command Palette and search for “Model Browser”.
2

Browse local or remote models

By default, the panel displays models from your local Fuel cache. Toggle Remote to search the Gazebo Fuel API directly. Type a search query to filter results — search is debounced so results update as you type.
3

Spawn into simulation

Click any model in the browser to spawn it into the running Gazebo simulation. The model appears at the world origin and is immediately visible in the 3D Viewer.
Spawned models appear at the world origin. Use the transform gizmo to reposition them — select the model in the 3D Viewer, then drag the translation handles to move it to the desired location.

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Local Cache

Models downloaded from Gazebo Fuel are cached on disk at ~/.gz/fuel/. The Model Browser scans this cache directory automatically and displays cached models without requiring a network connection. This means that models you have previously used in Gazebo — whether through Substrate or the command line — are immediately available in the browser.
The Fuel cache follows Gazebo’s standard directory layout:
~/.gz/fuel/
└── fuel.gazebosim.org/
    └── <owner>/
        └── models/
            └── <model-name>/
                └── <version>/
                    ├── model.sdf
                    └── meshes/
Each model version is stored independently, and Substrate reads the latest available version by default.
To free disk space, you can safely delete directories within ~/.gz/fuel/. The Model Browser will update its listing on the next scan. Models will be re-downloaded from Fuel if you need them again.
Spawning a model requires an active Gazebo simulation. If no simulation is running, the Model Browser displays models for preview only. Launch a simulation from the SITL Launcher panel to enable spawning.