Scene Composition

This section explains how to compose scenes using MuJoCo’s include system and the DexRobot MuJoCo component library.

Basic Structure

A scene XML file consists of several key sections:

  1. Default inclusions

  2. Asset inclusions

  3. World body definitions

  4. Component inclusions

Example Scene

Here’s a complete example (based on box.xml):

<?xml version="1.0" encoding="utf-8"?>
<mujoco model="box">
    <!-- Include defaults first -->
    <include file="../parts/defaults.xml"/>

    <!-- Include required assets -->
    <include file="scene_sim/topfloor_scene.xml"/>
    <include file="furniture_sim/simpleTable/simpleTable_asset.xml"/>
    <include file="../parts/dexhand021_right_floating_asset.xml"/>

    <!-- Define scene hierarchy -->
    <worldbody>
        <!-- Add floating hand -->
        <body name="floating_hand_base" pos="0 0 1.2">
            <include file="../parts/dexhand021_right_floating_body.xml"/>
        </body>

        <!-- Add table -->
        <body name="scenetable" pos="0 0 0" euler="0 0 1.57">
            <include
                file="furniture_sim/simpleTable/simpleMarbleTable_body.xml"/>
        </body>

        <!-- Add manipulatable object -->
        <body name="box" pos="0 0 0.82">
            <inertial pos="0 0 0"
                     mass="0.03"
                     diaginertia="0.00002 0.00002 0.00002"/>
            <geom type="box"
                  size="0.03 0.03 0.03"
                  pos="0 0 0"
                  euler="0. 0. 0."
                  rgba="0.49803922 0.72156863 0.87058824 1"/>
            <freejoint/>
        </body>
    </worldbody>

    <!-- Include remaining hand components -->
    <include file="../parts/dexhand021_right_floating_actuator.xml"/>
    <include file="../parts/dexhand021_right_floating_sensor.xml"/>
    <include file="../parts/dexhand021_right_floating_contact.xml"/>
</mujoco>

Component Types

Defaults

Always include defaults first:

<include file="../parts/defaults.xml"/>

This sets up standard parameters for physics, rendering, and contacts.

Assets

Include all required visual assets:

<!-- Environment -->
<include file="scene_sim/topfloor_scene.xml"/>

<!-- Furniture -->
<include file="furniture_sim/simpleTable/simpleTable_asset.xml"/>

<!-- Hand -->
<include file="../parts/dexhand021_right_floating_asset.xml"/>

Bodies

Add physical bodies to the scene:

<body name="component_name" pos="x y z" euler="r p y">
    <include file="path/to/component_body.xml"/>
</body>

The body tag sets:

  • name: Unique identifier

  • pos: Position [x y z]

  • euler: Orientation [roll pitch yaw]

Additional Components

Include remaining components after worldbody:

<include file="path/to/component_actuator.xml"/>
<include file="path/to/component_sensor.xml"/>
<include file="path/to/component_contact.xml"/>

Building Scenes

Step-by-Step Process

  1. Start with model declaration:

    <?xml version="1.0" encoding="utf-8"?>
<mujoco model="scene_name">

  2. Include defaults:

    <include file="../parts/defaults.xml"/>

  3. Include all required assets:

    <include file="scene_sim/environment.xml"/>
<include file="path/to/component1_asset.xml"/>
<include file="path/to/component2_asset.xml"/>

  4. Define worldbody with components:

    <worldbody>
    <body name="component1" pos="x1 y1 z1">
        <include file="path/to/component1_body.xml"/>
    </body>
    <body name="component2" pos="x2 y2 z2">
        <include file="path/to/component2_body.xml"/>
    </body>
</worldbody>

  5. Include remaining component files:

    <include file="path/to/component1_actuator.xml"/>
<include file="path/to/component1_sensor.xml"/>
<include file="path/to/component1_contact.xml"/>

Common Patterns

Floating Hand Scene

Basic setup for hand manipulation:

<mujoco model="hand_scene">
    <include file="../parts/defaults.xml"/>
    <include file="scene_sim/room_scene.xml"/>
    <include file="../parts/dexhand021_right_floating_asset.xml"/>

    <worldbody>
        <body name="floating_hand_base" pos="0 0 1">
            <include file="../parts/dexhand021_right_floating_body.xml"/>
        </body>
    </worldbody>

    <include file="../parts/dexhand021_right_floating_actuator.xml"/>
    <include file="../parts/dexhand021_right_floating_sensor.xml"/>
    <include file="../parts/dexhand021_right_floating_contact.xml"/>
</mujoco>

Hand-Arm Scene

Setup for mounted hand:

<mujoco model="arm_scene">
    <include file="../parts/defaults.xml"/>
    <include file="scene_sim/room_scene.xml"/>
    <include file="../parts/dexhand021_right_jaka_zu7_asset.xml"/>

    <worldbody>
        <body name="robot_base" pos="0 0 0">
            <include file="../parts/dexhand021_right_jaka_zu7_body.xml"/>
        </body>
    </worldbody>

    <include file="../parts/dexhand021_right_jaka_zu7_actuator.xml"/>
    <include file="../parts/dexhand021_right_jaka_zu7_sensor.xml"/>
    <include file="../parts/dexhand021_right_jaka_zu7_contact.xml"/>
</mujoco>

Next Steps