 <mujoco>

    <asset>
        <hfield name="terrain_hfield" nrow="20" ncol="20" size="1 1 1 1" />
    </asset>

    <worldbody>
        <body name="bsphere">
            <joint name="sphere_free" type="free"/>
            <geom name="gsphere" pos="0 0 2" type="sphere" size="0.1" rgba="0.7 0.5 0.3 1" />
        </body>
    </worldbody>

    <worldbody>
        <geom name="geom_hfield1" pos="0 0 1" type="hfield" rgba="0 .9 0 1" hfield="terrain_hfield"/>
    </worldbody>

</mujoco>