Apply normal map shader

edit

I noticed in the SDF specification one can add a <shader> tag with type normal_map_tangentspace to a <material> tag. But when I try to load my world file in gazebo 9 (also tried it in 7), the last output I get in the console is waitForService: Service [/gazebo/set_physics_properties] has not been advertised, waiting.... It will wait forever.

I also made sure that the gazebo_model_path is set up correctly in my package.xml, so the texture file specified in the <normal_map> child tag should get found. It works at least for meshes and material scripts. Here is a snippet from my world file:

    <model name="model">
        <link name="link">               
            <visual name="visual">
                <geometry>
                    <mesh>
                        <uri>model://mesh.dae</uri>
                    </mesh>
                </geometry>
                <material>
                    <shader type="normal_map_tangentspace">
                        <normal_map>model://materials/textures/Normal.png</normal_map>
                    </shader>
                    <script>
                        <uri>model://materials/scripts</uri>
                        <name>Material</name>
                    </script>
                </material>
            </visual>
        </link>
    </model>

Does anyone have experience with this and knows what I'm missing?

Thanks in advance, David