How to convert *.urdf.xacro files to *.sdf for gazebo?

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Dear all,

as with the latest gazebo version (1.7.12-s1367893033~precise) in groovy, it seems that our *.urdf.xacro files are finally not supported anymore.

I found out about the latest .sdf format (1.3) and already tried to update some of our files. I.e. I replaced

  <xacro:macro name="sick_s300_laser_gazebo_v0" params="name ros_topic update_rate min_angle max_angle">
    <gazebo reference="${name}_link">
      <sensor:ray name="${name}">
        <rayCount>541</rayCount>
        <rangeCount>541</rangeCount>
        <laserCount>1</laserCount>

        <origin>0.0 0.0 0.0</origin>
        <displayRays>false</displayRays>

        <minAngle>${min_angle*180.0/M_PI}</minAngle>
        <maxAngle>${max_angle*180.0/M_PI}</maxAngle>

        <minRange>0.05</minRange>
        <maxRange>30.0</maxRange>
        <resRange>0.03</resRange>
        <updateRate>${update_rate}</updateRate>
        <controller:gazebo_ros_laser name="gazebo_ros_${name}_controller" plugin="libgazebo_ros_laser.so">
          <gaussianNoise>0.005</gaussianNoise>
          <alwaysOn>true</alwaysOn>
          <updateRate>${update_rate}</updateRate>
          <topicName>${ros_topic}</topicName>
          <frameName>/${name}_link</frameName>
          <interface:laser name="gazebo_ros_${name}_iface" />
        </controller:gazebo_ros_laser>
      </sensor:ray>
      <material value="IPA/LightGrey" />
    </gazebo>
  </xacro:macro>

with

  <xacro:macro name="sick_s300_laser_gazebo_v0" params="name ros_topic update_rate min_angle max_angle">
    <gazebo reference="${name}_link">
    <sensor name="${name}" type="ray">
        <ray>
            <scan>
                <horizontal>
                    <samples>541</samples>
                    <resolution>1.0</resolution>
                    <min_angle>${min_angle*180.0/M_PI}</min_angle>
                    <max_angle>${max_angle*180.0/M_PI}</max_angle>
                </horizontal>
            </scan>
            <range>
                <min>0.05</min>
                <max>30.0</max>
                <resolution>0.03</resolution>
            </range>
        </ray>
    </sensor>       

      <material value="IPA/LightGrey" />
    </gazebo>
  </xacro:macro>

for the urdf.xacro files for one of our sensors.

However, if I then spawn our robot, I get the following message from gazebo:

fxm@sony-fxm:/opt/ros/groovy/stacks/simulator_gazebo/gazebo_worlds/worlds$ roslaunch gazebo_worlds empty_world.launch 
... logging to /home/fxm/.ros/log/320cbf70-bca0-11e2-9ff7-00271039ca78/roslaunch-sony-fxm-20823.log
Checking log directory for disk usage. This may take awhile.
Press Ctrl-C to interrupt
Done checking log file disk usage. Usage is <1GB.

started roslaunch server http://sony-fxm:55478/

SUMMARY
========

PARAMETERS
 * /rosdistro
 * /rosversion
 * /use_sim_time

NODES
  /
    gazebo (gazebo/gazebo)
    gazebo_gui (gazebo/gui)

auto-starting new master
process[master]: started with pid [20837]
ROS_MASTER_URI=http://localhost:11311

setting /run_id to 320cbf70-bca0-11e2-9ff7-00271039ca78
process[rosout-1]: started with pid [20850]
started core service [/rosout]
process[gazebo-2]: started with pid [20864]
process[gazebo_gui-3]: started with pid [20876]
Gazebo multi-robot simulator, version 1.5.0
Copyright (C) 2013 Open Source Robotics Foundation.
Released under the Apache 2 License.
http://gazebosim.org

Gazebo multi-robot simulator, version 1.5.0
Copyright (C) 2013 Open Source Robotics Foundation.
Released under the Apache 2 License.
http://gazebosim.org

Warning [parser.cc:361] Converting a deprecated SDF source[/opt/ros/groovy/stacks/simulator_gazebo/gazebo_worlds/worlds/empty.world].
Set SDF value
  Version[1.2] to Version[1.3]
  Please use the gzsdf tool to update your SDF files.
    $ gzsdf convert [sdf_file]
Msg Waiting for master[ INFO] [1368540701.989137839]: waitForService: Service [/gazebo/set_physics_properties] has not been advertised, waiting...

Msg Connected to gazebo master @ http://127.0.0.1:11345
Msg Publicized address: 10.17.55.151
Msg Waiting for master
Msg Connected to gazebo master @ http://127.0.0.1:11345
Msg Publicized address: 10.17.55.151
Error [Events.hh:141] Events::ConnectWorldUpdateStart is ...