Creating custom Gazebo world files from sdf's/dae's for use with roslaunch

edit

For anyone having a similar problem and coming across this after 6 years, you can make gazebo look in the package directory for models using the package.xml. In the below example, you can put your models into <your/package/directory>/models/ and use them from the world file without copying them into the default gazebo model directory (This might not have been available in 2014 when the question was asked)

<export>
    <gazebo_ros gazebo_model_path="${prefix}/models"/>
    <gazebo_ros gazebo_media_path="${prefix}/models"/>
</export>

Here {prefix} is evaluated to the package path

In the world file, now you can do this

<geometry>
    <mesh><uri>model://your_mesh.dae</uri></mesh>
</geometry>

We struggled for 1 week with this, here is our solution to contribute back to the community:

if your run rosrun gazebo_ros spawn_model -h you notice there is a flag called:

-package_to_model - optional: convert urdf <mesh filename="package://..." to <mesh filename="model://..."

This allows you to transform during runtime your urdf file so that your meshes are loaded from gazebo model folder located under /home/user/.gazebo/models , all that is left is to add some installs in your my_robot_description pkg.

Edit your my_robot_description -> CMakeLists.txt file, e.g.

roscd my_robot_description && gedit CMakeLists.txt

Add the following lines at the bottom:

# the place where gazebo puts the models by default
set(GAZEBO_MODEL_PATH $ENV{HOME}/.gazebo/models)

# to create folder : /home/user/.gazebo/models/my_robot_description
add_custom_target(COMMAND cmake -E make_directory ${GAZEBO_MODEL_PATH}/${PROJECT_NAME})

# copy my_robot meshes to gazebo models folder
install(DIRECTORY meshes
  DESTINATION ${GAZEBO_MODEL_PATH}/${PROJECT_NAME}
  FILES_MATCHING PATTERN "*.dae"
  PATTERN "*.png"
)

make sure to compile your my_robot_description pkg with the right flag:

catkin build --this --make-args install

And finally of course, spawn your model in gazebo with the above mentioned flag, e.g.

<!-- spawn your robot (in a certain position) -->
    <node pkg="gazebo_ros" type="spawn_model" name="mbot_spawner"
          args="-package_to_model -urdf -model mbot -param robot_description -x 0.5 -y 0.5 -z 0.01" />