Where are gazebo .world files?

Question

I installed ros melodic desktop full version. Os used Ubuntu Bionic. Gazebo that got installed along with ros is 9.13.0. Now I am trying to follow http://wiki.ros.org/simulator_gazebo/Tutorials/StartingGazebo . When I execute roslaunch gazebo_ros empty_world.launch , gazebo is launched but no world view(the one with sky is there) . Observations:

1. Upon examining the gazebo_ros pack I do not find any .world files.

2. the empty_world.launch refers to

   <arg name="world_name" default="worlds/empty.world"/> <!-- Note: the world_name is with respect to GAZEBO_RESOURCE_PATH environmental variable -->
   

but there is no .world file in the entire package.

3. Also the command env | grep GAZEBO_RESOURCE_PATH does not yield anything. The gazebo tutorial http://gazebosim.org/tutorials?tut=ros_roslaunch&cat=connect_ros says that .world files would be present at /worlds directory of Gazebo resource path but there is no gazebo resouce path.

Thank you.

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Originally posted by sarojj7 on ROS Answers with karma: 13 on 2020-04-11

Post score: 1

Answer 1

Upon examining the gazebo_ros pack I do not find any .world files

Gazebo 9 is not a ROS package, but a system dependency (ie: independent of ROS).

gazebo_ros is not the package which "provides" or "contains" Gazebo, but (from here):

Provides ROS plugins that offer message and service publishers for interfacing with Gazebo through ROS.

So its directory not containing those .world files is expected and normal. It only provides some plugins which are used with Gazebo and ROS, not Gazebo itself.

Many .world files are distribute as part of the gazebo9-common debian package. You can find them in /usr/share/gazebo-9/worlds, including empty.world.

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Originally posted by gvdhoorn with karma: 86574 on 2020-04-11

This answer was ACCEPTED on the original site

Post score: 0

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Original comments

Comment by sarojj7 on 2020-04-11:
Thanks for the prompt response. Upon sourcing the path /usr/share/gazebo-9/worlds to .bashrc file, the issue solved. Now .launch finds the models in the mentioned path and loads .world file accordingly. Just for the benefit of others, the names of .world files in the .launch files in the gazebo_ros package is not same as the files present in /usr/share/gazebo-9/worlds, like elevator_world.world is elevator.world there.