Hi Ugo,

I believe that that launch file has just not been edited to reflect the new distribution set up.  It loads the paths for the PR2 gazebo resources for every empty world even though it is meant to be generic. 

So, you can edit out the paths of resources that you dont have with the standard distribution.  Take out pr2_ogre, pr2_description, and pr2_gazebo_plugins. 

For example change GAZEBO_RESOURCE_PATH to:

    <env name="GAZEBO_RESOURCE_PATH" value="$(find gazebo_worlds):$(find gazebo)/gazebo/share/gazebo" />

I have a similar modified launch file setting up my own simulation. 

Regards,
Adam Stambler

On Mon, Mar 29, 2010 at 8:24 AM, Ugo Cupcic <ugo@shadowrobot.com> wrote:
Hi all,

Do I need to install pr2_gazebo to use the command:
roslaunch gazebo_worlds empty_world.launch ? Even if I won't use the PR2
robot?

I just installed gazebo_tools and gazebo_worlds but I get an error when
I try to start empty_world. (see below)

Cheers,

Ugo



Traceback (most recent call last):
  File "/home/hand/ros/ros/tools/roslaunch/src/roslaunch/__init__.py",
line 198, in main
    p.start()
  File "/home/hand/ros/ros/tools/roslaunch/src/roslaunch/parent.py",
line 217, in start
    self._start_infrastructure()
  File "/home/hand/ros/ros/tools/roslaunch/src/roslaunch/parent.py",
line 180, in _start_infrastructure
    self._load_config()
  File "/home/hand/ros/ros/tools/roslaunch/src/roslaunch/parent.py",
line 106, in _load_config
    self.config =
roslaunch.config.load_config_default(self.roslaunch_files, self.port)
  File "/home/hand/ros/ros/tools/roslaunch/src/roslaunch/config.py",
line 371, in load_config_default
    loader.load(f, config, verbose=verbose)
  File "/home/hand/ros/ros/tools/roslaunch/src/roslaunch/xmlloader.py",
line 662, in load
    self._load_launch(launch, ros_config, is_core=core,
filename=filename, verbose=verbose)
  File "/home/hand/ros/ros/tools/roslaunch/src/roslaunch/xmlloader.py",
line 637, in _load_launch
    self._recurse_load(ros_config, launch.childNodes,
self.root_context, None, is_core, verbose)
  File "/home/hand/ros/ros/tools/roslaunch/src/roslaunch/xmlloader.py",
line 590, in _recurse_load
    n = self._node_tag(tag, context.child(''), ros_config,
default_machine, verbose=verbose)
  File "/home/hand/ros/ros/tools/roslaunch/src/roslaunch/xmlloader.py",
line 359, in _node_tag
    self._env_tag(t, context, ros_config)
  File "/home/hand/ros/ros/tools/roslaunch/src/roslaunch/xmlloader.py",
line 502, in _env_tag
    self.load_env(context, ros_config, *self.reqd_attrs(tag, context,
XmlLoader.ENV_ATTRS))
  File "/home/hand/ros/ros/tools/roslaunch/src/roslaunch/xmlloader.py",
line 175, in reqd_attrs
    return [self.resolve_args(tag.attributes[a].value, context) for a
in attrs]
  File "/home/hand/ros/ros/tools/roslaunch/src/roslaunch/xmlloader.py",
line 146, in resolve_args
    return roslib.substitution_args.resolve_args(args,
context=context.resolve_dict, resolve_anon=self.resolve_anon)
  File
"/home/hand/ros/ros/core/roslib/src/roslib/substitution_args.py", line
105, in resolve_args
    resolved = resolved[0:idx-len(arg)] +
roslib.packages.get_pkg_dir(args[0]) + resolved[idx:]
  File "/home/hand/ros/ros/core/roslib/src/roslib/packages.py", line
213, in get_pkg_dir
    raise InvalidROSPkgException("Cannot locate installation of package
%s: %s. ROS_ROOT[%s] ROS_PACKAGE_PATH[%s]"%(package, rperr.strip(),
ros_root, ros_package_path))
InvalidROSPkgException: Cannot locate installation of package
pr2_gazebo_plugins: [rospack] couldn't find package
[pr2_gazebo_plugins]. ROS_ROOT[/home/hand/ros/ros]
ROS_PACKAGE_PATH[/home/hand/ros/stacks:/home/hand/Projects/Projects/ROS_can_interface/shadowhand]



--
Ugo Cupcic         |  Shadow Robot Company | ugo@shadowrobot.com
Software Engineer      251 Liverpool Road
need a Hand?           London  N1 1LX       | +44 20 7700 2487
http://www.shadowrobot.com/hand/              @shadowrobot

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