Generate Ground truth Octomap from Gazebo World

• This repository describes a method to generate a Ground Truth Octomap .bt file from a Gazebo .world file without the use of any robotic sensors & Mapping algorithms.
• The [OpenMACE]((https://github.com/heronsystems/OpenMACE) repository is used to achieve this task & the current repository presents only the relevant parts of OpenMACE in a structured way to make the task at hand easier.

Configuration

• I tested the method on Ubuntu 18.04 + Gazebo 9.19.0 + cmake 3.10.2 in WSL2 on Visual Studio Code on a Windows machine.
• But I believe my setup should be identical to an Ubuntu 18.04 machine running the same versions of the above software.

Method

• Generating octomap from Gazebo world is acheived using a plugin built as part of this repo.
• Check-out code from the tag pertaining to your Ubuntu version.
  • Example git clone https://github.com/heronsystems/OpenMACE.git --branch=0.0.2 for Ubuntu 18.04.
  • Tag 0.0.1 corresponds to Ubuntu 16.04 & tag v0.0.3 corresponds to Ubuntu 20.04.
  • With this clone, a catkin workspace also gets created locally at <path-to-OpenMACE>/catkin_sim_environment (this'll be relevant for one of the next steps).
• Build the repo using the instructions here
  • Look at this for a note on the errors you might encounter in this step.
• Install tf2-sensor-msgs
  • For melodic, sudo apt-get install ros-melodic-tf2-sensor-msgs works.
• Install octomap-ros
  • For melodic, sudo apt-get install ros-melodic-octomap-ros works.
• Go to OpenMACE/catkin_sim_environment local folder & build the catkin environment.
  • cd <path-to-OpenMACE>/catkin_sim_environment && catkin_make
  • The plugin should be located at <path-to-OpenMACE>/catkin_sim_environment/devel/lib/libBuildOctomapPlugin.so
• Add the plugin into your desired gazebo .world file as shown here.
• Run Gazebo with this modified .world file & call the octomap service as shown here
  • While executing the rosrun command, set the GAZEBO_PLUGIN_PATH env variable to the directory containing the libBuildOctomapPlugin.so plugin so that Gazebo can find it.
  • While executing the rosservice command, source the <path-to-catkin_sim_environment>/devel/setup.bash file in the terminal in which you want to run rosservice command.

Note

• From my experimentation, I found that the coordinate frame for the resulting octomap is the same as the Gazebo coordinate frame.
• i.e, The coordinates of a voxel of interest in the resulting ocotmap will be the same as the coordinates of the same voxel in Gazebo.

Errors

• Facing a few errors (and not resolving them) was alright for me as long as the libBuildOctomapPlugin.so plugin got built after running this catkin_make command.
  • While building the repo in this step, I came across the below warnings & errors but (at least) these didn't effect the plugin build.
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Additional Links

Here are a few more additional useful links

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