All you have to do is to launch the octomap server, properly remapping the pointcloud topic, and set your global frame to whatever you are using, odom_combined should be OK. An example is given here:
https://github.com/OctoMap/octomap_ma...
Your remap pointocloud topic would be most probably: <remap from="cloud_in" to="/camera/depth/points"/>
Additionally, you have to launch rviz: rosrun rviz rivz
, add a new display of type MarkerArray and subscribe to the topic occupied_cells_vis_array
.
Obviously, you have to launch also the openni2 camera: roslaunch openni2_launch openni2.launch
(note you have to install openni2_camera and openni2_launch packages for this).
To put all that together in one launch file is straighforward and thus I let that to you :)