how I create the pointcloud topic in moveit in order to do the octomap?

Hello everybody. i have been wondering how to really create the pointcloud topic in moveit. I did [This tutorial](http://docs.ros.org/indigo/api/moveit_tutorials/html/doc/pr2_tutorials/planning/src/doc/perception_configuration.html), but it only explains how to do once you have the topic done. I tried to create a pointcloud topic using [iai_kinect2](https://github.com/code-iai/iai_kinect2) (due to the fact that im using a kinect v2. and even if i am able to create a point cloud, if i put the topic in the yaml file, and i run a simulation, any octomap is shown. I was wondering if i have also a set any specific parameter or something in planningscene. I have been working on that a few days in I'm feeling I am doing many rounds on the same topic. Any help would be appreciated. Thank you