Freshman summer research project into the use of normal vectors to generate an occupancy grid based off of point cloud data.
I wouldn't recommend using this package. I developed this Freshman year of college while learning C++. While it kind of works, I never finished the implementation and it's very computationally intensive.
If you're looking for something that'll take in a point cloud and give you an occupancy grid, check out http://wiki.ros.org/costmap_2d.