The CityFlyer project at the CCNY Robotics and Intelligent Systems Lab is using Ascending Technologies Pelican and Hummingbird Quadrotor helicopters to do research in 3D mapping and navigation. The Ascending Technologies platform provides a 1.6Ghz Intel Atom processor, 500 gram payload, GPS, and barometric altimeter. The CityFlyer add several sensors, including a Hokuyo URG-04LX and IMU. The Hokuyo URG has been modified to double as a laser height estimator. The CityFlyer project is able to combine data from these sensors to do indoor SLAM using GMapping.
http://www.ros.org/wiki/laser_height_estimation The package provides a height estimate using a Hokuyo laser scanner. http://www.robotshop.com/hokuyo-urg-04lx-laser-rangefinder-2.html http://robotics.ccny.cuny.edu/blog/node/20