@InProceedings{Achtelik09SPIE,
  author = 	 {M. Achtelik and A. Bachrach and R. He and S. Prentice and
                  N. Roy},
  title = 	 {Stereo Vision and Laser Odometry for Autonomous
                  Helicopters in GPS-denied Indoor Environments},
  booktitle =	 {Proceedings of the SPIE Unmanned Systems Technology XI},
  year =	 {2009},
  volume =	 {7332},
  address =	 {Orlando, F},
}