@InProceedings{heipke-etal:95,
  author =       "Christian Heipke and Carsten Steger and Ralph
                  Multhammer",
  title =        "A Hierarchical Approach to Automatic Road Extraction
                  from Aerial Imagery",
  editor =       "David M. {McKeown Jr.} and Ian J. Dowman",
  series =       "Proc. SPIE 2486",
  pages =        "222--231",
  booktitle =    "Integrating Photogrammetric Techniques with Scene
                  Analysis and Machine Vision {II}",
  year =         "1995"
}