Building and navigating maps of road scenes using an active sensor

The author presents algorithms for building maps of road scenes using an active range and reflectance sensor and for using the maps to traverse a portion of the world already explored. He describes some advantages of an active sensor, namely, that it is independent of the illumination conditions, does not require complex calibration in order to transform observed features to the vehicle´s reflectance frame, and provides 3-D terrain models as well as road models. Using this map built from sensor data facilitates navigation in two respects: the vehicle may navigate faster, since less perception processing is necessary, and the vehicle may follow a more accurate path, since the navigation system does not rely entirely on inaccurate visual data. The author presents a complete system that includes road-following, map-building, and map-based navigation using the ERIM laser rangefinder. Experimental results are presented