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Erroneous Data

The circuitry in this rangefinder reports ``floaters'' around specular items. The floating points tend to occur alone and can be removed with the following rule: a valid reading must be near at least one of its neighbors. This assumes that most of the data is valid, which it is. The floaters can be eliminated or replaced with a copy of a neighbor's position. We are also exploring estimations, since the environments scanned contain so many planar surfaces.

Another source of errors are specular objects, at the positions where the laser is reflected directly back on itself. The measurement for the highlights is closer than the surrounding area, thus the bright spots seem to hover off of the surface. While these errors have not been explored in great detail, it is our opinion that they stem from the strength of the signal returned, and can be compensated for.

Lars S. Nyland