The function to acquire three-dimensional information of the environment is crucial for the robots, especially mobile ones, and a range-finder which directly measures the range information with an active scan of a laser beam will be extensively used in the future. Based on the outlook that such range-finders will be manufactured in the near future, this research discusses some of the basic problems of the signal processing of the range-finder, especially when it is used to reproduce a terrain map for mobile robots. The following results were obtained: (1) The reflecting points of the laser beam on the ground surface are radially distributed and, therefore, a specialized method (Radial B-spline Interpolation) can be introduced for interpolating the beam points. By separating and applying special processing methods to shadow regions, better results of the interpolation can be produced. (2) An interpolation method in association with the memorized information is shown to be feasible for signal processing of terrain. The method of memorizing terrain, and the associative application of the memory to new terrain is proven appropriate based on a computer simulation, and further improvement of the estimation is demonstrated.
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