Grid-referenced data bases have been demonstrated to provide the geometric realism and geographic accuracy needed in navigation-related simulation trainers. When terrain data are represented directly in the spatial domain through curve fitting and direct data compression techniques, such as plane extraction and line segment representation, the ability to provide information with variable resolution without sacrificing the geographic integrity of the data becomes extremely clumsy.

A method is discussed in this paper where data is transformed through a linear mapping into a representation space consisting of continuous functions that possess the sequency property. When referenced to a grid, it is found that the resolution of the reproduction is tied into the sequency of the vectors themselves, thereby providing a means for representing the terrain data with variable resolution. This also provides an easy means for providing a nested variable resolution reference grid. Finally, the reproduction resolution can be further varied in the reproduction process itself by using only the lower sequency coefficients available in a record.

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Robert Wang