ABSTRACT
As spatial features become small relative to the bounding box, ¢xed-form features (called vector data in geographic information system [GIS] jargon) become less ef¢cient as a means of representing spatial structure. Area declines as the square of spatial span while perimeter declines linearly, giving rise to larger perimeter-to-area ratios and requiring relatively heavier investment in computer storage capacity for explicit coordinates. Likewise, the number of rows in an attribute table becomes so large that direct user access is discouraged. Therefore, a second general mode of managing spatial data becomes more attractive and tractable. It is also conducive to map modeling for synthesizing sophisticated indicators pertaining to complex concepts. This second mode entails raster referencing for spatial speci¢cation, with raster being a row-column pattern of positions.
