Abstract: A parallel computer synthesizes a digital map. The computer includes a first stage and a second stage. The first stage includes a background processor for generating a map background image and N overlay processors for generating first through Nth map overlay images of non-relocatable map features. First and second sets of interim buffers are alternately connected to the background processor and to the N overlay processors. The second stage includes a second stage processor connected to the output of the first and second sets of interim buffers for combining, according to a predetermined priority, the overlay images generated by the processors of the first stage to generate a composite map image. The second stage processor also generates a final map overlay image of relocatable features, and combines the composite map image with the overlay image of relocatable features to generate a display map image.

Abstract: Digital maps digitized by scanning paper maps are smoothed by identifying regions which should be of a uniform color, empirically selecting sets of colors which the pixels of a given region might have in the raw map, empirically determining the statistical probability of occurrence of pixels of each color of the selected set in the region, defining groups of connected pixels having colors within the selected set, and resetting the color of all the pixels in a group to a predetermined region color if, and only if, the pixels of the group satisfy the determined statistical probability of occurrence. The inventive method provides uniform coloring of the map where desired, without affecting the sharpness of small-print map annotations.