This paper proposes vertical search stereo matching for 3-D conversion of building polygons in existing 2-D digital maps. This stereo matching is considered as a special type of vertical search locus method which uses a polygon as search window on a pair of stereo images. The 2-D coordinates of the polygon window is fixed to the known position in a 2-D map. The algorithm searches the elevation of polygon which gives the best fit between parts of stereo images within the areas where the polygon is projected. This method can be applied to 3-D conversion of building polygons in a 2-D digital map. Each searched elevation is expected to be the dominant elevation of the building roof. The experimental test shows that the precision of the vertical search is almost a height of 1 floor level and enough for city modeling or map modification on a digital stereo plotter.
