A high speed geocoding method for location-based service with coloring map images

This paper proposes a high-speed reverse geocoding method for location-based service. In geocoding, the longitude and latitude become mutually convertible with the ldquoarea name.rdquo The ldquoarea namerdquo is an address and landmark name such as ldquoKoganei Cityrdquo and ldquoTokyo Towerrdquo that are easy for the user to understand. In traditional reverse geocoding methods, long conversion time and low conversion accuracy are problems. Our method reduces these problems by using image-based conversion methods. First, we create ldquocolored map imagesrdquo and a ldquocolor mapping tablerdquo for a region from the vector data used in the GIS. Second, we convert the longitude and latitude into a color code such as ldquoFF00EErdquo using the colored map images. Finally, we obtain the area name from the ldquocolor-mapping table.rdquo By this method, we can get the area name from the longitude and latitude without a long calculation time that depends on the number of reiterated areas. We evaluated the proposed method using the data of a segmented ward, city, town and village of Saitama Prefecture in Japan. As a result, we increased the conversion speed by about 70 times. In addition, we reduced the conversion error rate in comparison with the traditional point-based conversion.