2万5千分の1地形図からの国道名の自動抽出手法

抄録

An automatic extraction method of characters representing national road names in 1/25, 000 scaled maps published by Geographical Survey Institute using a computer is described. Recently many researchers are studying automatic extraction of elements of the maps, that is, characters, railroads, road networks, contour lines and so on. As character is one of the most important elements, automatic extraction of characters is needed frequently. We proposed in previously reported paper an automatic extraction method of 1.5mm×1.5mm characters which denote street numbers in 1/25, 000 scaled map. Only horizontally or vertically written characters can be extracted by this method. In the present paper, therefore, we propose an extraction method of rotated 2.0mm×2.0mm characters representing national road names written along national roads. Image data of 1/25, 000 scaled maps published by Geographical Survey Institute are input to a computer using a color image scanner, and national roads are extracted as brown figures. National road names are extracted from the neighboring regions of the national roads.