Procedure to construct map images using vector data is explained. The DLG-format data stored in the CD-ROM of the Geological Map of Japan 1 : 1000000, 3rd edition (GSJ, 1995) is used as an example of the vector data. To construct the digital geological map images, line data for all geological unit is firstly extracted from the DLG data. Applying the rasterization technique to the line data, the map image is drawn as a description in the PostScript language or a TIFF image data file. For the above process, the software executable on the UNIX operating system is introduced.

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Drawing method of the density diagram by Mellis method in the stereographic projection on a personal computer is proposed with a sample program in BASIC. In Mellis method, the density is shown by overlapping of 1% small circles drawn round all plotted points. In the proposed method, the small circle is painted through stippling of all dots within the small circle on a computer graphic screen. When the circle partly or fully overlaps another circles, those overlapping areas are changed to another colors. As colors are set for overlapping numbers from 1 up to 14, each color area in the drawn diagram just shows the density. Then, these color areas are arranged and changed into 5 different color areas to each other, and these 5 color areas replaced into different non-colored patterns to each other, which can be printed with monochromatic type printer through operation of hard copy of the computer screen.

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Kouda and Suwijanto (1991) reported that pattern recognition of satellite images like a cauldron was one of effective means for mineral exploration on the area such an isolated island in the tropical region with less information of metallic deposit.
It is difficult to develop a program recognizing a polygon in an image from combinations of many linear pattern of skeletons.
In this paper, the method of matching coordinates values of skeletons with a regular hexagon by using a mapping function between a polygon and a unit circle on a complex plane is proposed. As coefficients of the mapping function in a polynomial form of a complex variable are given by Yamazaki and Gotoh (1971) for a normalized hexagon, both scale and inclination of a regular hexagon can be estimated by coordinate values of skeletons on an image. A correlation ratio of an estimated regular hexagon to skeletons specified on an image is used as a matching index of a pattern composed of skeletons.
As applications of the method, matching indices are shown in two cases of the Lomblen island, Indonesia, and the Shikotsu-Tohya region of Hokkaido, Japan. It is shown that the method is applicable to estimate a regular hexagon from skeletons which are not located over the lineament of the hexagon.

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