| 摘要 |
PURPOSE: To execute accurately and efficiently a processing for the discrimination of navigation restrictions reflecting even the depth of water enabling execution of safe navigation in it, by providing a storage means for storing data on the navigation restrictions converted into a matrix, and others. CONSTITUTION: An electronic chart information reading program 91 reads chart data through a CD-ROM drive 70 and prepares chart data 81 of an internal format and, moreover, restricted area data 82 in a disk (HDD) 80 as a secondary storage. A display program 92 displays plotted data obtained by conducting a processing of multiplying a selected part of the chart data 81 by a prescribed multiplication factor and others, by a Mercator projection or a horizontal projection. A map setup program 93 forms corresponding area data 94 as an area matrix corresponding to a chart being displayed, out of the restricted area data, in a memory 90 as a primary storage. Since these data on navigation restrictions are stored as the matrix in the storage means herein, an access efficiency is made excellent when a row position and a column position are determined. |
