SEGMENT DIVIDING METHOD FOR DIGITAL MAP DATA

摘要

PURPOSE:To shorten the time for reading digital map data out of a segment buffer and displaying the data on a graphic display device by dividing and storing segments in a region across a part of the segment regions enclosing the crossing intersected points of a checkerboard grid. CONSTITUTION:The digital map data are divided like the checkerboard grid to the segments 2A to 2I and are stored into the segment buffer of the graphic display. The data are also divided to the segments 2J to 2M and are stored in the region across a part of the region of the segments 2A to 2I enclosing the crossing intersected points 6 of the checkerboard grid. The digital map data are, therefore, read out of the segment buffer at the time of displaying a desired region on the graphic display device. The segmenting of the display region from the segments 2J to 2M in the region across a part of the region of the segments 2A to 2I enclosing the intersected points 6 is possible in the case of displaying of the region including the crossing intersected points 6 of the checker board grid. The segments which can be displayed with a small number of the segments are thus selected and displayed according to the position of the region desired to be displayed. The time to the display of the screen is shortened in this way.