| 摘要 |
<p>A method for automatically displaying map symbology in a Geographic Information System. In the method, a computer (18) retrieves records (21, 22 and 23) from a data base (20) for each map feature that lies within the extent of the displayed portion (42) of the map (15). The records (22) for point features are organized in 'flat' structures (48) where each map feature is represented by a single symbol (16), and in multi-level 'hierarchical' structures (54) where each feature is represented by a hierarchy of symbols (16) representing different resolutions of the map features. For a hierarchical symbol structure, the level of records retrieved (62) by the computer is determined by the scale (44) of the map displayed to the screen (14). The computer determines (64), for each symbol (16) at the particular map scale (44), whether the symbol extensively overlaps any other symbol. The symbols that overlap significantly are modified (66) to reduce the clutter by either merging (98) the overlapping symbols into a single symbol including a numeric identifier or replacing (124) the symbol and its siblings by the single parent symbol in the hierarchy. The symbols (16) from the modified records (22) are displayed (70) to the screen (15).</p> |
