Automatic Placement of GIS Vector Map Annotation in Area Feature by Long-Diagonal

This paper discusses the placement of Chinese annotation from point of view of graphics. Area Feature is classified as simple polygon, complex polygon and special polygon. For simple ones, annotations are placed along the longest edge. For complex ones, firstly the polygons are simplified according to close points, then the longest diagonal is gotten, lastly, annotations are placed along long-diagonal. For special ones ,the polygon is partitioned off several parts by a certain rule for getting its sub-diagonals, then its annotation is placed by means of the second.