Abstract: Aimed at the problem of information imbalance caused by the amplification of the electronic map with the Euclidean distance as the amplification factor, a method of map zooming and clipping based on multi-factor Voronoi diagram has been proposed in this paper. This method can effectively avoid the problem of the map information imbalance, which is based on the Euclidean distance as the map magnification factor. The geographical elements are abstracted as points, lines, polygons and divided into two categories:point elements and non-point elements. For point elements, construct the Voronoi diagram of point elements. For the non-point elements, namely, line and polygon elements, constructing their approximate Voronoi diagram. When the user amplify the geographical elements of the target which is interested in, only need to extract the multi-factor of the target Voronoi diagram adjacent elements. And then calculate their minimum bounding rectangle (MBR). The MBR area is used in the map clipping region, and it can keep the surrounding geographical information of the users who interest in the geographical elements of the target. The method is adopted of this paper to test some regional electronic map. The result shows that The natural neighbor method based on the multi-factor Voronoi diagram can better take into account the target and its surrounding information when amplify the map. This method can improve the legibility of the map, to avoid the Euclidean distance as the map zoom factor and multiple operations.

Key words: electronic map, Voronoi, neighborhood relationship, map zooming, map clipping