9. The method according to claim 8 , wherein after the transforming according to a preset view control parameter original coordinates of spatial data of an original element into view coordinates in a view window and before the rasterizing in the view window an element which the annotations avoid, the method further comprises: reducing, in the view window, the original spatial data corresponding to the view coordinates.
8. The method according to claim 7 , wherein the judging whether the plane annotation region satisfies the preset display condition comprises: generating, according to the annotation display rule, the plane annotation region at a place with the highest annotation display priority within a range where an annotation can be displayed; judging whether the bits for identifying annotation overlying forbidden are all 0s and the number of 1s of the bits for identifying avoid overlying if permitted is 0 in the pixel values of pixels within the plane annotation region at the place with the highest priority, and if the bits for identifying annotation overlying forbidden are all 0s and the number of 1s of the bits for identifying avoid overlying if permitted is 0, determining the plane annotation region is the annotation display region and ending the process; if the bits for identifying annotation overlying forbidden are all 0s and the number of 1s of the bits for identifying avoid overlying if permitted is not 0, storing the number of 1s; generating a current plane annotation region which is different from the plane annotation region in descending order of annotation display priorities; judging whether the bits for identifying annotation overlying forbidden are all 0s and the number of 1s of the bits for identifying avoid overlying if permitted is 0 in the pixel values of pixels within the current plane annotation region, and if the bits for identifying annotation overlying forbidden are all 0s and the number of 1s of the bits for identifying avoid overlying if permitted is 0, determining the current plane annotation region is the annotation display region and ending the process; if the bits for identifying annotation overlying forbidden are all 0s and the number of 1s of the bits for identifying avoid overlying if permitted is not 0, storing the number of 1s, and repeating until every region for displaying the annotation of the original element according to the display rule within the range where an annotation can be displayed has been processed; and if the plane annotation region has a stored minimum number of 1s, determining the plane annotation region with the minimum number of 1s as the annotation display region; otherwise, determining there is no annotation display region for the annotation of the original element.