The Clipping Of Raster Image And Vector Image

With the development of computer technology, computer graphics technology develops swift and violently. The clipping of graphics is the most basic contents in CG. it is a useful tool in algorithms about hiding line, hiding face and showing of third dimension graphic. In the past, clipping algorithm centralized in clipping line and polygon. During practical research, comparing with line clipping, polygon clipping has high rate of utilization, so it is the main subjects of clipping studied at present.This paper puts forward an efficient algorithm for polygon clipping, and it is suitable for not only concave polygon but also the polygon with hole in it. This algorithm can be applicable to not only the "intersection" of polygons, but also the "union" and "subtract" of polygons. In addition, it suits for the case in which polygon clipping turns out a lot of discrete consequential polygons, so this algorithm is general to all kinds of polygon. The whole algorithm adopts single chain table as input/output data structure and there is no need to specify the direction of polygons input. At the same time, this paper proposes some new technology and method as the foundations of this algorithm. At the end of this paper, the author compares this new algorithm with other similar algorithm and the compared result indicates that the new algorithm is superior to similar algorithm in store space, speed and calculation.Moreover, based on in-depth research of" the existing scan-line polygon fill algorithm, the author has introduced a new fast method for clipping arbitrary boundary areas algorithm which uses the edge consistency and the scan-line consistency and adopts sorted chain table, i t can reduce the quantity of calculating intersection points and improve the efficiency of algorithm. Consequently, we can clip the arbitrary shape areas surrounded by line and curve.