Abstract: The automatic generation of seamline network is a key problem for the mosaicking of orthoimages over large areas.To solve the problem,we presentd a novel area Voronoi diagram with overlap(AVDO).Based on the AVDO,an auto-generation approach of seamline network was given.The generated seamline network is global based and gives an effective partitioning for the regions of all orthoimages to form effective mosaic polygons,e.g.the area where pixels were contributive to mosaic for each image.The partitioning is unique,seamless and has no redundancy.By this mean in the mosaicking over large areas,we can ensure the flexibility and efficiency of mosaicking,avoid the middle results and error accumulation,and make the mosaicking results have no relation with the order of images.Experiments show that the approach is feasible.