Abstract: Object shadow computation is a critical issue for object rendering in image processing,and thus it is an important research issue in image processing field.In order to further improve the efficiency of shadow rendering,this paper proposed a clustering based object shadow recognition algorithm.We represented each light as a sphere according to its attenuation range,classified lights into different classes while the distance between them extended the predefined minimum distance,and applied a top-down hierarchal clustering method for lights.During the process of clustering,the attenuation range of light increases linearly with the distance between light and the light source.After clustering the lights into different classes,we rendered lights of a class by the same texture,and thus,the efficiency of rendering shadow in an image is improved largely.Finally,we validated the efficiency of our algorithm according to some experiments.

Key words: Object rendering,Shadow computation,Clustering,Image processing