A Shadow Detection Algorithm Based on Phong Lighting and Radiosity Model
Cai Xuan-ping · Modern Electronics Technique · 2008
Focusing on the problem that shadows cast by moving objects are detected incorrectly as foreground targets by most of the current moving objects detection algorithm,a method of shadow detection based on the Phong lighting and radiosity model is proposed.Based on the Phong model,we analyze the brightness of pixels in image sequences,the Relative Change of Brightness(RCB) in shadowed regions is proved to be more stable than moving objects regions,it is measured by the covariance of RCB of pixels on a template(5*5) so as to acquire the first discriminant.As the RCB in shadowed regions is stable in image sequences,a filter template is designed to make the RCB more unstable in regions of moving objects,so the second discriminant is presented.Shadow detection is carried out by fusing the two discriminant formulas described above,experimental results are evaluated quantitatively and qualitatively,and show that our method is robust and offers more advantage over other algorithms presented previously on detection rate and discrimination rate.