grace kelly. visual effects artists say the powerful emotion of a real life actor remain difficult to duplicate, especially one as tall lends as hoffman. digital images can benefit producers in another way. one of the visual effects artists we spoke with told us the story of a particularly petulant uncooperative actor who was finally convinced to complete his scene with the threat of a digital replacement. >> wow. did he say anchor or actor? >> he said actor. >> actor. okay. >> i was listening ing ting to saying about that. >> the old commercial was great. okay, so some new yorkers they think they have seen everything. right? >> this is awesome. >> but what about dozens of zombies hidden underground