FaRmLaNd on 09 February 2010
Well the effect on the Harry Potter movies wont be as large as Avatar (which made like 70% of its gross in 3d screens), the vast majority should still be made in 2d for potter largely because the movies were shot in 2d and then converted to the 3d format which means it most likely wont be anywhere near as impressive. But it will still help.
