The algorithm for enviroment matting is not entirely clear to me. I understand that each pixel is encoded using 3+18n parameters which accounts for everything including refraction. Then we take the images of the object before a sequence of backdrops so that we can estimate the parameters. This is where the confusion lies. How does one keep the scene static as the backdrops are changed? It is that if we are filming at 30fps then we have to change the backdrops much more than 30fps. I am a bit confused at this point