Saturday, March 17, 2012

Sky Replacement

As I casually celebrate Saint Patrick's day with some friends in Burlington Vermont I still wish that I was somewhere warm and sunny. But soon I will be back under the grey skies of Ithaca. There is a way to get yourself under a bright blue sky anytime you want through video, sky replacement. Generally the sky is just white or grey, this is easy to key out and replace with whatever sky you choose and because clouds usually don't move very fast a still image can be used and motion tracked. Andrew Kramer explains it all very well on this tutorial. I wonder just how often this technique is used professionally.


  1. Sky replacement is probably one of the most used effects in movies and videos of every kind and like you mentioned one of the easiest since the high contrast between sky and ground can be used to pull a good key for matting-in the new sky. Care must be taken though to use a sky that can "belong" in the scene, otherwise our very smart brains will detect the fakery... In fact compositing, which usually involves a good deal of replacements is the subject of our upcoming classes, and is, without any doubt the most widespread application of After Effects .