Keying in Blender
- Software:Blender 2.72 ·
Making animations special!
The special effects industry is booming! But it takes a lot of people a lot of time to make a movie. Even short films, like the Blender Foundation’s open movies, take a lot of effort and resources. What if your project is even smaller? What if you just want to treat a shot in your small video differently or perhaps chroma-key out some background to add a new element into the shot? Is there a quick way to do an effect that isn’t available in Blender’s Video Sequence Editor or VSE? Why can’t we simply send our edited strips to the compositor and trick them up there? To answer these questions we have to understand Blender’s production flow, or the hierarchy of tools.
At the top sits modelling, sculpting, lighting and animation tools. When you are done creating objects you need to color them in. So logically following that is material editing and texturing, here we find all the painting tools. Once you have animated a shot you now have a ‘source scene’. You can render it out as single images, or passes to be combined in the Compositor tool. Here you can treat the image any way you want and add other images together. Finally you string out the treated ‘source scenes’ from the compositor, in the VSE so that they play back one after the other. You can see from this ‘order of tool operation’, that there is no way for media to flow back up hill as it were, from the VSE to the Compositor. Neither can you send media that you create in the compositor back into the 3D view. No, Blender just expects that you will render all that stuff out first. Not terribly flexible, but very reasonable and sensible to code for.
“Great” I hear you say, “…so how am I supposed to get my shots back into the Compositor?” The trick is… you don’t. At least it’s not the original strip that you send back up, you import a copy to the compositor and use that back in the VSE. Let’s look at that now. Bear in mind that this workflow only allows you to send one piece of video back to the compositor at a time.