Neat Method for Keying in Nuke!
So this is a method of pulling keys in After Effects that I tried to emulate and adapt for Nuke. I wasn’t sure how it would turn out, but it actually worked really really well! So I thought for my behind-the-scenes blog I would make a post about it.
I did not come up with this method, I only adapted it for Nuke. All credit goes to James Whiffin from Digital Tutors, that's where I learned it from. Lets get started! (Also warning for hella long post)
So this is my plate, featuring the wonderful collasasaurusrex as my sci-fi adventurer. The armour pieces are from a master chief suit that I made.
So the general theory behind this keying method is to isolate the plate and use Keylight to sample just the smallest amount of green that we can to make the key more accurate. Essentially we are using Keylight to generate a very precise garbage matte. We will walk through the steps, starting with DENOISING the plate. Always step one.
I think isolated noise patterns are just the absolute coolest looking things ever.
Then after a really quick garbage matte we will pull a super rough key using Keylight. Primatte will also work for this, as we are just trying to get a very solid core matte, the edges don’t really matter.
After you get a solid core matte, you want to erode out the edges of your alpha channel until they are showing just a few pixels of green. The Erode should work for this, or you can just use the mask expansion that is built into Keylight. That’s what I did.
Voila! Now we have a super precise garbage matte that draws perfectly and tracks our subject through the shot. Now when we sample the green with a second Keylight node, we are only analyzing the section of the green that matters without bogging down the calculations with frivolous values.
So that is the method. It uses two keylight instances and helps to make the Keyer more accurate in its calculations. Here is the node structure I had:
And here is a very rough temp version of the final comp. Just to show it with a background. I also removed the right arm because I am replacing it with a cool robot one!
So that’s all folks! Thanks for reading and sorry for cluttering your front page with a long post. If you have any questions or comments or this is a terrible method and you can’t believe I am doing this instead of a different way then let me know!