There's a clutziness to visual effects work that I find appealing. When you think about, some common techniques are downright crude and it's amazing that they work at all. I can't believe matchmoving/tracking works so well, for example. What an ugly way to solve a visual problem. The de-aging technique in X-Men was similarly crude. The technique is called "virtual skin grafting" and involves sampling skin from one part of the actor and tracking it to another part. The amazing part to me is that someone had the idea to do this in the first place. So when I'm thinking through these effects shots I've been unafraid to try simplistic or crude approaches.
In the shot where Ben first sees the spinner he missed his mark so he's off to the side. To re-center Ben I had to fill in some missing sky. I thought that I would be able to stretch out some of the existing sky to fill up the space. But that didn't look too good. The grain looked stretched and became really noticeable. I tried blurring the stretched grain and then used AE's grain tool to put grain back in, but it still didn't look right. I tried a bunch of other things too—I reassembled the sky out of tiny sections of existing sky but that didn't look any better. Rotoscoping didn't work either. What finally worked was thinking of the sky as a giant bluescreen. Keylight didn't work at all, but somehow Color Difference Key worked great. I actually don't know how to use it, but I randomly tried some things I remember from doing blue screens a long time ago. So Ben and the bushes are basically keyed over a blue Photoshop sky with some garbage mattes to keep out some pesky bushes. One note: it would have probably been faster to just shoot a real blue sky and composite Ben on top of that. Putting film grain onto the blue Photoshop background added 20 minutes to the otherwise 10 minute render.
Photo at top: what good is pulling a key if you don't put in some weird background?
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