Hello all! Today I’m going to break down one of the simpler Visual Effects (VFX) shots from Project London. Take a look at the finished shot first.
Creating this shot started when I was looking through some of the aerial footage we shot last year. We were up in the air for a few hours, shooting the whole time, so I knew it was likely there was some great footage in there that we either never had a use for or had just forgotten about. And I wanted to be really familiar with the footage when I started working on the finale so I’d have an accurate mental inventory.
I found one shot that was particularly nice; the sun setting over Seattle, looking out over the south end of Lake Washington, with downtown Seattle far off in the distance jutting up in the haze like a part of the landscape. Barry Gregg held the frame on the sun a long time, and it was a particularly steady shot—it seemed a pity we hadn’t done anything with it. So, just for kicks, I decided to use it.
So there’s the raw plate (above). I thought it might make a good transitional shot (since transitional shots don’t always necessarily need to tie directly into a scene, but can just express the passage of time), and so I figured I might as well put the protagonists ship in there to show them flying somewhere.
First thing I had to do was motion track the shot so that the added elements would match the live-action camera move—this was easy. I just used a point on a skyscraper as a location track point, and some random tree over on the left to extract the rotation. Once I had tracked the motion, I applied it to an empty (empty = After Effects lingo). Now, anything I parented to that empty would copy the motion of the shot.
I wanted an animation of the Goose (the ship created by Dolf) flying towards the sun, but didn’t really want to render anything new out from Blender (this was just a ‘for fun’ shot, after all, and I didn’t want to spend too much time on it). I skimmed through thousands of frames I’d rendered out of the Goose. Each animation is rendered out as a PNG sequence, complete with alpha channel, so there were plenty to choose from.
I finally stumbled upon one that looked promising:
Okay, so it was aimed at the camera, but that’s easily solved! If it’s a silhouette, nobody can tell which direction it’s going anyway.
I tweaked the max white levels so that only a little bit of the detail was still visible, shrunk the ship down, and plunked it into the scene. It worked! (See below.)
I found a picture of clouds and put it in the scene too. I liked it, since it kinda divided the shot into three bars, dark clouds on top, bright sky in the middle, and dark ground below, with all the relevant subjects of the shot being dark images in front of the sky—a fun composition, and made a more interesting use of positive and negative space.
However! This film is sci-fi, in an alternate reality, and has some pretty weird buildings bejeweling the Seattle skyline!
First off is a massive tower (above), a common sight in the film. I had some pre-existing renders of it lying around, so I snagged one. The perspective didn’t match perfectly… but I thought it might still work.
I dropped in the buildings. I was able to blend one in well enough, but the gradient of the sky and the haze made compositing the second one a bit difficult—particularly because while the one on the right is on top of the hill, the one on the left is behind a closer hill, and needs to pass behind it. Since the ground grows lighter the further into the distance it gets, I figured I could just create a key using the brightness of the pixels.
Here’s a representation of the matte I created (above). Notice how everything beyond a certain brightness in the plate has been turned green (the green is just for visibility’s sake)! The best part about this method is that it doesn’t cut straight to green—it fades into it, which means that especially low down on the horizon we’ll still have a bit of atmospheric difference overlaying the building, which is awesome!
So here’s the composition after I laid that new keyed foreground layer back over the building—looks pretty darn good (above)! I parented both buildings to the empty so that they would match the movement of the shot. However! This shot takes place after a pretty big battle, and I wanted some smoke still drifting in the air. I found a picture of clouds, tweaked the levels, set them to multiply, blurred the edges, and laid them over the shot. Voila! It looks like a light layer of smoke is drifting away from the city. I also added some subtle reflections in the lake, tweaked the brightness, and…
…There we go! The finished shot (above and below)! Just a background plate with a few other stills tracked in—piece of cake! Sure, it may not hold up 100% if you study it forever, but as long as nothing would jump out and draw you out of the movie, I’ve done my job!
One of my favorite things about this shot is that the CG doesn’t take the center stage; everything is more-or-less background. There are a lot of shots like this in the movie, and I think that really grounds it.
Well, that’s about it! I hope you found it entertaining/informative!