Speed compositing: 64 shots in 4 days

Having finished rendering and vfx shots, and with a little more than a week to deadline, compositing was next on the list. Beforehand, I had estimated compositing would take a day or two. I had already test comped nearly one third of the shots and thought I could use those as templates for the rest. The only thing I hadn’t done before in any shot was thinking about the suns position and the movement of the clouds.

When applying math however, it turned out I would have on average 11 minutes to complete a shot, rendering time included, if I were to do all shots in one day and have time to eat and sleep too. Considering I would have to do some rotoscoping on most shots, and the longer shots could take up to 12 minutes to render, I set my aim to finishing in four days in stead. This would give me approximately 45 minutes per shot.

The process went fine, though it was rather tedious and repetitive. While working on the first few shots, I realized the ground had a quite homogenous yellow colour that looked pretty boring. Seeking to resolve this, I thought I’d introduce cloud shadows on the ground to break things up a bit. Shadows moving across the landscape would also slightly liven up the background. I had seen Gareth Edwards do this on Attila the Hun and thought it had a nice effect. Unlike Edwards however, I didn’t have the render passes and with no time left for going back into 3ds max, I decided to fake some. My approach was to use the noise map in Nuke combined with a corner pin to make the far away shadows appear smaller than those closer to the camera. This worked well as long as everything stayed nice and flat, but the effect was ruined if something that wasn’t flat and level with the ground entered the frame. Such as a prop or a character. As a fix, I had paint out the noise map where it happened to intersect with a character or prop. I thought nothing of it for the first 10 shots or so, but then realized there were 54 more shots to rotoscope in the same way. Luckily, I soon discovered a better way that worked most of the time while watching Greg Astles talk about Nuke on fxguidetv #059. By using the ZBlur (Depth Of Field) tool in an unconventional way and leaving the Focus Plane feature on, I could zoom in on a particular “slice” of the z-depth map I had already rendered and get a decent matte from it. I later found the ZSlice tool which I guess does the same thing, only simpler to use.

I ended up compositing the film in four days, though I had one day off in between, and am reasonably happy with most of the shots. Some shots have a look that is a little too different from the rest, but I really didn’t have that much time to stop and reflect when compositing 16 shots a day.