True to the ethos of 2020, the vibe of this year’s Christmas project was not a cute steam train climbing a cosy village, under a starry twilight sky. No, nobody makes Christmas-themed mayhem look as good or as funny as Terraria’s Frost Moon (okay, except maybe Die Hard). So instead of keeping the invaders in their own worlds, it was time to bring them into ours.
If the shaky video wasn’t evidence enough, this is the first time I’ve attempted video compositing – boy was it fun. I shot all the footage over November and December at various locations in Sydney’s CBD (George St, Darling Harbour, Wynyard Walk, and Circular Quay). Ideally, I was aiming for footage during twilight as the city lights show that it is nighttime (the Frost Moon is a nighttime event), but the natural light is still bright and soft. This makes the rendering easier: the shadows are soft and the lighting even, so the VFX can be melded with the live footage more convincingly. The pandemic didn’t make the logistics of coordinating visits at the right place and time easy, so Circular Quay was not well shot, unfortunately. For reference, all footage was shot with a Samsung Galaxy S10 using its main camera, which has a focal length of 26 mm when equating with a full frame 35 mm camera sensor.
I actually crammed this video out in 5 days, so the modelling and animation for all the characters was done quite hastily with low poly meshes, some PBR maps, and simple rigs. There were 15 items to model including the Naughty Present and the three variants of Zombie Elves. Not all animations were done with armatures, for example, the Copter and the tongues of the Mimic and Krampus were done with shape keys with their influence animated. The components of the Nutcracker and Santa-NK1 were kept as separate meshes and animated individually. This would’ve been the better way of animating the helicopter, but I was excited to try shape keys for the first time.
Lighting, Rendering, and Compositing
Most of the lighting was done with sunset and nighttime HDRIs with some simple area lights to match the lighting of the scenes. Camera motion tracking was done manually 6–12 frames at a time, this was before I discovered that Blender has its own camera motion tracking features built in–guess I’m saving that for the Pumpkin Moon. Some footage had reflective elements in it (the billboards in Wynyard Walk and the puddle near Tumbalong Park, Darling Harbour) so when modelling the scene geometry for the shadow catching, I also created basic materials that will catch the reflections of the characters as they walk through the scene.
When rendering these scenes, I set up the Compositor to have four separate outputs:
- The composite output, with everything combined (not used in the video);
- The direct output, which is just the characters;
- The shadow output, which just has the shadows from the shadow catcher geometry. This was used for most scenes; and
- The reflection output, this was done by crating a view layer that takes indirect light from the characters and direct light from the scene geometry. Then the outputs of the Glossy passes from this view layer were then masked by the shadow catcher output. The result is direct reflections of the characters where their shadows are, depending on the material reflectivity of the scene geometry.
When compositing the final video, I overlayed the direct pass over two copies of the reflective pass. The upper layer had its blending mode set to “Multiply” and the lower to “Hard Light” which gave the most realistic looking reflections. The opening scene with the Naughty Present was the best example of this.
The opening of the Naughty Present was a lot of fun to put together. I created a bunch of planes with Christmas themed images (and skulls) mapped as emission textures, and grouped them under a collection. When the lid opens, the particle system emits the collection of planes. Wind and turbulence fields were used to scatter the particles as they burst out.
- Opening Scene: The naughty present opens up on the light rail tracks of George St, in front of the Queen Victoria Building. This footage was taken late at night, so the colour was corrected to be brighter and bluer so it appears at twilight, to logically flow with the rest of the footage. Also used kick drum samples when the present bounced. The background noise fades out when the music kicks in.
- Wynyard Walk: Elves, Nutcrackers, and Gingerbread men invade the tunnel between Wynyard and Darling Harbour.
- Tumbalong Park: Krampus and Present Mimics join the party and stomp on a puddle near Darling Harbour.
- Darling Harbour: Yeti strolls by.
- Wynyard Walk Western Entrance: Everscream attacks the cameraman.
- Tumbalong Park: Elf Copters fly in formation over the mayhem below.
- Barangaroo: Santa-NK1s parked and driving by some taxis. Note the masking of the taxis in front of the Santa-NK1s.
- Circular Quay: Ice Queens and Flockos fly over the wharfs as the camera pans up to show the snowman head Frost Moon. Note that the moon was composited over the footage.