The art of ‘Togo’s’ procedural icebergs, and other snowy scenes

Exploring DNEG’s digital environments in part 3 of our ‘Togo’ series.

Parts 1 and 2 of befores & afters’ special coverage of Togo looked at DNEG’s CG dog work for the film TOGO.

Another significant aspect of Togo involved digital environments, either as completely synthetic landscapes or augmentation of live-action photography captured in Alberta, Canada, standing in for Alaska.

Two of the principal sequences requiring digital environments included one set on Little Mount McKinley (filmed at Fortress Mountain in Alberta). And another along the frozen Norton Sound (photographed on Alberta’s Abraham Lake). The latter location becomes a dangerous journey as the ice breaks up, ultimately requiring procedurally generated icebergs.

Production visual effects and DNEG VFX supervisor Raymond Chen and DNEG digital effects supervisor Russell Bowen return to concentrate discussion here on the Norton Sound work. Where live-action plates featuring sledding dogs were modified and enhanced. Chen and Bowen also look into the other snowy and mountainous environments built for the TOGO film.

Original photography.
The final shot of Togo.

Crossing a frozen lake in Alaska, but filming in Alberta, and relying on roto (a lot)

Raymond Chen (production VFX supervisor): The crossing scene was filmed at Abraham Lake in Alberta. The reason that location was picked was that it has very clear blue ice. It’s a very windy area. So, it doesn’t get covered with snow. Unfortunately, the weather didn’t co-operate when we shot there. Moreover, we only had one or two days of clear ice before it got covered with snow. Luckily we took a lot of photos.

Russell Bowen (DFX supervisor, DNEG): They really did go out and film with the sled and the dogs. That meant roto became a big part of the sequence. 95% of the scenes were the dog team and Willem Dafoe, and everything else around them changed. So, the whole dog team, all the ropes, all the sled, the fur, the jacket, Willem’s hair. So, everything needed to be pulled out of the plates.

Plate.
Final.

Chen: It wasn’t just roto that was needed to separate them off the plate. We also had to actually build in layers because you need the dogs further back to be in more atmosphere than the dogs in front.

Bowen: Yes, usually you’re projecting the roto layer onto a body track or an object track of the character or the vehicle and then you can layer something in. But in this case, because we had all the intricate details of the fur, we actually had to use the roto projected onto cards, and then build the sled system as a card rig for the comp artists to then layer in all of the particle FX and snow and atmosphere. Most of that atmosphere – snow and ice and everything kick up by the sled and dogs – was Houdini simulations. It was also topped up with 2D elements.

Plate.
Final.

As the ice breaks

Chen: When the sea ice begins breaking up, it became a very complex sequence to choreograph. The plates that we were working with were of them on flat ice, which we needed to make look active. The shots where they basically get flipped up onto ice were essentially fully CG shots. We employed a number of tricks in the ones that weren’t CG by breaking the track from the camera.

Bowen: We were limited in terms of what you could do without breaking the parallax, but you could certainly do some 2D tricks of constraining them to a moving piece of ice, keeping the camera locked, or vice versa, start moving the camera and keeping them on the plate…

ice breaks
Plate.
ice breaks
Final.

Chen: …and then adding in 2D drift to that to make it all look unsettled. It was difficult because the plates themselves were on flat solid ice with different lighting conditions, as we shot over a couple of days and weeks. The conditions changed by the hour or by the minute, so each plate was different. Trying to make that all consistent while also then trying to get the choreography of art directing icebergs underneath them and how they break up and jumping from one to the next – that was a lengthy process.

Simulating icebergs, explained

Bowen: Our approach to the icebergs needed to be as procedural as possible because we needed to be able to art direct the shape of the icebergs. It was important to show them crossing the sea and jumping from berg to berg, which meant we couldn’t just have them as flat pieces of ice; we actually needed to have animatable icebergs.

Plate.
Final.

But, when you have a couple of thousand of them, you can’t rig every single one. You can’t go through the entire build process of sculpting and texturing and lookdev’ing individual icebergs, because then you’re locked to a size and a shape. And if they wanted to change an iceberg, you were then going back to build and rebuilding it. So what we came up with was a system where Layout and Environment would build the layout of the icebergs almost on a shot-by-shot basis.

Layout were laying out a very basic kind of proxy shape in Maya. We built some tools where they would be able to draw the shape of an iceberg using Maya’s curve tools and then do an extrusion, place them out in the scene, snap rig constraints to it, animate a rough animation constrained to a moving ocean in what we called our Cascade system, which was breaking up the ice.

Plate.
Final.
That then got exported out of Maya into Houdini.

Our Environment team built a really impressive toolset that would take those very basic geometry sets and procedurally model icebergs, everything from the broken edge detail to all the interior bubbles and fractures and faults inside the ice. It was doing all of that procedurally on the fly. By the end of the show we could turn around a shot in a day, and it would be on the farm that night.

If at any point the size or shape of an iceberg needed to change, we would just go to Layout, redraw the curve, pass it back down through the pipe and everything would just go through. At Effects, they would also run simulations on the bergs to deal with water interaction where there was slush and bubbles and foam. We then do our final rendering in Clarisse.

Final shot.

Other mountainous moments

Chen: We managed to shoot a lot of beautiful footage of the mountains. However, then a lot of it was modified. For example, we went up to Fortress Mountain in Alberta for the Little Mount McKinley sequence in Snow Cats. It was beautiful photography, but the director said, ‘There are trees everywhere. There’s not supposed to be trees.’ And that meant we had to change a lot of it.

There were also Alaskan mountains needed for shots in the scenes set in the houses of the settler’s compounds. There were shot with barely a mountain in the plate.

mountainous moments
Plate.
mountainous moments
Final.

Bowen: We weren’t going to build a hundred matte paintings, that would have been too much work. So we ended up going with a 3D approach, informed with a combination of digital elevation models, Lidar scans and photogrammetry.

Our environment lead Bruno Leveque came in and did a lot of sculpting. The mountains that were in close proximity were all sculpted, textured, lookdev’d, with a lot of Clarisse work for tree layouts and foliage and rocks. There really was a lot of work behind all the different landscapes.

Don’t forget to re-visit parts 1 and 2 of our Togo coverage where DNEG’s team outline the build and animation process behind their digital dogs.

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