The digital environment in the film
What we mentioned above are all about the production of CG sled dogs. There are many natural environments in the film, some of which are fully synthesized digital landscapes, and some are enhanced effects after real shots in Alberta, Canada. The two main scenes are Wheat Kinley Mountain shooting at Fortress Mountain, Alberta, and frozen Norton Bay shooting at Lake Abraham, Alberta.
Real shot material
1. Shooting across a frozen lake in Alberta, relying on a lot of roto to complete
The reason why I chose Lake Abraham in Alberta as the location for shooting the unstable frozen lake is that the blue ice here is very clean and clear, and the place is large. It's just that the weather on the day of the shooting was not very compatible. Two days later, the lake was covered with snow. Fortunately, the production team took a lot of reference photos within these two days.
Nearly 95% of the shots are related to the sled dog and the owner Leonhard Seppala. To facilitate production, the entire sled team, sled, protective gear, fur, clothes, and Leonhard Seppala's hair need to be rooted separately, taking into account the sled dog body behind the team The cold atmosphere is stronger than the sled dogs in front, and the roto has to be created in layers.
A real shot of sled dogs, replacing the environment and enhancing the atmosphere
Under normal circumstances, it is sufficient to project the roto layer on the character's body trajectory or vehicle trajectory and then superimpose on it, but at this time the hair details are very complicated. You need to project the roto on the card, build a sled system as a card binding, and then add Each layer of particle FX, snow, atmosphere, etc. In addition, the snow and ice produced by the sled and sled dogs flying forward are simulated in Houdini and filled with some 2D elements.
2. Cracked ice
The design of the ice-breaking lens is very complicated. The live shots were taken on a flat ice surface, so some ice flipped shots can only be done in full CG, while those non-CG shots used a method of destroying the lens track to make the ice surface look more" be more active, limit it to the range that does not destroy the parallax, use 2D techniques to constrain the fixed camera on a floating ice cube, or move the camera on the ice material, add 2D floating, and make the effect look less stable.
Moreover, the material itself was shot on a flat ice surface with different light, and the lighting conditions are constantly changing with time. Therefore, the material of each version is different. It is necessary to keep these materials consistent and guide the ice surface. Fragmenting piece by piece is also a long and complicated process.
3. Simulate huge ice cubes
In the sequence of the sled dog team crossing the frozen lake, huge blocks of ice will gradually rise as the ice surface breaks. The production team used procedural methods as much as possible to guide the shape of huge ice cubes. When there are a large number of huge ice cubes, there is no way to bind each piece individually, and it is impossible to carry out carving, texture, and appearance development processing on each piece. This will limit its shape and size. Once you want to make it If you modify it, you have to go back to the previous step and recreate it. So they created a new Cascade system that allows the layout department and the environment department to create huge ice cube layouts on a shot-by-shot basis.
The Layout department created a very basic proxy shape in Maya and used Maya's curve tool to draw a huge ice shape, stretch it, place it in the scene, add binding constraints, and set up rough animations in the floating ocean.
The environmental team has created a very practical toolset that can procedurally model huge ice blocks through basic geometry, generating broken edge details, internal bubbles, cracks, and faults in the ice layer. With the help of new tools, the work of the production team is basically all day shooting during the day and farm rendering at night.
If you need to change the size or shape of the huge ice cube, go to the Layout link to redraw the curve and give it to the next process. The visual effects link will also simulate the interaction between huge ice cubes and water, including details such as bubbles and splashes, and finally, render in Clarisse.
4. The environment of other mountains
In the film, the growth of Togo is described in the form of memories of Laosai, part of which takes place among the mountains. The production team took a lot of very beautiful mountain views and modified them on this basis. For example, when shooting in Fortress Mountain, Alberta, the director thought the environment was good but there were too many trees, so some processing was done in the later stage. For another example, in the shots of the settlers' houses, there are no Alaska mountains in the real shots, and they need to be added later.
When designing the background, compared to the cumbersome work of drawing a large number of digital landscape maps, the production team adopted a 3D method that combined digital high-modulus, lidar scanning, and photogrammetry technology.
In the end, the mountains that we saw close to the lens were sculpted, textured, and look-dev processes were completed. There were also some Clarisse renderings of trees, leaves, and rocks. In general, there was indeed a lot of background work that needed to be processed.