Set against the backdrop of Arrakis, a desert planet, Dune required VFX work that spanned massive and meticulously detailed FX simulations, sweeping environments, full-CG vehicles and creatures to bring the dystopian atmosphere to life on-screen. The VFX experts charged with bringing Director Villeneuve’s immersive vision to life were the team at DNEG who contributed to 28 sequences and nearly 1,200 VFX shots of the film’s 1,700 total.
One of many incredible VFX sequences in the movie was the Sandworm Harvester Attack Sequence. We spoke to Dune CG Supervisor Rhys Salcombe to find out how this was created and rendered using Clarisse.
Can you tell us how you created the Sandworm Harvester Attack Sequence?
Even though the worm only appears fairly briefly in the film in terms of screentime, we knew it loomed large over the project and was the thing many were most excited to see. After receiving an approved design from the art department, and a concept sculpt as a starting point, one of the first things we needed to do was figure out how to make it move!
The worm’s skin is covered in hardened and irregularly spaced plates which makes any kind of volume preservation very difficult as the worm flexes or if it tries to close its mouth. The plates collide or the skin between them stretches beyond breaking point, and since the overall mouth design has a tube shape, the mouth would either need to close with a pucker, which was visually unappealing, or in a way that was a little more ‘anatomical’ than we were looking for. We ended up thinking of the plates more as ‘scabs’ and giving them a roughly 85% rigidity rather than being totally solid. Combined with extremely folded skin between the scabs, referencing elephant skin, this gave the lip circumference enough flex to taper to a close. Although we don’t see the worm close its mouth in the film, this was the driving factor in the fine design detail of the high resolution asset sculpt.
Build lead Jon Catapia needed to sculpt the worm in ZBrush HD geometry over the entire creature for it to fit within RAM, and we had three levels of resolution for the mouth & throat, lips to saddle and tail based on the areas seen in the most screen space. Baked displacement was used to generate mesh data inside Clarisse, so that all of the occlusion curvatures could be used in texturing. And much of the texturing was done procedurally within Nuke so that the textures could be batch processed, leaving more time to refine the sculpt itself. Additional sand surface textures were based on world coordinates so that sand accumulated between scabs and in folds of skin, as well as a dusty coating on the worm’s top side.
The worm’s teeth were modeled on a whale’s baleen, with hundreds of instanced teeth pulling from six base asset variants and arranged radially inside the mouth. Since there were so many teeth the gum intersection geometry was done procedurally in Houdini and merged back into the main asset. That many teeth also made the rig too heavy to work with, and so animation worked with a poly-sheet proxy and in CFX that sheet’s position and deformation re-instanced the teeth into their sockets based on a Houdini point cloud, and the deformation was matched using blendshapes. The most difficult part to resolve was self-intersection of baleen (the filter-feeding system inside the mouths of baleen whales) when the mouth opened or closed, as they tended to collapse in on themselves. This was rectified to some extent by adding the ability to flatten the teeth in rows, pivoting from their contact point with the gum, and then shot-sculpt for any issues that remained.
One creative and technical challenge that was in many sequences we worked on for Dune, but particularly in the Harvester rescue sequence, was the Ornithopter wings. The three Ornithopter variants seen in the film have eight, six and four long metal wings which flap very rapidly like a dragonfly and the director loved the idea that they look like a completely smooth blur when in flight, as if the flight is effortless. Although it’s hard to tell in the film because they move so fast, the wings don’t move in a linear up and down motion, and instead move in a figure eight with shifting pitch through the cycle. This is because the slightest tweak to the animation had huge visual impact once rendered with true motion blur and it took many, many tests to get a suite of settings which had the desired look consistently. To avoid strobing, the majority of our Ornithopter wings ended up being cached from animation with eleven subframes and rendered with thirteen motion blur samples and the final sampling quality needed to be high to get the blur noise free. The shifting built into the wing cycle caught glints and reflections and shimmered when changing angle to allow the vehicle to change direction, which wouldn’t have been possible without those subtleties in the motion or with a screen space blur. A true 3D solution also gave us complex interaction with FX smoke and dust which fed into deep holdouts, as well as accurate shadowing.