Computer Graphics World

Edition 1 2018

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e d i t i o n 1 , 2 0 1 8 | c g w 4 1 Sometimes, the transition between suit and CG occurs many times over during a sequence. For instance, when the creature is suffocating in the bath tub, the group cuts between a close-up of a 70 percent practical suit to full CG and back again several times over the se- quence. The shots required the creature to pull water into his gills, churning up the bath water, while covered in a layer of algae, scales, and blood. In those instanc- es, the entire shots are CG, including the bathtub and water, as are several shots when Elisa meets the creature in his tank in the lab and whenever he's swimming underwater. This includes when his tank is being rolled into the lab, and in the final sequence of the film. In those instances requiring a CG creature, the Mr. X team would use Jones' physical performance as a base for the facial animation, guided by scans of the actor out of suit in a set of FACS facial poses, which were then sculpted and mapped to the creature. (Mr. X used an in-house scanning system called X-Scan, which consists of approximately 80 DSLR cameras; it can be reconfigured for hero facial scans as well as full-body scans.) The scans were used as a guide to sculpt the creature's blendshapes and guide the wrinkles on his face. The team also developed a tension map workflow that allowed Alembic data chan- nels to drive animated displacements and capillary action – allowing for fine wrinkles and skin bunching as well as subtle blood flow effects in his nose and muzzle area. Because the suit itself fit differently and would wear differently each day on set, constant paint touch-up was required by the digital team when it was in contact with water in particular. Explains Trey Harrell, digital effects supervisor, "One of our major challenges was presenting a consistent, idealized version of the amphibian man that was always on-model, regardless of the fit or state of the suit on a given day. We had a three-stage facial tracking pipeline that allowed for differences in fit of the facial area of the suit. We'd begin with a rigid track, focusing on his eye silhouette entirely, and then we'd adjust the fit of the digital mask and makeup appliance to match the stretch, compression, and fit of the practical face area on the day. Aer animation, we would go back in and tweak the silhouette so that the creature would be in line with Guillermo del Toro's ideal." For the VFX work, Mr. X used Autodesk's Maya for modeling and animation, as well as Side Effects' Houdini, with the studio's custom path tracer and in-house Cryptomatte extensions inside of Side Effects' Mantra for the simulation and lighting pipeline. The custom path tracer and Cryptomatte extensions allowed for clean matte extraction of primary rays through arbitrary reflection and refraction depth. The artists also extended their custom Mantra SSS model to allow for the separation of per-light contribution, now available in off-the-shelf Houdini. Compositing was completed in Found- ry's Nuke. The rest of the pipeline compris- es fairly standard tools: Science.D.Visions' 3DEqualizer for tracking, Foundry's Mari for texturing, Pixologic's ZBrush for sculpt- ing, and initial hair grooms that would be finished with Peregrine Labs' Yeti before being exported as dense guides for simu- lation and rendering in Houdini. UNDERWATER CHALLENGES Both the creature and Elisa spend a large portion of the film under or in contact with water. Much of the film contains two types of digital water. The first type is a conventional fluid simulation, used for the sloshing river water in the tank and the bathtub water when the creature is suffocating. The other effect is based on classical dry-for-wet photography tech- niques whereby the actors are suspended on wires on an especially smoky stage. All of the water effects were created in Houdini, using FLIP fluid simulations where there is a visible water surface. For the dry- for-wet underwater sequences, particulate was created with particle sims, whereas bubbles were FLIP sims. They were all af- fected by a common vector field along with underwater grass, props, Elisa's hair, and the creature's fins. To allow for rapid sim iteration for most of the hero fluid sims, the effects TDs developed a toolset that would allow individual simulation frames to be diced up and distributed through Mr. X's local and cloud-based render infrastructure. NOT YOUR FATHER'S MONSTER MOVIE "The Shape of Water is easily my favorite project I've worked on to date, both as an artist as well as a guy who just loves cinema in general," Harrell says. "I've seen the film dozens of times in various states, and I still get weepy at a few key moments in the film – that never happens." Harrell is a firm believer that more isn't always, or even usually, better. "Spectacle will only get you so far if you don't connect with your audience emotionally as a story- teller and filmmaker. The Shape of Water combines the best of both practical and CG effects – but we don't want the audi- ence to know it's an effect. We want to get out of the way and let the viewer become enraptured in the world and story." Karen Moltenbrey is the chief editor of CGW. Images ©2017 Twentieth Century Fox Film Corp.

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