HOW TO SCULPT AN ALIEN
MPC senior Modeller damien Guimoneau shares his top Zbrush tips as used to sculpt alien: Covenant’s neomorph and Xenomorph Creatures
1. Dealing with damage:
We needed to have damage variations for the Neomorph after it had been shot at. I created the bullet wounds on the Neomorph and tried to keep them connected, whilst keeping in mind that the creature was growing from baby to adult in seconds! In Zbrush the Morph target is extremely useful for this kind of thing, you can create all of the damage you want and also restore what you want to keep intact with the Morph brush. It was also interesting to create the thickness of the blood in this model, I then created a mask and passed it on to MPC’S texture artists
2. When you need super-detail:
This is the sculpt I used for the final displacement, showing the muscle fibre and bone detail. The challenge here was to make sure each part was visible and to keep the high frequency detail for the texture pass in Mari. I used a lot of masks; most of the time, the muscle fibres were created with a standard brush with a small Lazysmooth. Masks are useful to create layers of muscles and a realistic border between the different muscles. A final pass with Nuke and Mari allowed us to add some sharpness and really fine directional lines.
3. The fine art of handling hands:
Late in production, we discovered that we were going to have some extreme closeups of the hands (the famous shower scene that happens when the characters appear to have been saved is one specific example). We decided to merge the Zbrush sculpt subdivision 2 to the arm to create greater detail even in the base model. This image is a work in process of the sculpt I worked on for the hand. It’s also a good example to highlight that not all of the details come from Zbrush. Efficient maps of realistic hand wrinkles will add the final touch in texturing.
4. Reference and iterations:
We’d used very interesting, creepy and even comical references for the Neomorph, including an incredibly grumpy cat for skin reference as the tones of its wrinkly skin was perfect. The goblin shark was also incredibly helpful for its horrific protruding mouth. Additionally, we worked with contortionist and actor Javier Botet who is extremely flexible and long limbed. The back of the Neomorph was a challenge because the decision on how long the spikes should be changed quite a few times! We even had a pass of retopology late in production.
map, which was quicker and more controllable.”
MPC’S modelling team provided a simple plane for each scale. These planes were wrapped to a cut-out of the pangolin’s body, which had a skin cluster assigned to it. Adds Wagner: “Aside from driving the planes, the body is also wrapped to this object. This causes the body to push in and out, following the cutout and therefore scale movement and avoiding intersections.”
Wagner added a deformer to the pangolin to push out the tips of the scales slightly when the volume was compressing, say for moments when animation was curling the character. The result was that the lighting hit the rigid parts differently to reveal shadow and depth. An in-house collision deformer was added that collided with the scales based on hierarchy assigned to the relevant objects.
Then, using the walk animation, Wagner defined smooth and rigid body areas to transition between the torso and limbs of the pangolin. “To add more interest to the character, I added dynamic softness and bounce around the belly area, which gives a sense of fat and secondary animation. On top of this I ran a deformer detecting the edge lengths of the body mesh to add wrinkles on the skin around compressing areas in motion.”
The big test came when the pangolin needed to go into its curl pose, since that’s when the scales would be at their most interactive. “Using this pose I was able to test attributes across multiple deformers quickly,” says Wagner, “and I used playblasts to wedge values and find the right one to use. Wedging attributes on a character in a separate Maya session is something I do across all of the different characters I work on. I always have a scene with a light rig playblasting in viewport 2.0 – to see how light and shadow hit the skin – to test different settings on a character in motion.”
FUR REAL
MPC lead groom artist Gabriel Arnold helped deliver the exquisite fur coat on the tiger Shere Khan for The Jungle Book, a task that involved co-ordinating a growing groom team and dealing with software updates for the studio’s in-house grooming software Furtility. Furtility is a plugin for Maya that allows MPC to add fur onto hero characters in Katana,
large crowds of characters with reduced fur counts and even feathers onto birds. Occasionally Xgen is also used at MPC to create guide curves.
Shere Khan’s groom began with the design of the character, with MPC working from a clientsupplied style guide plus a rough digital sculpt. The modelling department then sculpted Shere Khan which, once approved, was retopologised so it would deform well when animated. Then it was passed to the groom department. The groom itself was done by senior artist Sohrab Esfehani.
“For Shere Khan, the idea of the design was for him to look menacing and intimidating,” says Arnold. “Tigers are beautiful animals and some of them looked too nice for the character of Shere Khan, so we had to look for references of tigers that were dirty and had been in fights. The fur coming off the cheeks needed to be dank and knotted so we even looked at dreaded human hair to study the look of it and incorporated this into the look.”
Another significant element of Shere Khan’s design were the scars on his face, which needed to be ‘gnarly’ but not overly gruesome. “From the references we found of tigers that had scars on their faces,” details Arnold, “we found that the skin would go darker as the wound got older, and also a small amount of fur would start growing back especially round the edges of the scar, so we edited the maps we received from texturing in Nuke to get some fall-off at the edges of the scars.”
The dynamics for Shere Khan’s fur were then handled by MPC’S technical animation department, which utilised another plugin for Maya called mpcsolver (since The Jungle Book, Houdini has also been employed to make use of some of its features, such as plasticity).
“mpcsolver works by taking a percentage of curves, which are saved out as a cache when we release our static groom, and places them onto the animated mesh,” describes Arnold. “These curves are then simulated after applying dynamics settings and cached out. The cached simulation is then packaged up to use in the pipeline and brought into Katana to render with Renderman. At render time the fur gets wrapped to the cached dynamics simulation. mpcsolver can also be used for doing crowd dynamics.”
LOOKDEV FOR A LIVING, BREATHING CG HUMAN
Axel Akesson was asset supervisor for Blade Runner 2049, where MPC worked on a fully digital asset for Rachael. One of his core tasks was lookdev’ing the CG version of the character against actress Sean Young from her performance in the original Blade Runner from 1982.
“For the build of Rachael we collected a lot of reference of Sean Young from the early Eighties and then created CG cameras to match the footage as closely as possible,” says Akesson. “This allowed us to check our 3D model against the reference images and work it to match everything. These cameras were used in all departments from modelling to lookdev.”
The team also captured USC ICT Light Stage scans of Sean Young as she appears now and a performance double, Loren Peta,
whose body appears in the live action scenes. “This gave us very detailed 3D models of both Sean and Loren,” adds Akesson. “Loren was captured in the Light Stage with 290 LED lights, one light turning on per frame. This was excellent reference for how the skin behaved, and we re-created the ICT Light Stage in CG so that we could work on our digital Loren until we got the skin to match pretty well. This was then transferred to our 1982 Rachael digi-double and tweaked from there.” For the final shots in Blade
Runner 2049, the lookdev and lighting process – which was carried out via Katana and Renderman – also included matching the on-set lighting which was situated amongst a set of reflection pools. This was a significant challenge because almost none of the lights were static. “The main lights were on two massive rotating rings in the studio ceiling slowly turning around,” states Akesson. “So we had to carefully survey how this rig worked on set in order to recreate it in CG.”
Lookdev is all about proving the asset can work in a scene – and tweaking it – so MPC actually re-created a few shots from the original film with its CG Rachael first. Says Akesson: “The test shots had different purposes, for instance, to match the emotional performance, to perfect the peach fuzz covering her face, matching her makeup and so on. It was an excellent way of really making sure that our digital Rachael was believable and worked in a moving shot context. A really important thing for me was to re-create the way light refracts in the cornea of the eye and then hits the iris. This phenomena is called caustics and it’s the key to photorealistic eyes. Since we were trying to do a very subtle and emotional performance with our digital Rachael, it was extremely important that the eyes felt real.”