MPC is a great company to work for. They have outstanding in-house tools that help us achieve things that aren’t possible with the standard 2D/3D packages. This helps us push the boundaries of what is possible for each show. Our supervisors Charley Henley and Matt Middleton also have a very high standard in the approvals process. Finally Prometheus had already gained so much hype that all of our team members were hugely excited by the project and gave their very best.
MPC has a wide variety of in-house tools that are very useful, such as Giggle which is our own proprietary sets of tools and libraries based in Lua scripting language. Kali is no exception to this rule; it’s a whole framework and toolset based over Pixelux’s DMM solver.
The solver is not RBD based (Rigid Body) but instead uses FEA (Finite Element Analysis). It allows us to work on destruction simulations without the need of pre-cutting/pre-braking the objects beforehand and allows us to manipulate bendy, squashy or cloth-like objects as well. On a production standpoint the best thing it offers is having Assets and FX working in a more parallel way instead of sequentially. FX does not need to have the final model, as we do not work on the actual model directly.
Basically how our Kali pipeline operates is like this; we create a low detail version of the current model, trying to simplify it as much as possible. This low detail model has to ecompass the actual model as this will be used later on to “Chop” the actual render model. Once the low detail version of the model is completed, we simply tessellate it using Kali’s tessellation tools. This gives us the actual simulation geometry that we use in FX. From here on we communicate with the DMM solver through an extensive event based system. We’ve got a whole library of events ranging from enabling disabling objects to changing the properties of objects based on velocity, age or force. With MPC’s pipeline it’s easy for any TD to write his/her own event in Giggle, helping us to maintain control of the simulation in any given situation. Once we have this cache done we use it to chop the actual render geometry. A very simple explanation would be that it acts like a boolean/cookie and applies a wrap deformer on the actual render model.
On Prometheus we used Kali mostly on the Prometheus crashing into the Engineer’s ship in slow motion. It enabled us to have the nose of the ship bend, crumble and tear apart. The ship was very heavy to render and with Kali it was even heavier. To optimize we only used a third of the ship as it quickly gets engulfed in an enormous ball of flame, so no additional simulation was needed afterwards.
We also used Kali on the “Pinnacles” – those pointy rocks that were scattered all over the planet surface. The rolling Engineer ship squashes a few of them and the Vickers Survival Module hits one while landing. We used Kali to get the Pinnacles to crumble and break.
The ship crash and rolling were quite heavy sequences to work on as there were so many elements to create. In FX the initial impact was created in Kali, but we also added additional particles and particle instances to make the whole effect richer. The explosion was done using Flowline, which is Scanline’s fluid solver. Flowline is great for extremely heavy fluid simulations. We made the explosion interact with the ships so it wraps around them. We also added additional debris and lighter smoke trails using Maya. To make the explosion look more photo-real we mixed in real live elements into the rendered explosion elements to give it the final impressive look.
Next came the sequence of the Engineer’s ship. This consisted of mostly the same FX elements as across all the shots. We had falling debris that came from the Prometheus’s explosion that rained down and hit the ground, which created small impact explosions. We had built a library of these and we then placed and timed them according to where and when the debris would hit. Some of the debris was flaming and had to leave a trail of smoke behind it, which we generated using Flowline or Sprites depending on the situation. Some of that debris also had to bounce off the Engineer’s ship. For this ship interaction we generated smoke, rocks, and particles at the intersection point. As with the explosion, live elements were also mixed in at the compositing stage on top of the FX layers to give it a more photo-real look.
The shots of the initial impact when the Engineer’s ship hits the ground after crashing into the Prometheus was mainly created using live shot elements and additional layers of FX rocks, smoke and sprites. The live elements, although very good, weren’t sufficient and we went on to create a particle/sprites shockwave and added small ground rocks and particles being thrown out by the supposed pressure generated by the impact. Once mixed in with the live elements, it created a grittier, more realistic look. Scale was also a major factor to look out for as the Ship had to look massive. We couldn’t have anything that would move too fast or that would project too far as it would have thrown off the ship’s scale.
For the rest of the crash sequence we were lucky that it was shot in a very ‘ledgy’ environment in Iceland. What I mean by that is that for most of the shots there was a ground ledge between the audience’s point of view and the ship. This gave the impression of connection between the ship and the ground much easier to achieve as we rarely see the ship interacting directly with the ground.
However, there were also a couple of shots from an aerial view of the rolling ship. These were a bit trickier as these were the shots where the interaction was the most visible. Wee treated these shots more independently. We created thick volumetric smoke that would billow out from the intersection of the ground and the ship, rolling slow enough to keep the scale of things right and keep the detail of the plumes quite high.
These sequences were done in roughly five-six months, but even longer considering the initial preproduction. In FX we were around 20 at one point split between two teams, with ten in the team that worked on the crash sequence. If we were to include all the other departments – Asset / Texturing / Layout-Previs / Matchmove / Roto-Prep / Rigging / Animation / Environment/ FX / Lighting / Compositing / Production – I’d say around 60-70 people.
Having had the opportunity to work on a Ridley Scott project is quite an honour. I’m very proud of what the FX team achieved on this show, the explosion shots look great and the whole crash sequence is very effective.
On a more personal FX artist note I’m also very happy at how the Prometheus thrusters ended up looking, as I did the FX setup work for them.