The Man In The High Castle Compositing Breakdowns
In the season 4 finale of the show The Man In The High Castle, Stormborn Studios was tasked with 9 complex VFX shots in which an explosion causes a Nazi train to derail into a snow covered environment. For this project we collaborated with Barnstorm VFX who was providing assets and animation for us to get started. Being a small studio, the sequence which included a combination of rigid body dynamics, volumetric, grain and particle simulations posed many challenges to overcome.
In addition to that, Stormborn delivered a shot for the first episode of the season, in which the character Nobusuke Tagomi disintegrates into ashes in a dream like sequence.
We tackled the first challenge of limited resources by leveraging Redshift's new GPU rendering technologies. With only 9 machines and licenses, we were able to build a render farm with the power of 21 render nodes, since GPU rendering allows for multiple graphics cards within a single workstation. GPU rendering also helped us to keep our rendering times significantly low compared to other processor based solution like Houdini's Mantra render engine.
Using Houdini, this setup managed to render within a single shot over 100 million snow and dirt particles together with high detail geometry and a multiude of high resolution volumetric smoke or snow dust caches. In terms of complexity more than 160 heavy volume caches were generated throughout the entire sequence (explosions, snow, mist, steam, etc.)
Stormborn's inhouse farm submission tools allowed our artists to split the large scale environments into multiple sections in order to keep simulation times low and ensure quick turnarounds. This process is usually referred to as clustering or wedging. The high speeds of the derailing train caused it to cover a long distance, so wedging the snow, dust and smoke simulations helped to keep simulation times and cache sizes small, while allowing the artists to output a lot of iterations. The jet engine powered train traveled at a speed of around 200km per hour which made simulating our elements extremely difficult. In some situations our artists animated the train backwards in one axis in order for it to travel at a slower speed. Then simulated their FX elements, and then re-transformed those back into world space to match the original train animation.
The next hurdle to overcome in the production was to progressively destroy the train and carry over destruction states of the train geometry from one shot to the next. Requirements for the destruction setup were to be able to bend, deform and tear metal, as well as simulating additional passes of secondary destruction such as objects breaking off and flying away.
Senior FX Technical Director Andrew Graham was in charge of building this setup by leveraging Houdini's Bullet Physics Engine, its Procedural Dependency Graph (PDG) as well as his proprietary cloud submission software Open Firehawk. The system built a procedural cage comprised of simple boxes to approximate the train geometry and was capable to simulate around 160,000 bending and tearing elements per train wagon. This allowed the artist to have quick iterations to which secondary simulations were added on top, such as rattling metal objects and cables that were simulated with Houdini's Vellum Solver. Senior FX TD Jacys Cheng-Yu Lin was in charge of adding an extra layer of art directable metal deformation to the train in some of the shots which allowed for quickly addressing specific client notes.
In order to make the CG action of the derailing train believable, dirt and snow had to be kicked up in ample amounts whenever the train collided with the snow and dirt environment. Ballistic projections of snow and dirt with the high speeds of the bullet train required a hybrid system of RBD and particle simulations developed by senior FX TD Arthur Graff. This sophisticated FX rig allowed to preserve complex earth and snow structures created on the train's collision with the environment.
First a constrained rigid body pass simulated with Houdini's Bullet Solver would break on the impact of the train and result in an initial rough trench shape with projectiles comprised of dirt clumps and snow chunks bouncing off the train.
Simulation tests for the final destruction shot in which the derailed train slowly comes to a halt
Then, based on speed and pressure, the rigid bodies would turn into a position based particle model. The grains would give intricate details and add an extra layer of fracture. A typical shot would have snow and dirt particle counts of roughly 50-100 million points. Finally, on top of this main particle pass we added another fine particle pass to fill some gaps and render the simulation even more powdery. Several layers of mist and smoke generated by VFX Supervisor Manuel Tausch blended the particle elements together in order to reach a high level of realism.
Last but not least the train track had to be blown up and destroyed in order to trigger the derailing sequence. Manuel Tausch simulated the initial volumetric explosion and resulting residual smoke plumes by using Stormborn proprietary tools that leverage Houdini's Pyro Solver. VFX Supervisor Goran Pavles took care of pre-breaking the train track's geometry and simulating concrete fracturing and falling debris chunks in a constrained rbd setup. A highly art directable bespoke cutting tool allowed to generate realistic concrete shapes that were then simulated in a physically based RBD solver. Senior FX Technical Director Ahmad Ghourab assisted in simulating layers of dust emitted by the cracks of the broken concrete.
Apart from running RBD simulations, Goran Pavles simultaneously took charge of lighting and rendering all FX elements for the entire sequence. Since Barnstorm VFX was compositing the sequence and responsible for rendering the environment and the main train asset, we had to establish a smooth workflow between the two studios animation, lighting and compositing department.
Our studio was receiving the train asset geometry from the client, and had to match the shaders on the clients side for reflections and refractions. Would then send back a newly animated, defomred and destroyed asset for the final rendering. Additionally, we would render all FX-elements on our side with Redshift. Therefore we had to come up with an additional solution for shadows, reflections and refractions. Together with Barnstorm's comp department, we established a workflow that would let them integrate the FX elements properly into their comp.
Finally, with so many different FX caches, renders and versions, we had to come up with an organized way of sharing and categorizing this data. We put a database together that the client could access, filter and sort by shot, and see when and which elements and versions have been delivered.
Stormborn simulates the ash disintegration of MITHC protagonist Nobusuke Tagomi
Besides handling the train destruction sequence for the final episode of season 4, Stormborn was tasked to take care of the disintegration of protagonist Nobusuke Tagomi in the season's opener. In this episode Juliana Crain has a dream like vision of Tagomi, in which the latter dissolves into layers of ashes and fades away. Manuel Tausch and FX Artist Jesper Rahlff collaborated in generating the required Houdini setups and FX elements.
Tagomi's matchmove geometry would be broken into thousands of pieces of geometry which then were constraint to the animation of the matchmove. A procedural particle system would trigger the release of the ash flakes, which were then flying away controlled by wind forces and noise fields.
Additional layers of smoke and particles were added to allow for a high level of detail. In order to render the effect, the plate was reprojected onto the fractured geometry in a complex shader that permitted a multitude of age-and noise based AOVs. Initially the art direction was to burn Tagomi into embers that turn to ash flakes over time, the client later decided to simplify the look and remove all glowing elements of the setup.
The compositing for this shot was done by CVD VFX.
Client
Team
VFX Supervisor
VFX Supervisor
Senior FX TD
Senior FX TD
Senior FX TD
Senior FX TD
FX TD
Goran Pavles
Manuel Tausch
Ahmad Ghourab
Andrew Graham
Arthur Graff
Jacys Cheng-Yu Lin
Jesper Rahlff