Ambition

To celebrate the historic landing of the Rosetta space probe on 67P/Churyumov–Gerasimenko, the European Space Agency and Warsaw-based Platige Image collaborated on Ambition, a short film that explores the philosophical questions surrounding our place in the cosmos.

Much like the actual mission, precision and timing were essential components in creating this near seven minute VFX-laden film. With Houdini in their pipeline, Platige Image had a robust set of tools that would help them accomplish much of the challenging VFX work within a tight deadline, in particular features like the triangular-shaped metallic nanobot clouds and the creation and destruction of planets.

The motion of the Nanobots was developed and simulated by Platige’s FX TD Timucin Ozger, who approached this piece using the particle dynamics tools in Houdini. 

The desired look was for the particles to behave as if they were intelligent robots. To accomplish this, he created rules with Houdini to establish their behaviour, defining attributes such as their speed limitations, proximity awareness, and sharing velocities in between particles in order to maintain a steady flow that prevented them also from taking too much of a noisy visual look. This gave Timucin all the control needed for producing exact balance between free form motion and interaction with live actors and the environment.

I was able to create this behavior without having to do any coding” Timucin explains. “Instead I simply used the supplied nodes in Houdini, and by assigning rules within the nodes such as ‘popinteract’, ‘popspeedlimit’, and others I was able to complete my work”.

Mantra’s ability to handle and output any kind of information helped them to generate all the necessary technical passes that were later used extensively by Jakub Knapik, Project Supervisor and Compositing Artist at Platige Image. Working alongside Maciej Jurgielewicz, Platige Image FX Artist, the final look and tech of the nanobots was developed.

“To provide a normal pass, nanobot point clouds were used to generate volumes” explains Maciej who handled the shading and rendering of the nanobots. “The normals were then calculated as a gradient of the density field which allowed us to have enough control over the smoothness and distribution”.

The many planets that are floating around and later crash in the environment that surrounds the live actors were created using a wide range of simulation features within Houdini including the Finite Elements (FEM) solver, packed primitive Rigid Body Dynamics (RBD) for the smaller rocks, FLIP and Pyro solvers supported with regular particle Dynamics (DOPs) for secondary debris and sparks. 

These setups not only existed in the same environment, but they were also driven with an exchangeable set of forces and massive layers of simulation could easily interact with others.

“For Pyro FX, I've come up with a simple setup to seed particles within density volume” says ?ukasz. “For each frame where these reborn particles accumulated, forces would be added to the velocity field and make the Pyro FX act just like any other simulated element. This was important for attraction forces which were easy to customize thanks to the open nature of Particle forces being built using VOPs.”

A deep layer of the earth shown with stirring movement beneath its surface was initially simulated using the Finite Element solver. The result was then used to drive point clouds which have been attached using custom Attribute VOPs. These acted as collision geometry after being converted to signed distance field with VDB. Points that exceeded certain thresholds were then added to the FLIP-Sand simulation which was running on top of it.

“When it comes to pushing massive amounts of data through Mantra, planet creation shots were quite a benchmark” remarks ?ukasz.

The rendering of the planet creation shots consisted of roughly 15GB of cache data per frame, which included 5 different layers of particles for point rendering (growing to around 100 million points), high resolution volumes for dust, core explosions and fire and about 0.5M instances for various rock geometry. This set was lit with standard skylight/HDR and volume lights based on simulated explosions. Shaders for every element were extended a bit to export additional variables for masking and velocity magnitudes.

“Thanks to delayed load procedurals IFD files could be generated in minutes on a single machine” says ?ukasz. “Mantra was very predictable in terms of both quality and scalabity and RAM usage was way below the limit of 32GB inviting to push even harder next time”.

Houdini gave them the ability to accomplish much of their FX work for this project from start to finish, saving them precious time and resources when working under a tight deadline. 

“Being able to remain within the same software package for creating much of the VFX in this project was a benefit above all” says ?ukasz.