At the beginning of the year I joined Pixomondo Berlin to work on custom solvers as well as to integrate ExoticMatter’s Naiad state-of-the-art fluid solver in to the feature film division’s pipeline.
Read the case study and interview with VFX supervisor and Head of Technology Mohsen Mousavi.
Just arrived back in Sydney to rejoin with Animal Logic’s R&D department and work on amongst other projects “Walking With Dinosaurs 3D”.
From January to May I worked at Pixomondo Berlin on in-house libraries as well as custom and commercial fluid solvers for Red Tails and Journey 2: The Mysterious Island.
Instead of relying on explicit definitions (e.g. of collision geometry), the framework makes extensive use of implicit surface descriptions. This data tells much more about an object in space and allows for a substantial set of features including very efficient collision detection and response, normal and volume retrieval, level sets (for boundary particles, lego brick generation or filling objects), as well as filtering and meshing of volumes, for instance. Continue reading ‘Regular and adaptive signed distance fields’
Friction and attraction forces can only produce granular effects up to a certain limit. To simulate piling and other interesting stacking effects, spherical particles need to be replaced by more complex structures and shapes. Particles hence need to become rigid bodies. In the provided video each particle becomes the centre of mass of a pyramidal shape represented by four surrounding lightweight particles. Continue reading ‘Rigid Body Particles’
Instead of applying forces based on springs, stiff connections are introduced to account for attributes of inextensible cloth. The constrained structure is relaxed in an iterative manner to converge to an optimal solution. Bend and shear connections can optionally be weighted to allow for different material behaviours. Virtual particles are placed on the centre of each edge and face for detailed self collision. Non planar rest shapes allow for hand crafted folds and wrinkles which retain throughout the simulation. Alternatively, parameters can be set to learn or forget rest shapes depending on elapsed time and/or bend angle thresholds. This does not only result in more realistic behaviour, but also tends to stabilise the simulation.
Temperature (colour coded on the left) is diffused using the SPH approach. Per particle user defined conductivity values allow for a controlled melting process while an ambient temperature and conductivity is cooling the particles down. The viscosity of the particles is directly influenced by the temperature. Hotter particles receive a lower viscosity, i.e. they flow more freely and quickly, while colder particles move with a higher viscosity. Continue reading ‘Heat Diffusion and Viscosity Adaption’
Implementation of the PCI SPH algorithm from B. Solenthaler et al. (vmml.ifi.uzh.ch/files/pdf/publications/pcisph.pdf).
An explicit foam handling allows for the generation of foam based on velocity or vorticity. Fluid particles are transformed into foam particles with user defined distinct rest density and viscosity. This makes it possible to have water interact with foam particles. To restrict the foam to the fluid-air interface, foam particles can be filtered by the magnitude of the colour gradient.
Continue reading ‘Predictive Corrective Incompressible SPH’
Honey like fluids using a combination of springs and SPH, integrated using a predictor corrector scheme, to allow for high viscosity and high surface tension. SDF based collision detection and response with an additionally applied boundary force to simulate stickiness.
Viscous, plastic, elastic and tearable materials are modelled using various kinds of springs, and iterative approaches to allow for stable high viscosity and surface tension. The spring types include simple force based or stiff springs initialised at start time, dynamic springs which are created at simulation time (between close by particles), springs with adjustable rest lengths (von Mises yield criterion), as well as springs tearing depending on user defined thresholds (change in velocity, etc.).
DEM particle simulation using a predictor corrector scheme.
Inter-particle collision detection is accelerated using a uniform hash grid. Signed distance field based object collision detection and response. Surface normals (for particle placement and friction effects) are interpolated from the distance gradient of the field. Features damping, shearing as well as dynamic and coloumb friction effects.
In the spare free time, I am working on a particle based multi-physics solver to simulate granular, viscous or fluid materials as well as cloth and rigid bodies.
Continue reading ‘Working on a multi-physics solver…’
For Sydney based Animal Logic I had the pleasure to work as an R&D software developer on their upcoming animated feature “Legend of the Guardians” directed by Zack Snyder. It is a tale of adventure of owls, based on the fantasy book series “Guardians of Ga’Hoole” by New York Times bestseller Kathryn Lasky. So look forward to seeing an amazing block buster with good owls, bad owls, dog fights and lots of feathers–in eye-popping 3D, of course.
Continue reading ‘Legend of the Guardians’
For the animated short “Lost and Found” created by Studio aka I developed a plugin to generate deforming ocean surfaces and foam layers. The story is based on Oliver Jeffers award winning children’s book and directed by Philipp Hunt.
Continue reading ‘Lost and Found’
At Def2Shoot, Paris, I worked in the R&D team on the animated feature “Yona Yona Penguin” directed by Rintaro.
Continue reading ‘Yona Yona Penguin’
