Olivier Mercier

Surface Turbulence for Particle-Based Liquid Simulations
Olivier Mercier, Cynthia Beauchemin, Nils Thürey, Theodore Kim, Derek Nowrouzezahrai
We present a method to increase the apparent resolution of particle-based liquid simulations. Our method first outputs a dense, temporally coherent, regularized point set from a coarse particle-based liquid simulation. We then apply a surface-only Lagrangian wave simulation to this high-resolution point set. We develop novel methods for seeding and simulating waves over surface points, and use them to generate high-resolution details. We avoid error-prone surface mesh processing, and robustly propagate waves without the need for explicit connectivity information. Our seeding strategy combines a robust curvature evaluation with multiple bands of seeding oscillators, injects waves with arbitrarily fine-scale structures, and properly handles obstacle boundaries. We generate detailed fluid surfaces from coarse simulations as an independent post-process that can be applied to most particle-based fluid solvers.
Method added to the Mantaflow framework.
Characteristic Mapping Method for the Linear Advection of Arbitrary Sets
Technical Report, arXiv, 2013
Olivier Mercier, Jean-Christophe Nave
In this paper, we present a new numerical method for advecting arbitrary sets in a vector field. The method computes a transformation of the domain instead of dealing with particular sets. We propose a way of decoupling the advection and representation steps of the computations, resulting in significant reductions in computational times over other methods while still guaranteeing accuracy. The decoupling also allows one to advect multiple sets at low computational cost, and makes the method highly parallelizable. Results are presented in two and three dimensions, and accuracy and efficiency are studied.
Numerical Methods for Set Transport and Related Partial Differential Equations
Master's Thesis, McGill University, 2013
Olivier Mercier, supervised by Jean-Christophe Nave
In many cases, the simulation of a physical system requires to track the evolution of a set. This set can be a piece of cloth in the wind, the boundary between a body of water and air, or even a fire front burning through a forest. From a numerical point of view, transporting such sets can be difficult, and algorithms to achieve this task more efficiently and with more accuracy are always in demand. In this thesis, we present various methods to track sets in a given vector field. We also apply those techniques to various physical systems where the vector field is coupled to the advected set in a non-linear way.
Hackathon DIRO 2015
University Of Montreal
A coding event aimed at CEGEP students (16-19 years old) in a computer science (or related) program. The participants had two days to recreate level 1-1 of the original Super Mario Bros. using the provided starting code and graphic resources. All was done using the Processing framework. I was one of the two people in charge of creating the code base. I was also in charge of writting the instructions, building the website, and supervising the students during the event.
Winning Solitaire in Shadertoy
Shadertoy Competition, SIGGRAPH 2015
My entry for the Shadertoy competition at SIGGRAPH 2015, created in about two weeks of free time. See the link to the Shadertoy page and a video of a presentation I gave on this project.
Matrix Row-Column Sampling for the Many-Light Problem
Course Project, 2014
This project is based on the paper Matrix Row-Column Sampling for the Many-Light Problem [Hasan et al. 2007]. The paper shows a way of approximating the contributions of many lights (e.g. 100,000 lights) by using a sampling approach to cluster the lights.
Eikonal Approximation for Real-Time Height Field Caustics
Course Project, 2013
Caustics are a key ingredient to produce believable refractive fluid simulations. However, their complex nature makes them very costly to evaluate accurately. For this reason, caustics are often omitted in real-time applications. In this paper, we present a novel method for creating caustics using the eikonal equation. We focus mainly on underwater caustics created by a water interface represented by a height field, with emphasis on interactive frame rates.
Meshing Fluid Particles Through Houdini
Starting with individual frames of a particle fluid simulation generated by an external source, we import the points into Houdini 13 Apprentice (free), create a mesh around the points, and export the mesh. All frames are processed automatically. We show how to customize the import and export nodes to adapt it to any readable and writable format.