Droplets, splashes and sprays: highly detailed liquids in visual effects production.

An often misunderstood or under-appreciated feature of the visual effects pipeline is the sheer quantity of components and layers that go into a single shot, or even, single effect. Liquids, often combining waves, splashes, droplets and sprays, are a particular example of this. Whilst there has been a huge amount of research on liquid simulation in the last decade or so, little has been successful in reducing the number of layers or elements required to create a plausible final liquid effect. Furthermore, the finer-scale phenomena of droplets and sprays, often introduced in this layered approach and crucial for plausibility, are some of the least well catered-for in the existing toolkit. In lieu of adequate tooling, creation of these elements relies heavily on non-physical methods, bespoke setups and artistic ingenuity. This project explores physically-based methods for creating these phenomena, demonstrat- ing improved levels of detail and plausibility over existing non-physical approaches. These provide an alternative to existing workflows that are heavily reliant on artistic input, allowing artists to focus efforts on creative direction rather than trying to recreate physical plausibility. We explore various approaches to increasing the level of detail captured in physically-based liquid simulations, developing a collection of tools that improve existing workflows. First, we investigate the potential of a re-simulation approach to increasing artist iteration on fluid simulations using previous simulation data. Following this, a novel droplet interaction model for ballistic particle simulations is developed to introduce higher levels of detail in simulations of liquid droplets and sprays. This allows physically-plausible interactions between droplet particles to be modelled efficiently and helps to create realistic droplet and spray behaviours. Then, to maximise the quality of the results of these and other particle-based simulations, we develop a high quality particle surfacing algorithm to handle the varied nature of inputs common in production. Finally, we discuss the development of an expression language to manipulate point and volume data commonly used in creating these simulations, as well as elsewhere throughout visual effects. This research was driven directly by production requirements in partnership with a world- leading visual effects studio, DNEG. Projects have been developed to immediately integrate into production, using efficient, industry-standard, open technologies such as OpenVDB. It is shown that the toolkit for splashing liquids, even at fine-scales, can be improved by incorporating greater physical motivation further demonstrating the importance of physical simulation in visual effects and suggesting effects similarly reliant on artistic input (e.g. character/skin deformation) may benefit from increased physical correctness

Working With Incremental Spatial Data During Parallel (GPU) Computation

Central to many complex systems, spatial actors require an awareness of their local environment to enable behaviours such as communication and navigation. Complex system simulations represent this behaviour with Fixed Radius Near Neighbours (FRNN) search. This algorithm allows actors to store data at spatial locations and then query the data structure to find all data stored within a fixed radius of the search origin. The work within this thesis answers the question: What techniques can be used for improving the performance of FRNN searches during complex system simulations on Graphics Processing Units (GPUs)? It is generally agreed that Uniform Spatial Partitioning (USP) is the most suitable data structure for providing FRNN search on GPUs. However, due to the architectural complexities of GPUs, the performance is constrained such that FRNN search remains one of the most expensive common stages between complex systems models. Existing innovations to USP highlight a need to take advantage of recent GPU advances, reducing the levels of divergence and limiting redundant memory accesses as viable routes to improve the performance of FRNN search. This thesis addresses these with three separate optimisations that can be used simultaneously. Experiments have assessed the impact of optimisations to the general case of FRNN search found within complex system simulations and demonstrated their impact in practice when applied to full complex system models. Results presented show the performance of the construction and query stages of FRNN search can be improved by over 2x and 1.3x respectively. These improvements allow complex system simulations to be executed faster, enabling increases in scale and model complexity

Multi-Scale Models to Simulate Interactions between Liquid and Thin Structures

In this dissertation, we introduce a framework for simulating the dynamics between liquid and thin structures, including the effects of buoyancy, drag, capillary cohesion, dripping, and diffusion. After introducing related works, Part I begins with a discussion on the interactions between Newtonian fluid and fabrics. In this discussion, we treat both the fluid and the fabrics as continuum media; thus, the physical model is built from mixture theory. In Part II, we discuss the interactions between Newtonian fluid and hairs. To have more detailed dynamics, we no longer treat the hairs as continuum media. Instead, we treat them as discrete Kirchhoff rods. To deal with the thin layer of liquid that clings to the hairs, we augment each hair strand with a height field representation, through which we introduce a new reduced-dimensional flow model to solve the motion of liquid along the longitudinal direction of each hair. In addition, we develop a faithful model for the hairs' cohesion induced by surface tension, where a penalty force is applied to simulate the collision and cohesion between hairs. To enable the discrete strands interact with continuum-based, shear-dependent liquid, in Part III, we develop models that account for the volume change of the liquid as it passes through strands and the momentum exchange between the strands and the liquid. Accordingly, we extend the reduced-dimensional flow model to simulate liquid with elastoviscoplastic behavior. Furthermore, we use a constraint-based model to replace the penalty-force model to handle contact, which enables an accurate simulation of the frictional and adhesive effects between wet strands. We also present a principled method to preserve the total momentum of a strand and its surface flow, as well as an analytic plastic flow approach for Herschel-Bulkley fluid that enables stable semi-implicit integration at larger time steps. We demonstrate a wide range of effects, including the challenging animation scenarios involving splashing, wringing, and colliding of wet clothes, as well as flipping of hair, animals shaking, spinning roller brushes from car washes being dunked in water, and intricate hair coalescence effects. For complex liquids, we explore a series of challenging scenarios, including strands interacting with oil paint, mud, cream, melted chocolate, and pasta sauce

Animated surfaces in physically-based simulation

Physics-based animation has become a ubiquitous element in all application areas of computer animation, especially in the entertainment sector. Animation and feature films, video games, and advertisement contain visual effects using physically-based simulation that blend in seamlessly with animated or live-action productions. When simulating deformable materials and fluids, especially liquids, objects are usually represented by animated surfaces. The visual quality of these surfaces not only depends on the actual properties of the surface itself but also on its generation and relation to the underlying simulation. This thesis focuses on surfaces of cloth simulations and fluid simulations based on Smoothed Particle Hydrodynamics (SPH), and contributes to improving the creation of animations by specifying surface shapes, modeling contact of surfaces, and evaluating surface effects of fluids. In many applications, there is a reference given for a surface animation in terms of its shape. Matching a given reference with a simulation is a challenging task and similarity is often determined by visual inspection. The first part of this thesis presents a signature for cloth animations that captures characteristic shapes and their temporal evolution. It combines geometric features with physical properties to represent accurately the typical deformation behavior. The signature enables calculating similarities between animations and is applied to retrieve cloth animations from collections by example. Interactions between particle-based fluids and deformable objects are usually modeled by sampling the deformable objects with particles. When interacting with cloth, however, this would require resampling the surface at large planar deformations and the thickness of cloth would be bound to the particle size. This problem is addressed in this thesis by presenting a two-way coupling technique for cloth and fluids based on the simulation mesh of the textile. It allows robust contact handling and intuitive control of boundary conditions. Further, a solution for intersection-free fluid surface reconstruction at contact with thin flexible objects is presented. The visual quality of particle-based fluid animation highly depends on the properties of the reconstructed surface. An important aspect of the reconstruction method is that it accurately represents the underlying simulation. This thesis presents an evaluation of surfaces at interfaces of SPH simulations incorporating the connection to the simulation model. A typical approach in computer graphics is compared to surface reconstruction used in material sciences. The behavior of free surfaces in fluid animations is highly influenced by surface tension. This thesis presents an evaluation of three types of surface tension models in combination with different pressure force models for SPH to identify the individual characteristics of these models. Systematic tests using a set of benchmark scenes are performed to reveal strengths and weaknesses, and possible areas of applications.Physikalisch basierte Animationen sind ein allgegenwärtiger Teil in jeglichen Anwendungsbereichen der Computeranimation, insbesondere dem Unterhaltungssektor. Animations- und Spielfilme, Videospiele und Werbung enthalten visuelle Effekte unter Verwendung von physikalisch basierter Simulation, die sich nahtlos in Animations- oder Realfilme einfügen. Bei der Simulation von deformierbaren Materialien und Fluiden, insbesondere Flüssigkeiten, werden die Objekte gewöhnlich durch animierte Oberflächen dargestellt. Die visuelle Qualität dieser Oberflächen hängt nicht nur von den Eigenschaften der Fläche selbst ab, sondern auch von deren Erstellung und der Verbindung zu der zugrundeliegenden Simulation. Diese Dissertation widmet sich Oberflächen von Textil- und Fluidsimulationen mit der Methode der Smoothed Particle Hydrodynamics (SPH) und leistet einen Beitrag zur Verbesserung der Erstellung von Animationen durch die Beschreibung von Oberflächenformen, der Modellierung von Kontakt von Oberflächen und der Evaluierung von Oberflächeneffekten von Fluiden. In vielen Anwendungen gibt es eine Referenz für eine Oberflächenanimation, die ihre Form beschreibt. Das Abgleichen einer Referenz mit einer Simulation ist eine große Herausforderung und die Ähnlichkeit wird häufig visuell überprüft. Im ersten Teil der Dissertation wird eine Signatur für Textilanimationen vorgestellt, die charakteristische Formen und ihre zeitliche Veränderung erfasst. Sie ist eine Kombination aus geometrischen Merkmalen und physikalischen Eigenschaften, um das typische Deformationsverhalten genau zu repräsentieren. Die Signatur erlaubt es, Ähnlichkeiten zwischen Animationen zu berechnen, und wird angewendet, um Textilanimationen aus Kollektionen anhand eines Beispiels aufzufinden. Interaktionen zwischen partikelbasierten Fluiden und deformierbaren Objekten werden gewöhnlich durch das Abtasten des deformierbaren Objekts mit Partikeln modelliert. Bei der Interaktion mit Textilien würde dies jedoch ein neues Abtasten bei großen planaren Deformation erfordern und die Stärke des Textils wäre an die Partikelgröße gebunden. Mit diesem Problem befasst sich diese Dissertation und stellt eine Technik für die wechselseitige Kopplung zwischen Textilien und Fluiden vor, die auf dem Simulationsnetz des Textils beruht. Diese erlaubt eine robuste Kontaktbehandlung und intuitive Kontrolle von Randbedingungen. Des Weiteren wird ein Lösungsansatz für eine durchdringungsfreie Oberflächenrekonstruktion beim Kontakt mit dünnen flexiblen Objekten präsentiert. Die visuelle Qualität von partikelbasierten Fluidanimationen hängt stark von den Eigenschaften der rekonstruierten Oberfläche ab. Wichtig bei Rekonstruktionsmethoden ist, dass sie die zugrundeliegende Simulation genau repräsentieren. Die Dissertation präsentiert eine Evaluierung von Oberflächen an Grenzflächen, die den Zusammenhang zum Simulationsmodell miteinbezieht. Ein typischer Ansatz aus der Computergrafik wird mit der Oberflächenrekonstruktion in der Werkstoffkunde verglichen. Das Verhalten von freien Oberflächen in Fluidanimationen wird stark von der Oberflächenspannung beeinflusst. In dieser Dissertation wird eine Evaluierung von drei Oberflächenspannungsmodellen in Kombination mit verschiedenen Druckmodellen für SPH präsentiert, um die Charakteristika der jeweiligen Modelle zu identifizieren. Es werden systematische Tests mit Hilfe von Benchmark-Tests durchgeführt, um Stärken, Schwächen und mögliche Anwendungsbereiche deutlich zu machen

Desarrollo de un modelo avanzado de cálculo acoplado para el análisis del comportamiento en la mar de aerogeneradores flotantes

This thesis covers the implementation of a new tool to solve fluid problems capable of solving free-surface and fluid-solid interfaces. This tool is based on a Semi-Lagrangian Particle Finite Element Method (SL-PFEM) approach of solve the Navier-Stokes equations. In a similar fashion to the Particle Finite Element Method (PFEM) and its second generation version (PFEM-2), Lagrangian particles are used to solve the convection problem while a background mesh is used to solve the elliptic part of the Navier-Stokes equations. One of the objectives is that the tool must be efficient when calculating problems. This is managed by first developing the numerical scheme so that it is second order accurate in time and space and then optimising the implementation so that it can perform well in HPC environments. To solve the general interface problems such as fluid-fluid, fluid-solid or the two combined, then an enrichment method is applied to the scheme. This, joined with an SL-PFEM variation of the Level-Set Method allows to accurately capture and compute these types of problems. This implementation leads to the ability to solve multi-body problems that can interact with multiple fluids.Esta tesis trata sobre la implementación de una nueva herramienta para resolver problemas fluidodinámicos tratando, en particular, los problemas de interfaces fluido-fluido y sólido-fluido. Esta herramienta está basada en el "Semi-Lagrangian Particle Finite Element Method" (SL-PFEM) para resolver las ecuaciones de Navier-Stokes. De manera similar al "Particle Finite Element Method" (PFEM) y su segunda versión (PFEM-2), partículas Lagrangianas son usadas para resolver el problema de convección mientras que una malla fija se usa para resolver la parte elíptica de las ecuaciones de Navier-Stokes. Uno de los objetivos es que la herramienta debe ser capaz de resolver los problemas de manera eficiente. Para ello, primero se desarrolla el esquema numérico para que sea un esquema de segundo orden tanto en espacio y tiempo y, luego, se optimiza la implementación para obtener un buen rendimiento en entornos de supercomputación. Para resolver problemas de interfaces como los de fluido-fluido, solido-fluido o la combinación de ambas, un método de enriquecimiento es aplicado al esquema numérico. Esto, junto con una variación del método "Level-Set" aplicado al SL-PFEM permite capturar y calcular de forma precisa estos tipos de problemas. Además, esta implementación lleva a la capacidad de resolver problemas con más de un cuerpo que puedan interactuar con varios fluidos.Postprint (published version

Gurus and Media: Sound, image, machine, text and the digital

Gurus and Media is the first book dedicated to media and mediation in domains of public guruship and devotion. Illuminating the mediatisation of guruship and the guru-isation of media, it bridges the gap between scholarship on gurus and the disciplines of media and visual culture studies. It investigates guru iconographies in and across various time periods and also the distinctive ways in which diverse gurus engage with and inhabit different forms of media: statuary, games, print publications, photographs, portraiture, films, machines, social media, bodies, words, graffiti, dolls, sound, verse, tombs and more. The book’s interdisciplinary chapters advance, both conceptually and ethnographically, our understanding of the function of media in the dramatic production of guruship, and reflect on the corporate branding of gurus and on mediated guruship as a series of aesthetic traps for the captivation of devotees and others. They show how different media can further enliven the complex plurality of guruship, for instance in instantiating notions of ‘absent-present’ guruship and demonstrating the mutual mediation of gurus, caste and Hindutva. Throughout, the book foregrounds contested visions of the guru in the development of devotional publics and pluriform guruship across time and space. Thinking through the guru’s many media entanglements in a single place, the book contributes new insights to the study of South Asian religions and to the study of mediation more broadly

The use of computer-aided drug design in small molecule drug discovery

Drug discovery is one of the most challenging research fields that contributes to the birth of novel drugs for therapeutic use. Due to the complexity and intricate nature of the research, lengthy processes are involved in identifying potential hit molecules for a therapeutic target. To shorten the time required to reach the hit-to-lead stage, computer-aided drug design (CADD) has been used to expedite the process and reduce laboratory expenses. Common strategies used within CADD involve structure-based drug design (SBDD) and ligand-based drug design (LBDD). Both strategies were used extensively in two projects showing the complementarity of each strategy throughout the process. In this work, two separate drug discovery projects are detailed: Design, synthesis and molecular docking study of novel tetrahydrocurcumin analogues as potential sarcoplasmic-endoplasmic reticulum calcium ATPases (SERCA) inhibitors – details the identification, synthesis and testing of potential hit candidate(s) targeting SERCA by using SBDD Filamenting temperature-sensitive mutant Z (FtsZ) as therapeutic target in ligand-based drug design – details the identification, synthesis and testing of potential hit molecule(s) targeting FtsZ In the first project, homology modelling and virtual compound library screening were utilised as the SBDD methods to identify potential hit molecules for testing in P-type calcium ATPases such as SERCA. Preliminary results have found compound 20, an analogue of tetrahydrocurcumin, to show some SERCA inhibitory effect at 300µM based on a SERCA-specific calcium signalling assay performed via fluorometric imaging plate reader. Molecular docking study has also reflected this outcome with desirable ligand-protein binding energies found for 20 when compared with other tested ligands. Pharmacophore screening was used as the main LBDD method in the second project to identify probable hit candidates targeting FtsZ. Potential ligands were synthesised, and tested for antibacterial effect in Bacillus Subtilis strain 168 (Bs168) and Streptococcus pneumoniae strain R6 (SpnR6) cells. One of the tetrahydrocurcumin analogues, compound 4, was found to have minimum inhibitory concentration (MIC) ≤ 10 µM in Bs168 cells and ≤ 2 µM in spnR6 cells. The IC50 values for 4 were 9.1 ± 0.01 µM and 1 ± 0.01 µM in Bs168 and SpnR6 cells respectively. The MIC of 4 was found to be very similar to the MIC of compound 1, a known hit compound targeting against Bs168 cells. On the other hand, the MIC of 4 was lower than the MIC (> 64 µg/mL) of a well-known FtsZ inhibitor, PC190723, against S. pneumoniae. Subsequent molecular docking analyses were completed to evaluate the ligand-protein binding energies to correlate against the testing results. Both compounds 20 and 4 possess some structural similarities and differences that may confer their different effects in these protein targets, which render both with potentials to become the next lead molecules for future development

GVSU Press Releases, 2010

A compilation of press releases for the year 2010 submitted by University Communications (formerly News & Information Services) to news agencies concerning the people, places, and events related to Grand Valley State University