774 research outputs found
Space colonization for the procedural generation of lightning
Dissertação de mestrado integrado em Engenharia InformáticaThe procedural generation of geometry within the space of computer graphics has been a topic of study for quite
some time, benefiting from a more unpredictable brand of randomness. Similarly, the exploration of lighting as a
phenomenon within virtual space has been a field of study of comparable age.
Despite its age and early adoption, there is a surprising lack of research in emulating the phenomenon of
lighting past its interactions with the world. Most implementations of procedurally generated lightning within video
games are based on randomized data trees. When part of the skybox, 2D meshes or textures are randomly
selected from a pre-made pool. There are, however, methods based entirely on the dielectric breakdown model,
using approximations to solve a Laplacian equation.
This dissertation aims to present an alternative approach to the randomized and procedural generation of
lightning bolts based on the Space Colonization algorithm. While the algorithm was first conceived for use in
botanical applications, modeling the growth of biological structures, the similarities between the results produced
by the dielectric breakdown model and botanic modeling algorithms coupled with the visual likeness of a lightning
bolt and certain trees, made for solid groundwork upon which to establish this unique approach.
As such, this work largely aims to be a first step into this particular realm, showing Space Colonization
as a suitable algorithm for this specific purpose. That being said, a large portion of time was spent iterating,
modifying and experimenting with ideas that were either discarded or adapted, an effort primarily dedicated
towards controlling and stifling the possible growth of branches in ways beyond the reduction of attractors.
The original algorithm was altered, focus put especially on the creation of a singular channel at a time, mixing
discoveries from previous research with the work done on manipulating Space Colonization. Instead of the
venation patterns observed with the original work, the stifling of any growth means that each node has a chance,
when created, of sprouting a branch and each branch is, in turn, a different, modified instance of the same
underlying concept providing an additional level of control. Effort was equally placed on showcasing different
properties inherent to a lightning strike, such as its iterative construction when descending from its origin.
In the rendering section, along with recreating the bloom and glow effect seen in previous works, effort was put
into recreating the strobing observed in capturing slow-motion footage of lightning bolts with special detail given
to this. In addition, parameters were joined with a waypoint system to allow for a great degree of freedom when
generating new bolts.A geração iterativa de geometria no contexto de computação gráfica é um tópico de estudo à já algum tempo
apesar de usado em apenas contextos específicos, um ramo que benefícia de um tipo de aleatoriedade
imprevisível. Similarmente, a exploração de relâmpagos como um fenómeno em espaço virtual é uma faceta de
idade comparável.
Apesar disto, o foco quando tratando relâmpagos tem caído marioritariamente nos seus efeitos após impacto.
Estudos têm sido conduzidos no âmbito de mitigar o dano causado por estes em fuselagem de aeronaves e
analizar o impacto de trovoada em estruturas críticas. No entanto, existe uma falta de investigação sobre a
emulação deste fenómeno barra as suas interações com o mundo. A maioria das implementações iterativas em
video jogos são baseadas em árvores de dados. Quando fazem parte do cenário, são marioritariamente meshes
ou texturas 2D selecionas aleatoriamente de um conjunto. Existem, no entanto, métodos baseados num modelo
de colapso elétrico usando apróximações a uma equação de Laplace.
Esta dissertação tem como foco apresentar uma alternativa para a geração aleatória e iterativa de relâmpagos
baseada no algoritmo de Space Colonization. Apesar deste algoritmo ter sido concebido para uso botânico,
modelando o crescimento de estruturas biológicas, as similaridades entre os resultados obtidos pelo modelo
de colapso elétrico e estes algoritmos de modelagem, quando considerados com a semelhança entre certos
relâmpagos e árvores, constroem uma fundação sólida para o tópico.
Neste âmbito, este trabalho é um primeiro passo que tem o intuito de mostrar a capacidade do algoritmo
de Space Colonization em simular relâmpagos. Dito isto, uma grande porção do tempo de desenvolvimento
dobrou-se sobre a iteração modificação e experimentação de ideias que foram discardadas ou adaptadas, um
esforço primariamente dedicado em controlar o crescimento de ramos sem reduzir o número de atratores.
O algoritmo original foi alterado, focando especialmente na criação de um único canal e fazendo uso de
conhecimento prévio, oriundo de trabalho e investigação feita sobre manipulação de Space Colonization. Em vez
de padrões de venação, observados no trabalho original, o impedimento de qualquer crescimento significa que
cada nodo tem uma probabilidade, quando criado, de dar origem a um ramo e que cada ramo é uma instância
diferente e modificada do mesmo conceito, algo que cria um nível de controlo mais profundo. Um esforço extra
foi, também, realizado com o intuito de mostrar todas as propriedades diferentes, inerentes a um relâmpago tal
como a construção iterativa durante a sua travessia.
Na parte de renderização, foram recriados efeitos de brilho e bloom vistos em trabalhos prévios. Foi também
dada especial atenção à recriação do efeito estroboscópico observado durante a análise de imagens em câmera
lenta, algo que se tornou no foco principal desta parte. Adicionalmente, a adição de parâmetros foi conjugada
com um sistema de pontos que dá um grau superior de liberdade ao utilizador
Volumetric intelligence: A framework for the creation of interactive volumetric captured characters
Virtual simulation of human faces and facial movements has challenged media artists and computer scientists since the first realistic 3D renderings of a human face by Fred Parke in 1972. Today, a range of software and techniques are available for modelling virtual characters and their facial behavior in immersive environments, such as computer games or storyworlds. However, applying these techniques often requires large teams with multidisciplinary expertise, extensive amount of manual labor, as well as financial conditions that are not typically available for individual media artists.
This thesis work demonstrates how an individual artist may create humanlike virtual characters – specifically their facial behavior – in a relatively fast and automated manner. The method is based on volumetric capturing, or photogrammetry, of a set of facial expressions from a real person using a multi-camera setup, and further applying open source and accessible 3D reconstruction and re-topology techniques and software. Furthermore, the study discusses possibilities of utilizing contemporary game engines and applications for building settings that allow real-time interaction between the user and virtual characters.
The thesis documents an innovative framework for the creation of a virtual character captured from a real person, that can be presented and driven in real-time, without the need of a specialized team, high budget or intensive manual labor. This workflow is suitable for research groups, independent teams and individuals seeking for the creation of immersive and real-time experiences and experiments using virtual humanlike characters
LiCROM: Linear-Subspace Continuous Reduced Order Modeling with Neural Fields
Linear reduced-order modeling (ROM) simplifies complex simulations by
approximating the behavior of a system using a simplified kinematic
representation. Typically, ROM is trained on input simulations created with a
specific spatial discretization, and then serves to accelerate simulations with
the same discretization. This discretization-dependence is restrictive.
Becoming independent of a specific discretization would provide flexibility
to mix and match mesh resolutions, connectivity, and type (tetrahedral,
hexahedral) in training data; to accelerate simulations with novel
discretizations unseen during training; and to accelerate adaptive simulations
that temporally or parametrically change the discretization.
We present a flexible, discretization-independent approach to reduced-order
modeling. Like traditional ROM, we represent the configuration as a linear
combination of displacement fields. Unlike traditional ROM, our displacement
fields are continuous maps from every point on the reference domain to a
corresponding displacement vector; these maps are represented as implicit
neural fields.
With linear continuous ROM (LiCROM), our training set can include multiple
geometries undergoing multiple loading conditions, independent of their
discretization. This opens the door to novel applications of reduced order
modeling. We can now accelerate simulations that modify the geometry at
runtime, for instance via cutting, hole punching, and even swapping the entire
mesh. We can also accelerate simulations of geometries unseen during training.
We demonstrate one-shot generalization, training on a single geometry and
subsequently simulating various unseen geometries
Photorealistic physically based render engines: a comparative study
Pérez Roig, F. (2012). Photorealistic physically based render engines: a comparative study. http://hdl.handle.net/10251/14797.Archivo delegad
Using simulation to calibrate real data acquisition in veterinary medicine
This paper explores the innovative use of simulation environments to enhance
data acquisition and diagnostics in veterinary medicine, focusing specifically
on gait analysis in dogs. The study harnesses the power of Blender and the
Blenderproc library to generate synthetic datasets that reflect diverse
anatomical, environmental, and behavioral conditions. The generated data,
represented in graph form and standardized for optimal analysis, is utilized to
train machine learning algorithms for identifying normal and abnormal gaits.
Two distinct datasets with varying degrees of camera angle granularity are
created to further investigate the influence of camera perspective on model
accuracy. Preliminary results suggest that this simulation-based approach holds
promise for advancing veterinary diagnostics by enabling more precise data
acquisition and more effective machine learning models. By integrating
synthetic and real-world patient data, the study lays a robust foundation for
improving overall effectiveness and efficiency in veterinary medicine
Simulation of a flowing snow avalanche using molecular dynamics
This paper presents an approach for the modeling and simulation of a flowing snow avalanche, which is formed of dry and liquefied snow that slides down a slope, using molecular dynamics and the discrete element method. A particle system is utilized as a base method for the simulation and marching cubes with real-time shaders are employed for rendering. A uniform grid-based neighbor search algorithm is used for collision detection for interparticle and particleterrain interactions. A mass-spring model of the collision resolution is employed to mimic the compressibility of the snow and particle attraction forces are put into use between the particles and terrain surface. In order to achieve greater performance, general purpose GPU language and multithreaded programming are utilized for collision detection and resolution. The results are displayed with different combinations of rendering methods for the realistic representation of the flowing avalanche. © TÜB̄TAK
The application of three-dimensional mass-spring structures in the real-time simulation of sheet materials for computer generated imagery
Despite the resources devoted to computer graphics technology over the last 40 years,
there is still a need to increase the realism with which flexible materials are simulated.
However, to date reported methods are restricted in their application by their use of
two-dimensional structures and implicit integration methods that lend themselves to
modelling cloth-like sheets but not stiffer, thicker materials in which bending moments
play a significant role.
This thesis presents a real-time, computationally efficient environment for simulations
of sheet materials. The approach described differs from other techniques principally
through its novel use of multilayer sheet structures. In addition to more accurately
modelling bending moment effects, it also allows the effects of increased temperature
within the environment to be simulated. Limitations of this approach include the
increased difficulties of calibrating a realistic and stable simulation compared to
implicit based methods.
A series of experiments are conducted to establish the effectiveness of the technique,
evaluating the suitability of different integration methods, sheet structures, and
simulation parameters, before conducting a Human Computer Interaction (HCI) based
evaluation to establish the effectiveness with which the technique can produce credible
simulations. These results are also compared against a system that utilises an
established method for sheet simulation and a hybrid solution that combines the use of
3D (i.e. multilayer) lattice structures with the recognised sheet simulation approach.
The results suggest that the use of a three-dimensional structure does provide a level of
enhanced realism when simulating stiff laminar materials although the best overall
results were achieved through the use of the hybrid model
Power Diagrams and Sparse Paged Grids for High Resolution Adaptive Liquids
© ACM, 2017. This is the author's version of the work. It is posted here by permission of ACM for your personal use. Not for redistribution. The definitive version was published in Aanjaneya, M., Gao, M., Liu, H., Batty, C., & Sifakis, E. (2017). Power Diagrams and Sparse Paged Grids for High Resolution Adaptive Liquids. ACM Trans. Graph., 36(4), 140:1–140:12. https://doi.org/10.1145/3072959.3073625We present an efficient and scalable octree-inspired fluid simulation framework with the flexibility to leverage adaptivity in any part of the computational domain, even when resolution transitions reach the free surface. Our methodology ensures symmetry, definiteness and second order accuracy of the discrete Poisson operator, and eliminates numerical and visual artifacts of prior octree schemes. This is achieved by adapting the operators acting on the octree's simulation variables to reflect the structure and connectivity of a power diagram, which recovers primal-dual mesh orthogonality and eliminates problematic T-junction configurations. We show how such operators can be efficiently implemented using a pyramid of sparsely populated uniform grids, enhancing the regularity of operations and facilitating parallelization. A novel scheme is proposed for encoding the topology of the power diagram in the neighborhood of each octree cell, allowing us to locally reconstruct it on the fly via a lookup table, rather than resorting to costly explicit meshing. The pressure Poisson equation is solved via a highly efficient, matrix-free multigrid preconditioner for Conjugate Gradient, adapted to the power diagram discretization. We use another sparsely populated uniform grid for high resolution interface tracking with a narrow band level set representation. Using the recently introduced SPGrid data structure, sparse uniform grids in both the power diagram discretization and our narrow band level set can be compactly stored and efficiently updated via streaming operations. Additionally, we present enhancements to adaptive level set advection, velocity extrapolation, and the fast marching method for redistancing. Our overall framework gracefully accommodates the task of dynamically adapting the octree topology during simulation. We demonstrate end-to-end simulations of complex adaptive flows in irregularly shaped domains, with tens of millions of degrees of freedom.National Science FoundationNational Sciences and Engineering Research Council of Canad
Output-Sensitive Rendering of Detailed Animated Characters for Crowd Simulation
High-quality, detailed animated characters are often represented as textured
polygonal meshes. The problem with this technique is the high cost
that involves rendering and animating each one of these characters. This
problem has become a major limiting factor in crowd simulation. Since we
want to render a huge number of characters in real-time, the purpose of
this thesis is therefore to study the current existing approaches in crowd
rendering to derive a novel approach.
The main limitations we have found when using impostors are (1) the
big amount of memory needed to store them, which also has to be sent
to the graphics card, (2) the lack of visual quality in close-up views, and
(3) some visibility problems. As we wanted to overcome these limitations,
and improve performance results, the found conclusions lead us to present
a new representation for 3D animated characters using relief mapping, thus
supporting an output-sensitive rendering.
The basic idea of our approach is to encode each character through a
small collection of textured boxes storing color and depth values. At runtime,
each box is animated according to the rigid transformation of its associated
bone in the animated skeleton. A fragment shader is used to recover
the original geometry using an adapted version of relief mapping. Unlike
competing output-sensitive approaches, our compact representation is able
to recover high-frequency surface details and reproduces view-motion parallax
e ects. Furthermore, the proposed approach ensures correct visibility
among di erent animated parts, and it does not require us to prede ne the
animation sequences nor to select a subset of discrete views. Finally, a user
study demonstrates that our approach allows for a large number of simulated
agents with negligible visual artifacts
Crystalline
Crystalline is a fast action arena shooter with a focus on gunplay. The core objective of this project was to create a fun multiplayer First Person Shooter. To achieve this goal as a team we had to best leverage the tools and technology available to us. As First Person Shooter games typically have teams far larger than our own, we had to work hard and smart on Crystalline. Unreal Engine 4 was used in lieu of Unity or an in-house engine, saving hours of development time and allowing us to focus on gameplay and assets more. Thanks to Unreal Engine 4, we were able to produce a game that, based on playtesting, appears to meet our core objective. Due to the limited time available for the project, there are still far more designed features to be implemented. However, the core gameplay has been completed leaving opportunity for expansion and future work. This document is divided into nine chapters and an appendix. Chapter 1 will introduce readers to the core concepts of Crystalline. Market analysis and background research are covered in Chapters 2 and 3 respectively. The prototypes and general process that took Crystalline from concept to game are outlined in Chapter 4. Chapters 5 and 6 outline the core design of the final iteration of Crystalline, technical or otherwise. Chapter 7 describes overall visual designs of the game, both 2D and 3D. Playtesting data is reported and assessed in Chapter 8, and a post mortem is detailed in Chapter 9. This document concludes with an appendix containing an asset bible
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