Critters in the Classroom: A 3D Computer-Game-Like Tool for Teaching Programming to Computer Animation Students

The brewing crisis threatening computer science education is a well documented fact. To counter this and to increase enrolment and retention in computer science related degrees, it has been suggested to make programming "more fun" and to offer "multidisciplinary and cross-disciplinary programs" [Carter 2006]. The Computer Visualisation and Animation undergraduate degree at the National Centre for Computer Animation (Bournemouth University) is such a programme. Computer programming forms an integral part of the curriculum of this technical arts degree, and as educators we constantly face the challenge of having to encourage our students to engage with the subject. We intend to address this with our C-Sheep system, a reimagination of the "Karel the Robot" teaching tool [Pattis 1981], using modern 3D computer game graphics that today's students are familiar with. This provides a game-like setting for writing computer programs, using a task-specific set of instructions which allow users to take control of virtual entities acting within a micro world, effectively providing a graphical representation of the algorithms used. Whereas two decades ago, students would be intrigued by a 2D top-down representation of the micro world, the lack of the visual gimmickry found in modern computer games for representing the virtual world now makes it extremely difficult to maintain the interest of students from today's "Plug&Play generation". It is therefore especially important to aim for a 3D game-like representation which is "attractive and highly motivating to today's generation of media-conscious students" [Moskal et al. 2004]. Our system uses a modern, platform independent games engine, capable of presenting a visually rich virtual environment using a state of the art rendering engine of a type usually found in entertainment systems. Our aim is to entice students to spend more time programming, by providing them with an enjoyable experience. This paper provides a discussion of the 3D computer game technology employed in our system and presents examples of how this can be exploited to provide engaging exercises to create a rewarding learning experience for our students

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

Enhancing the Visualization of Percussion Gestures by Virtual Character Animation

International audienceA new interface for visualizing and analyzing percussion gestures is presented, proposing enhancements of existing motion capture analysis tools. This is achieved by offering a percussion gesture analysis protocol using motion capture. A virtual character dynamic model is then designed in order to take advantage of gesture characteristics, yielding to improve gesture analysis with visualization and interaction cues of different types

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

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

Art Directable Tornadoes

Tornado simulations in the visual effects industry have always been an interesting problem. Developing tools to provide more control over such effects is an important and challenging task. Current methods to achieve these effects use either particle systems or fluid simulation. Particle systems give a lot of control over the simulation but do not take into account the fluid characteristics of tornadoes. The other method which involves fluid simulation models the fluid behavior accurately but does not give control over the simulation. In this thesis, a novel method to model tornado behavior is presented. A tool based on this method was also created. The method proposed in this thesis uses a hybrid approach that combines the flexibility of particle systems while producing interesting swirling motions inherent in the fluids. The main focus of the research is on providing easy-to-use controls for art directors to help them achieve the desired look of the simulation effectively. A variety of controls is provided which include the overall shape, path, rotation, debris, surface, swirling motion, and interaction with the environment. The implementation was done in Houdini, which is a 3D animation software whose node based system allows an algorithmic approach to the problem and integrates well with the current tools. The tool allows the user to create animations that reflect the visual characteristics of real tornadoes. The usefulness of the tool was evaluated among participants who had some experience in 3D animation software. The results from the simulation and evaluation feedback reveal that the tool successfully allowed the users to create tornadoes of their choice efficiently

Real-time Realistic Rain Rendering

Artistic outdoor filming and rendering need to choose specific weather conditions in order to properly trigger the audience reaction; for instance, rain, one of the most common conditions, is usually employed to transmit a sense of unrest. Synthetic methods to recreate weather are an important avenue to simplify and cheapen filming, but simulations are a challenging problem due to the variety of different phenomena that need to be computed. Rain alone involves raindrops, splashes on the ground, fog, clouds, lightnings, etc. We propose a new rain rendering algorithm that uses and extends present state of the art approaches in this field. The scope of our method is to achieve real-time renders of rain streaks and splashes on the ground, while considering complex illumination effects and allowing an artistic direction for the drops placement. Our algorithm takes as input an artist-defined rain distribution and density, and then creates particles in the scene following these indications. No restrictions are imposed on the dimensions of the rain area, thus direct rendering approaches could rapidly overwhelm current computational capabilities with huge particle amounts. To solve this situation, we propose techniques that, in rendering time, adaptively sample the particles generated in order to only select the ones in the regions that really need to be simulated and rendered. Particle simulation is executed entirely in the graphics hardware. The algorithm proceeds by placing the particles in their updated coordinates. It then checks whether a particle is falling as a rain streak, it has reached the ground and it is a splash or, finally, if it should be discarded because it has entered a solid object of the scene. Different rendering techniques are used for each case. Complex illumination parameters are computed for rain streaks to select textures matching them. These textures are generated in a preprocess step and realistically simulate light when interacting with the optical properties of the water drops

Modeling dendritic shapes - using path planning

Dendritic shapes are commonplace in the natural world such as trees, lichens, coral and lightning. Models of dendritic shapes are widely needed in many areas. Because of their branching fractal and erratic structures modeling dendritic shapes is a tricky task. Existing methods for modeling dendritic shapes are slow and complicated.In this thesis we present a procedural algorithm of using path planning to model dendritic shapes. We generate a dendrite by finding the least-cost paths from multiple endpoints to a common generator and use the dendrite to build the geometric model. With the control handles of endpoint placement, fractal shape, edge weights distribution and path width, we create different shapes of dendrites that simulate different kinds of dendritic shapes very well. Compared with some existing methods, our algorithm is fast and simple