Exploring mesh shaders

Dissertação de mestrado integrado em Engenharia InformáticaEvery artist is somewhat limited by the mean by which they expose their art. This is also true for the field of Computer Graphics, where there are many limiting factors that developers must go out of their way to avoid. The most limiting of these factors is the computing performance, which directly limits the complexity of what an artist can fabricate in a piece of hardware. As such, Computer Graphics’ investigators keep an eye out for the improvements made in the hardware department that enables them to introduce more complexity to the scenes they create on their computers. Three years ago, a novel approach to compute the geometric complexity of three-dimensional (3D) scenes was introduced: Mesh shaders. Mesh shaders pose as an alternative to the traditional geometric processing method and can be a more performant approach to handle specific geometric workloads. Notwithstanding, little attention has been given to these shaders. Thus, this thesis presents an investigative effort to evaluate the value proposition of these shaders across different scenarios. To do so, this thesis puts Mesh shaders against traditional implementations and measures their differences both in method and performance. By the end of this thesis, the reader should have a concise understanding of Mesh shaders, but not a clear cut answer regarding their use. These shaders can provide performance benefits in specific scenarios over the traditional approach, but not without considerable care by the developer. In fact, the flexibility provided by the Mesh shaders’ approach gives the developer a significant responsibility regarding their final performance. When incorrectly set up, these shaders can result in mediocre performances compared to those of the traditional pipeline. Ultimately, these shaders should be used by experienced users intending to avoid specific bottlenecks of the traditional approach. For others, the traditional pipeline offers a more streamlined approach, thoroughly optimised by default.Todos os artistas são de alguma forma limitados pelo meio de exposição da sua arte. Isto não deixa de ser verdade com Computação Gráfica, onde existem vários fatores limitadores que os programadores têm de con tornar. Entre estes, o mais impeditivo é a velocidade de computação, que limita diretamente a complexidade da arte que pode ser produzida por uma peça de hardware. Deste modo, os investigadores da área de Computação Gráfica mantêm-se atentos às inovações que ocorrem no campo do hardware e lhes permitem introduzir mais complexidade nos cenários que criam. Há três anos, um método inédito para tratar a complexidade geométrica de cenas tridimensionais foi intro duzido: Mesh shaders. Os Mesh shaders apresentam-se como uma alternativa ao método tradicional de pro cessamento de geometria, que pode obter melhor desempenho em certos cenários geométricos. No entanto, não tem sido dada muita atenção a esta alternativa. Assim, esta tese apresenta uma investigação destes shaders com o intuito de avaliar a sua proposta de valor em diferentes situações. Para o fazer, esta tese irá colocar estes shaders frente a frente com os shaders tradicionais e medirá as diferenças entre ambos, tanto em desempenho como em método. No final, o leitor deverá possuir uma ideia coesa sobre os Mesh shaders, mas não terá uma perceção binária quanto ao uso dos mesmos. Isto porque estes shaders podem oferecer um benefício em termos de desempenho em certas situações, mas requerem cuidados adicionais por parte do programador. Da flexibilidade oferecida pelos Mesh shaders advém uma responsabilidade significativa para o programador no que toca ao desempenho final dos mesmos. Quando programados incorretamente, estes shaders resultarão num desempenho medíocre comparado ao desempenho oferecido pelo método tradicional. Fundamentalmente, estes shaders deverão ser utilizados por utilizadores mais experientes que pretendem evitar bottlenecks específicos do método tradicional. Para todos os outros, o pipeline tradicional oferece um método mais simples que possui por predefinição otimizações acentuadas

A survey of real-time crowd rendering

In this survey we review, classify and compare existing approaches for real-time crowd rendering. We first overview character animation techniques, as they are highly tied to crowd rendering performance, and then we analyze the state of the art in crowd rendering. We discuss different representations for level-of-detail (LoD) rendering of animated characters, including polygon-based, point-based, and image-based techniques, and review different criteria for runtime LoD selection. Besides LoD approaches, we review classic acceleration schemes, such as frustum culling and occlusion culling, and describe how they can be adapted to handle crowds of animated characters. We also discuss specific acceleration techniques for crowd rendering, such as primitive pseudo-instancing, palette skinning, and dynamic key-pose caching, which benefit from current graphics hardware. We also address other factors affecting performance and realism of crowds such as lighting, shadowing, clothing and variability. Finally we provide an exhaustive comparison of the most relevant approaches in the field.Peer ReviewedPostprint (author's final draft

Implementation of digital pheromones in PSO accelerated by commodity Graphics Hardware

In this paper, a model for Graphics Processing Unit (GPU) implementation of Particle Swarm Optimization (PSO) using digital pheromones to coordinate swarms within ndimensional design spaces is presented. Previous work by the authors demonstrated the capability of digital pheromones within PSO for searching n-dimensional design spaces with improved accuracy, efficiency and reliability in both serial and parallel computing environments using traditional CPUs. Modern GPUs have proven to outperform the number of floating point operations when compared to CPUs through inherent data parallel architecture and higher bandwidth capabilities. The advent of programmable graphics hardware in the recent times further provided a suitable platform for scientific computing particularly in the field of design optimization. However, the data parallel architecture of GPUs requires a specialized formulation for leveraging its computational capabilities. When the objective function computations are appropriately formulated for GPUs, it is theorized that the solution efficiency (speed) can be significantly increased while maintaining solution accuracy. The development of this method together with a number of multi-modal unconstrained test problems are tested and presented in this paper

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

A WebGL application based on BIM IFC

Dissertação apresentada à Universidade Fernando Pessoa como partes dos requisitos para a obtenção do grau de Mestre em Engenharia Informática, ramo de Computação MóvelThe possibility of displaying high performance 3D accelerated graphics in the browser is seen as an obstacle to the conversion of applications to the web. The release of WebGL made Web3D gain new strength to overcome that obstacle. Architecture, Engineering and Construction (AEC) tools are a type of applications that could benefit with this advance. In the AEC industry, there is a standard candidate for Building Information Modelling (BIM), called Industry Foundation Classes (IFC). This data model promotes interoperability between AEC tools, giving a common format to the applications. This work comes from the need of redesigning a legacy application that allows the user to design, display and calculate building structures. Focusing on the displaying of building structures, this work merges IFC and WebGL into an application, to replicate in a modern way the legacy application capabilities. This is done by developing a server module that processes the IFC data model and a client module that displays that model in a WebGL environment. The result is a prototype web application capable of displaying 3D IFC building models in the browser without plug-ins. A possibilidade de visualização de gráficos acelerados 3D de alto desempenho no navegador ainda é visto como um obstáculo na migração de aplicações para a web. O lançamento do WebGL fez o Web3D ganhar uma nova força para superar esse obstáculo. As ferramentas de Arquitetura, Engenharia e Construção (AEC) são um tipo de aplicações que podem beneficiar com este avanço. Na indústria AEC, há um candidato a padrão para Building Information Modelling (BIM), chamado de Industry Foundation Classes (IFC). Este modelo de dados promove a interoperabilidade entre as ferramentas de AEC, fornecendo um formato comum às aplicações. Este trabalho surge da necessidade de redesenhar uma aplicação legada que permite ao o utilizador projetar, visualizar e calcular estruturas de edifícios. Focando na visualização de estruturas de edifícios, este trabalho funde o IFC e o WebGL numa aplicação, para replicar de forma moderna as capacidades da aplicação legada. Isto é feito através do desenvolvimento de um módulo de servidor que processa o modelo de dados IFC e um módulo de cliente que mostra esse modelo num ambiente WebGL. O resultado é um protótipo duma aplicação web capaz de visualizar modelos 3D de edifícios em formato IFC no browser sem plug-ins

Interactive Video Game Content Authoring using Procedural Methods

This thesis explores avenues for improving the quality and detail of game graphics, in the context of constraints that are common to most game development studios. The research begins by identifying two dominant constraints; limitations in the capacity of target gaming hardware/platforms, and processes that hinder the productivity of game art/content creation. From these constraints, themes were derived which directed the research‟s focus. These include the use of algorithmic or „procedural‟ methods in the creation of graphics content for games, and the use of an „interactive‟ content creation strategy, to better facilitate artist production workflow. Interactive workflow represents an emerging paradigm shift in content creation processes used by the industry, which directly integrates game rendering technology into the content authoring process. The primary motivation for this is to provide „high frequency‟ visual feedback that enables artists to see games content in context, during the authoring process. By merging these themes, this research develops a production strategy that takes advantage of „high frequency feedback‟ in an interactive workflow, to directly expose procedural methods to artists‟, for use in the content creation process. Procedural methods have a characteristically small „memory footprint‟ and are capable of generating massive volumes of data. Their small „size to data volume‟ ratio makes them particularly well suited for use in game rendering situations, where capacity constraints are an issue. In addition, an interactive authoring environment is well suited to the task of setting parameters for procedural methods, reducing a major barrier to their acceptance by artists. An interactive content authoring environment was developed during this research. Two algorithms were designed and implemented. These algorithms provide artists‟ with abstract mechanisms which accelerate common game content development processes; namely object placement in game environments, and the delivery of variation between similar game objects. In keeping with the theme of this research, the core functionality of these algorithms is delivered via procedural methods. Through this, production overhead that is associated with these content development processes is essentially offloaded from artists onto the processing capability of modern gaming hardware. This research shows how procedurally based content authoring algorithms not only harmonize with the issues of hardware capacity constraints, but also make the authoring of larger and more detailed volumes of games content more feasible in the game production process. Algorithms and ideas developed during this research demonstrate the use of procedurally based, interactive content creation, towards improving detail and complexity in the graphics of games

3D modeling and visualization of utility networks

Most of the current 2D GIS representations are tied to the limits of the GIS software tools used and are, more properly, simplifications of the real aspects of the territory. The development of 3D GIS tools has brought to life by the belief that the description of the reality and the analysis of the phenomena that take place in it must be done in the proper dimensions. An important field of application of GIS software tools is the utility networks management. Existing software tools that support management and 3D visualisation of utility networks are powerful but very expansive. The aim of the project is to design a general network model that will be used to model an utility network and to visualise it in 3D. The general network model has been designed to be data source and platform independent. It can take data from OGC standard compliant data source like GeoDBMS and WFS Servers and can be enriched by a user defined set of attributes, making it suitable for every network analysis and management need. On the top of the general network model has been designed a geometrical model that transforms the general network model in a 3D model which can be displayed using a WebGL graphic engine. Using the general network model and the geometrical model has been designed and developed a WebGL viewer that visualises the network model over a DTM with a complete navigation system that allows a complete tour of the scene and data query and editingopenEmbargo per motivi di segretezza e di proprietà dei risultati e informazioni sensibil

Towards a High Quality Real-Time Graphics Pipeline

Modern graphics hardware pipelines create photorealistic images with high geometric complexity in real time. The quality is constantly improving and advanced techniques from feature film visual effects, such as high dynamic range images and support for higher-order surface primitives, have recently been adopted. Visual effect techniques have large computational costs and significant memory bandwidth usage. In this thesis, we identify three problem areas and propose new algorithms that increase the performance of a set of computer graphics techniques. Our main focus is on efficient algorithms for the real-time graphics pipeline, but parts of our research are equally applicable to offline rendering. Our first focus is texture compression, which is a technique to reduce the memory bandwidth usage. The core idea is to store images in small compressed blocks which are sent over the memory bus and are decompressed on-the-fly when accessed. We present compression algorithms for two types of texture formats. High dynamic range images capture environment lighting with luminance differences over a wide intensity range. Normal maps store perturbation vectors for local surface normals, and give the illusion of high geometric surface detail. Our compression formats are tailored to these texture types and have compression ratios of 6:1, high visual fidelity, and low-cost decompression logic. Our second focus is tessellation culling. Culling is a commonly used technique in computer graphics for removing work that does not contribute to the final image, such as completely hidden geometry. By discarding rendering primitives from further processing, substantial arithmetic computations and memory bandwidth can be saved. Modern graphics processing units include flexible tessellation stages, where rendering primitives are subdivided for increased geometric detail. Images with highly detailed models can be synthesized, but the incurred cost is significant. We have devised a simple remapping technique that allowsfor better tessellation distribution in screen space. Furthermore, we present programmable tessellation culling, where bounding volumes for displaced geometry are computed and used to conservatively test if a primitive can be discarded before tessellation. We introduce a general tessellation culling framework, and an optimized algorithm for rendering of displaced Bézier patches, which is expected to be a common use case for graphics hardware tessellation. Our third and final focus is forward-looking, and relates to efficient algorithms for stochastic rasterization, a rendering technique where camera effects such as depth of field and motion blur can be faithfully simulated. We extend a graphics pipeline with stochastic rasterization in spatio-temporal space and show that stochastic motion blur can be rendered with rather modest pipeline modifications. Furthermore, backface culling algorithms for motion blur and depth of field rendering are presented, which are directly applicable to stochastic rasterization. Hopefully, our work in this field brings us closer to high quality real-time stochastic rendering