Animating ultra-complex voxel scenes through shell deformation

version draft du mémoireInternational audienceVoxel representations have many advantages, such as ordered traversal during rendering and trivial very decent LOD through MIPmap. Special effect companies such Digital Domain or Rhythm&Hues now ex- tensively use voxels engines, for semi-transparent objects such as clouds, avalanches, tornado or explosions, but also for complex solid objects. Several gaming companies are also looking into voxel engines to deal with ever more complex scenes but the main problem when dealing with voxel representations is the amount of data that has to be manipulated. This amount usually prevents animating in real time. To solve these is- sues, ARTIS team developed the Gigavoxels framework: a very powerful voxel engine based on GPU ray-casting, with advanced memory man- agement, so that very complex scenes can be rendered in real-time. The purpose of the TER was to develop a solution for animating voxel objects in real-time, implement it and eventually integrate it to the Gigavoxels framework

Real-Time deep image rendering and order independent transparency

In computer graphics some operations can be performed in either object space or image space. Image space computation can be advantageous, especially with the high parallelism of GPUs, improving speed, accuracy and ease of implementation. For many image space techniques the information contained in regular 2D images is limiting. Recent graphics hardware features, namely atomic operations and dynamic memory location writes, now make it possible to capture and store all per-pixel fragment data from the rasterizer in a single pass in what we call a deep image. A deep image provides a state where all fragments are available and gives a more complete image based geometry representation, providing new possibilities in image based rendering techniques. This thesis investigates deep images and their growing use in real-time image space applications. A focus is new techniques for improving fundamental operation performance, including construction, storage, fast fragment sorting and sampling. A core and driving application is order-independent transparency (OIT). A number of deep image sorting improvements are presented, through which an order of magnitude performance increase is achieved, significantly advancing the ability to perform transparency rendering in real time. In the broader context of image based rendering we look at deep images as a discretized 3D geometry representation and discuss sampling techniques for raycasting and antialiasing with an implicit fragment connectivity approach. Using these ideas a more computationally complex application is investigated — image based depth of field (DoF). Deep images are used to provide partial occlusion, and in particular a form of deep image mipmapping allows a fast approximate defocus blur of up to full screen size

HA-Buffer: Coherent Hashing for single-pass A-buffer

Identifying all the surfaces projecting into a pixel has several important applications in Computer Graphics, such as transparency and CSG. These applications further require ordering, in each pixel, the surfaces by their distance to the viewer. In real-time rendering engines, this is often achieved by recording sorted lists of the fragments produced by the rasterization pipeline. The major challenge is that the number of fragments is not known in advance. This results in computational and memory overheads due to the necessary dynamic nature of the data-structure. Similarly, many fragments which are not useful for the final image--due to opacity accumulation for instance--have to be stored and sorted nonetheless, negatively impacting performance. This paper proposes a novel approach which records and simultaneously sorts all fragments in a single geometry pass. The storage overhead per fragment is typically lower than 8 bits per record, and no pointers are involved. Since fragments are progressively sorted in memory, it is possible to assess during rendering whether a new fragment is useful. Our approach combines advantages of previous approaches at similar levels of performance, and is implemented in a single fragment shader of 24 lines of GLSL.Plusieurs applications en synthèse d'image nécessitent le calcul de l'ensemble des surfaces visibles au travers d'un pixel. Citons le dessin correct de surfaces transparentes ainsi que le dessin de mod'eles CSG. Ces applications nécessite également de trier les surfaces, pour chaque pixel, selon leur distance au point de vue. Pour les applications en temps-réel, ce sont les fragments produits par l'étape de rasterisation qui sont triés et stockés en mémoire vidéo. Le nombre de ces fragments n'étant pas connu à l'avance, il est nécessaire d'utiliser de coûteuses techniques de gestion de la mémoire. De plus, tous les fragments sont traités même si une fraction non négligeable d'entre eux peut être inutile au dessin de l'image finale (grâce, par exemple, à l'accumulation de l'opacité de plusieurs surfaces combinées). Nous proposons une technique simple pour trier les fragments d'un même pixel au moment de leur rasterisation, sans utiliser de liste chainée (et donc de pointeur). Puisque la liste des fragments pour un pixel est toujours triée, il est possible de déterminer, au moment de sa rasterisation, si un fragment contribuera ou pas à l'image finale, et de le rejetter le cas échéant. La technique combine les avantages de plusieurs approches existantes pour un niveau de performance similaire. Elle a l'unique avantage d'étre très simple à coder : 24 lignes de GLSL

Realistic hair rendering in Autodesk Maya

Tato diplomová práce popisuje real-time zobrazovaní vlasů v 3D modelovacím programu Autodesk Maya. Zobrazovací modul je součást projektu Stubble - zasuvného modulu do programu Maya, který slouží k modelovaní vlasů. Prezentovaný algoritmus poskytuje vysoce kvalitní interaktivní náhled, pomocí kterého je možné modelovat vlasy bez nutnosti zdlouhavého vytváření náhledu v externím programu. Cílem je vytvořit takový náhled, který se bude co nejvíce podobat obrázkům, které produkuje 3Delight - zasuvný modul pro program Maya, který implementuje standardy zobrazovacího rozhraní RenderMan.This thesis describes a real-time hair rendering in 3D animation and modeling software Autodesk Maya. The renderer is part of the Stubble project a - Maya plug-in for hair modeling. The presented renderer provides a high-quality interactive preview that allows fast hair modeling without the need for rendering in slow off-line renderers. The goal of this work is to create a renderer that can generate images in real-time that are as close as possible to the output of the 3Delight renderer - a plug-in for Maya that is based on RenderMan standards.Department of Software and Computer Science EducationKatedra softwaru a výuky informatikyFaculty of Mathematics and PhysicsMatematicko-fyzikální fakult

Using per-pixel linked lists for transparency effects in remote-rendering

Modern graphic cards are highly versatile because they allow the programmer to load custom code to execute onto them. This can be used to construct a structure called a per-pixel linked list, which contains all fragments composing the scene. However, with the need to render more and more complex geometry, even the most powerful hardware reaches its limit fast. To overcome this problem, the geometry is rendered on multiple systems instead of one, and finally put together for rendering. This is called remote rendering and works well for opaque scenes. The goal of this thesis is to conquer rendering of transparent objects remotely using per-pixel linked lists. Since rendering those objects requires a step called blending, standard approaches are incapable of displaying them. Three different methods are shown, compared and analyzed for their usability and performance. First, limiting the amount of depth layers is discussed. Second, identifying regions of visual change is used to reduce the amount of data to be sent. Finally, a way for reusing the previously sent fragments for the current frame is studied in detail.Moderne Grafikkarten sind sehr flexibel aufgrund ihrer Fähigkeit, vom Programmierer verfassten Code auszuführen. Dies kann dazu genutzt werden, eine Datenstruktur names Per-Pixel Linked List zu erstellen. Diese enthält alle Fragmente der zu rendernden Szene. Da aber aufgrund der immer komplexer werdenden Geometrie die Anforderungen stark steigen, erreichen selbst leistungsfähige Grafikkarten schnell ihre Grenzen. Um dieses Problem zu lösen bietet sich das sogenannte Remote Rendering an, bei welchem die Rechenlast auf mehrere Computer im Netzwerk verteilt und am Ende die einzelnen Zwischenbilder zu einem Gesamtbild vereint werden. Für opake Szenen gibt es bereits funktionierende Lösungen. Das Ziel dieser Arbeit ist die Behandlung transparenter Geometrie im Kontext des Remote Renderings mit Hilfe von Per-Pixel Linked Lists. Da das Rendern transparenter Objekte eine Operation namens Blending erfordert, sind die bisherigen Algorithmen meist nicht geeignet. Es werden drei verschiedene Methoden vorgestellt, analysiert und ihre Brauchbarkeit und Geschwindigkeit verglichen. Als erstes wird ein Verfahren, welches die Anzahl an Tiefenebenen limitiert, beleuchtet. Das zweite Verfahren versucht anhand optischer Differenzen zwischen dem aktuellen und dem vorausgegangenen Bild diejenigen Bereiche zu ermitteln, welche für ein korrektes Endbild übertragen werden müssen. Als letzte Technik wird ein Ansatz vorgestellt, welcher die Verwendung von bereits übertragener Fragmente dazu benutzt, um Fragmente einzusparen indem diese wiederverwendet werden

Mass Spectrometry in the Elucidation of the Glycoproteome of Bacterial Pathogens

Presently some three hundred post-translational modifications are known to occur in bacteria in vivo. Many of these modifications play critical roles in the regulation of proteins and control key biological processes. One of the most predominant modifications, N- and O-glycosylations are now known to be present in bacteria (and archaea) although they were long believed to be limited to eukaryotes. In a number of human pathogens these glycans have been found attached to the surfaces of pilin, flagellin and other surface and secreted proteins where it has been demonstrated that they play a role in the virulence of these bacteria. Mass spectrometry characterization of these glycosylation events has been the enabling key technology for these findings. This review will look at the use of mass spectrometry as a key technology for the detection and mapping of these modifications within microorganisms, with particular reference to the human pathogens, Campylobacter jejuni and Mycobacterium tuberculosis. The overall aim of this review will be to give a basic understanding of the current ‘state-of-the-art’ of the key techniques, principles and technologies, including bioinformatics tools, involved in the analysis of the glycosylation modifications

Visualização de conjuntos de dados grandes formados por esferas

Dissertação (mestrado) - Universidade Federal de Santa Catarina, Centro Tecnológico, Programa de Pós-Graduação em Ciência da Computação, Florianópolis, 2012Este trabalho trata da visualização grá?ca de conjuntos de dados cujas principais características é ser formado por esferas e possuir um grande volume de informações. As principais di?culdades em se trabalhar com dados numerosos é, além da performance, exibir a informação de forma clara. Para solucionar estes problemas foi criado um renderizador básico baseado na técnica de sprites com otimizações em nível de objeto e de imagem. Posteriormente foram analisados algoritmos de renderização com suporte a transparência, onde o depth peeling se mostrou adequado. O algoritmo foi adaptado para permitir a geração de uma imagem incompleta, tendo em vista a performance, porém foi feita uma quanti?cação do erro para limites aceitáveis poderem ser estabelecidos. Finalmente a modalidade de renderização utilizando a técnica de ambient occlusion foi implementada para melhor compreensão espacial dos dados, usando otimização de deferred shading. A performance obtida foi su?ciente para a visualização interativa dos conjuntos de dados.Abstract : This work deals with the graphical visualization of datasets which the main feature is being formed by spheres e have a great volume of information. The main dificulties when working with numerous data is, in addition to performance, show the information in a clear way. In order to solve these problems a basic renderer was created based on sprites techniques with optimizations at object and image level. Afterwards rendering algorithms with translucency support were analyzed, where depth peeling shown itself adequate. The algorithm was adapted to allow the generation of an incomplete image, in view of performance, but a quantification of the error was created so acceptable thresholds can be established. Finally the rendering mode using the ambient occlusion technique was implemented for better spatial comprehension of the data, using deferred shading optimization. The performance was enough for a interactive visualization of the datasets