The Comparison of three 3D graphics raster processors and the design of another

There are a number of 3D graphics accelerator architectures on the market today. One of the largest issues concerning the design of a 3D accelerator is that of affordability for the home user while still delivering good performance. Three such architectures were analyzed: the Heresy architecture defined by Chiueh [2], the Talisman architecture defined by Torborg [7], and the Tayra architecture\u27s specification by White [9]. Portions of these three architectures were used to create a new architecture taking advantage of as many of their features as possible. The advantage of chunking will be analyzed, along with the advantages of a single cycle z-buffering algorithm. It was found that Fast Phong Shading is not suitable for implementation in this pipeline, and that the clipping algorithm should be eliminated in favor of a scissoring algorithm

Texture mapping with ray tracing

Includes bibliographical references leaves 56-59.Thesis (Master's)--Bilkent University, 1993.Ankara : The Department of Computer Engineering and Information Science and Institute of Engineering and Science of Bilkent University,1993.By using texture generation and global illumination techniques, it is possible to produce realistic computer images. Currently, ray tracing is one of the most popular global illumination techniques due to its simplicity, elegance, and easy implementation. In this thesis, texture mapping techniques are used with ray tracing to generate high quality visual effects. The implementation of the mapping process is presented and an approach for combining prefiltering techniques with ray tracing is introduced. General sweep surfaces produced by Topologybook are used for modeling.by Uğur Akdemir.M.S

Texture mapping on geometrical models

Ankara : The Department of Computer Engineering and Information Sciences and the Institute of Engineering and Science of Bilkent Univ. , 1989.Thesis (Master's) -- Bilkent University, 1989Includes bibliographical references leaves 37-39.The contribution of the visual effects of textures is an important aspect in generating images of real objects. Texture mapping is a very successful technique in this respect. Texture mapping can be subdivided into two fundamental topics; the geometric mapping and the filtering. The texture mapping system developed in this study is adaptable to different types of geometric models. Superqueadric, Bezier or b-spline surfaces can be mapped with textures. The geometric modeling and the texture synthesis subsystems were also implemented for this purpose. The system works in an interactive manner, the user describes the geometric model and the texture and gets the result in a reasonable amount of time. The speed and the usability of the system by a naive user are the keypoints of implementation.Açıkgöz, Oktay AydınM.S

A Method of Rendering CSG-Type Solids Using a Hybrid of Conventional Rendering Methods and Ray Tracing Techniques

This thesis describes a fast, efficient and innovative algorithm for producing shaded, still images of complex objects, built using constructive solid geometry ( CSG ) techniques. The algorithm uses a hybrid of conventional rendering methods and ray tracing techniques. A description of existing modelling and rendering methods is given in chapters 1, 2 and 3, with emphasis on the data structures and rendering techniques selected for incorporation in the hybrid method. Chapter 4 gives a general description of the hybrid method. This method processes data in the screen coordinate system and generates images in scan-line order. Scan lines are divided into spans (or segments) using the bounding rectangles of primitives calculated in screen coordinates. Conventional rendering methods and ray tracing techniques are used interchangeably along each scan-line. The method used is detennined by the number of primitives associated with a particular span. Conventional rendering methods are used when only one primitive is associated with a span, ray tracing techniques are used for hidden surface removal when two or more primitives are involved. In the latter case each pixel in the span is evaluated by accessing the polygon that is visible within each primitive associated with the span. The depth values (i. e. z-coordinates derived from the 3-dimensional definition) of the polygons involved are deduced for the pixel's position using linear interpolation. These values are used to determine the visible polygon. The CSG tree is accessed from the bottom upwards via an ordered index that enables the 'visible' primitives on any particular scan-line to be efficiently located. Within each primitive an ordered path through the data structure provides the polygons potentially visible on a particular scan-line. Lists of the active primitives and paths to potentially visible polygons are maintained throughout the rendering step and enable span coherence and scan-line coherence to be fully utilised. The results of tests with a range of typical objects and scenes are provided in chapter 5. These results show that the hybrid algorithm is significantly faster than full ray tracing algorithms

Occlusion Textures for Plausible Soft Shadows

International audienceThis paper presents a new approach to compute plausible soft shadows for complex dynamic scenes and rectangular light sources. We estimate the occlusion at each point of the scene using prefiltered occlusion textures, which dynamically approximate the scene geometry. The algorithm is fast and its performance independent of the light's size. Being image-based, it is mostly independent of the scene complexity and type. No a priori information is needed, and there is no caster/receiver separation. This makes the method appealing and easy to use

Shadow Techniques for Interactive and Real-Time Applications

Shadows provide important visual cues for the relative position of objects in threedimensional space. For interactive and real-time applications, e.g. in virtual reality systems or games, the shadow computation needs to be extremely fast, usually synchronized with the displays refresh rate. Using dynamic scenes with many, movable light sources, shadow computation is therefore often the main bottleneck in a rendering system. In this thesis we will discuss this problem in detail: Originating from Williams shadow maps and Crows shadow volumes, we will present hardware accelerated shadow techniques that are able to generate shadows of high-quality while still being fast enough to be used in real-time or interactive applications. We will show algorithms for the computation of hard shadows as well as for the more complex problem of approximating soft shadows caused by area light sources.Schatten sind wichtige visuelle Merkmale die über die relative Position eines Objektes in einem drei-dimensionalen Raum Aufschluss geben. Die Schattenberechnung muss für interaktive und Echtzeit-Anwendungen, wie z.B. Virtual Reality Systeme oder in Spielen, extrem schnell erfolgen, idealerweise synchronisiert mit der Bildwiederholfrequenz. Im Fall von dynamischen Szenen mit vielen, beweglichen Lichtquellen, ist die Berechnung von Schatten oftmals der zeitkritischste Teil innerhalb eines Rendering-Systems. In dieser Dissertation behandeln wir genau dieses Problem im Detail. Ausgehend vonWilliams\u27; Shadow Maps und Crow\u27;s Shadow Volumes werden Hardwarebeschleunigte Schattentechniken vorgestellt, die Schatten von hoher Qualität erzeugen können, aber trotzdem so effizient sind, dass sie für Echtzeit- und interaktive Anwendungen eingesetzt werden können. Wir werden sowohl Algorithmen zur Berechnung harter Schatten beschreiben, als auch das schwierigere Problem der Approximation von sanften Schatten, wie sie z.B. bei Flächenlichtquellen entstehen, behandeln

Geometric Transformation Techniques for Digital Images: A Survey

This survey presents a wide collection of algorithms for the geometric transformation of digital images. Efficient image transformation algorithms are critically important to the remote sensing, medical imaging, computer vision, and computer graphics communities. We review the growth of this field and compare all the described algorithms. Since this subject is interdisciplinary, emphasis is placed on the unification of the terminology, motivation, and contributions of each technique to yield a single coherent framework. This paper attempts to serve a dual role as a survey and a tutorial. It is comprehensive in scope and detailed in style. The primary focus centers on the three components that comprise all geometric transformations: spatial transformations, resampling, and antialiasing. In addition, considerable attention is directed to the dramatic progress made in the development of separable algorithms. The text is supplemented with numerous examples and an extensive bibliography

Improving Filtering for Computer Graphics

When drawing images onto a computer screen, the information in the scene is typically more detailed than can be displayed. Most objects, however, will not be close to the camera, so details have to be filtered out, or anti-aliased, when the objects are drawn on the screen. I describe new methods for filtering images and shapes with high fidelity while using computational resources as efficiently as possible. Vector graphics are everywhere, from drawing 3D polygons to 2D text and maps for navigation software. Because of its numerous applications, having a fast, high-quality rasterizer is important. I developed a method for analytically rasterizing shapes using wavelets. This approach allows me to produce accurate 2D rasterizations of images and 3D voxelizations of objects, which is the first step in 3D printing. I later improved my method to handle more filters. The resulting algorithm creates higher-quality images than commercial software such as Adobe Acrobat and is several times faster than the most highly optimized commercial products. The quality of texture filtering also has a dramatic impact on the quality of a rendered image. Textures are images that are applied to 3D surfaces, which typically cannot be mapped to the 2D space of an image without introducing distortions. For situations in which it is impossible to change the rendering pipeline, I developed a method for precomputing image filters over 3D surfaces. If I can also change the pipeline, I show that it is possible to improve the quality of texture sampling significantly in real-time rendering while using the same memory bandwidth as used in traditional methods

Visually pleasing real-time global illumination rendering for fully-dynamic scenes

Global illumination (GI) rendering plays a crucial role in the photo-realistic rendering of virtual scenes. With the rapid development of graphics hardware, GI has become increasingly attractive even for real-time applications nowadays. However, the computation of physically-correct global illumination is time-consuming and cannot achieve real-time, or even interactive performance. Although the realtime GI is possible using a solution based on precomputation, such a solution cannot deal with fully-dynamic scenes. This dissertation focuses on solving these problems by introducing visually pleasing real-time global illumination rendering for fully-dynamic scenes. To this end, we develop a set of novel algorithms and techniques for rendering global illumination effects using the graphics hardware. All these algorithms not only result in real-time or interactive performance, but also generate comparable quality to the previous works in off-line rendering. First, we present a novel implicit visibility technique to circumvent expensive visibility queries in hierarchical radiosity by evaluating the visibility implicitly. Thereafter, we focus on rendering visually plausible soft shadows, which is the most important GI effect caused by the visibility determination. Based on the pre-filtering shadowmapping theory, wesuccessively propose two real-time soft shadow mapping methods: "convolution soft shadow mapping" (CSSM) and "variance soft shadow mapping" (VSSM). Furthermore, we successfully apply our CSSM method in computing the shadow effects for indirect lighting. Finally, to explore the GI rendering in participating media, we investigate a novel technique to interactively render volume caustics in the single-scattering participating media.Das Rendern globaler Beleuchtung ist für die fotorealistische Darstellung virtueller Szenen von entscheidender Bedeutung. Dank der rapiden Entwicklung der Grafik-Hardware wird die globale Beleuchtung heutzutage sogar für Echtzeitanwendungen immer attraktiver. Trotz allem ist die Berechnung physikalisch korrekter globaler Beleuchtung zeitintensiv und interaktive Laufzeiten können mit "standard Hardware" noch nicht erzielt werden. Obwohl das Rendering auf der Grundlage von Vorberechnungen in Echtzeit möglich ist, kann ein solcher Ansatz nicht auf voll-dynamische Szenen angewendet werden. Diese Dissertation zielt darauf ab, das Problem der globalen Beleuchtungsberechnung durch Einführung von neuen Techniken für voll-dynamische Szenen in Echtzeit zu lösen. Dazu stellen wir eine Reihe neuer Algorithmen vor, die die Effekte der globaler Beleuchtung auf der Grafik-Hardware berechnen. All diese Algorithmen erzielen nicht nur Echtzeit bzw. interaktive Laufzeiten sondern liefern auch eine Qualität, die mit bisherigen offline Methoden vergleichbar ist. Zunächst präsentieren wir eine neue Technik zur Berechnung impliziter Sichtbarkeit, die aufwändige Sichbarkeitstests in hierarchischen Radiosity-Datenstrukturen vermeidet. Anschliessend stellen wir eine Methode vor, die weiche Schatten, ein wichtiger Effekt für die globale Beleuchtung, in Echtzeit berechnet. Auf der Grundlage der Theorie über vorgefilterten Schattenwurf, zeigen wir nacheinander zwei Echtzeitmethoden zur Berechnung weicher Schattenwürfe: "Convolution Soft Shadow Mapping" (CSSM) und "Variance Soft Shadow Mapping" (VSSM). Darüber hinaus wenden wir unsere CSSM-Methode auch erfolgreich auf den Schatteneffekt in der indirekten Beleuchtung an. Abschliessend präsentieren wir eine neue Methode zum interaktiven Rendern von Volumen-Kaustiken in einfach streuenden, halbtransparenten Medien