Tehnike zrcaljenja u Real-Time računalnoj grafici

Reflections have a long history in computer graphics, as they are important for conveying a sense of realism as well as depth and proportion. Their implementations come with a multitude of difficulties, and each solution typically has various trade-offs. Approaches highly depend on the geometry of the reflective surface since curved reflectors are usually more difficult to portray accurately. Techniques can typically be categorized by whether they work with the actual geometry of the reflected objects or with an image of these objects. For curved surfaces, image-based techniques are usually preferred, whereas for planar surfaces the reflected geometry can be used more easily because of the lack of distortion. With current advances in graphics hardware technology, ray tracing is also becoming more viable for real-time applications. Many modern solutions often combine multiple approaches to form a hybrid technique. In this paper, we give an overview of the techniques used in computer graphics applications to create real-time reflections. We highlight the trade-offs that have to be dealt with when choosing a particular technique, as well as their ability to produce interreflections. Finally, we describe how contemporary state-of-the-art rendering engines deal with reflections.Zrcaljenja imaju dugu povijest primjene u računalnoj grafici zbog njihove važnosti u prenošenju realističnosti prikaza te prikaza dubine i omjera na slikama. Pri implementaciji zrcaljenja dolazimo do raznih teškoća i svako novo rješenje često imaju svoju cijenu. Pristupi implementacije ovise o geometriji plohe na kojoj leži prikaz, Što je ploha zakrivljenija, to je teže postići vjerni prikaz. Tehnike možemo kategorizirati u one koje rade sa stvarnom geometrijom zrcaljenih objekata te one koje rade samo sa slikama objekata. Kod zakrivljenih ploha koriste se tehnike bazirane na slikama, dok se kod ravninskih ploha koristi zrcaljena geometrija jer nema iskrivljenja. Zahvaljujući trenutnom razvoju tehnologije grafičkih hardvera, metoda praćenja zraka (ray tracing) postaje sve isplativija u real-time primjeni. Mnoga moderna rješenja kombiniraju razne pristupe i dolazi do hibridnih tehnika. U ovom radu dajemo pregled tehnika korištenih u primjeni računalne grafike za postizanje real-time zrcalnih slika. Naglašavamo probleme koji nastaju pri korištenju određene tehnike te njihove mogućnosti u pogledu stvaranja međuzrcaljenja. Naposljetku, opisujemo kako moderni alati za renderiranje rješavaju probleme zrcaljenj

Ambient occlusion and shadows for molecular graphics

Computer based visualisations of molecules have been produced as early as the 1950s to aid researchers in their understanding of biomolecular structures. An important consideration for Molecular Graphics software is the ability to visualise the 3D structure of the molecule in a clear manner. Recent advancements in computer graphics have led to improved rendering capabilities of the visualisation tools. The capabilities of current shading languages allow the inclusion of advanced graphic effects such as ambient occlusion and shadows that greatly improve the comprehension of the 3D shapes of the molecules. This thesis focuses on finding improved solutions to the real time rendering of Molecular Graphics on modern day computers. The methods of calculating ambient occlusion and both hard and soft shadows are examined and implemented to give the user a more complete experience when navigating large molecular structures

Developing serious games for cultural heritage: a state-of-the-art review

Although the widespread use of gaming for leisure purposes has been well documented, the use of games to support cultural heritage purposes, such as historical teaching and learning, or for enhancing museum visits, has been less well considered. The state-of-the-art in serious game technology is identical to that of the state-of-the-art in entertainment games technology. As a result, the field of serious heritage games concerns itself with recent advances in computer games, real-time computer graphics, virtual and augmented reality and artificial intelligence. On the other hand, the main strengths of serious gaming applications may be generalised as being in the areas of communication, visual expression of information, collaboration mechanisms, interactivity and entertainment. In this report, we will focus on the state-of-the-art with respect to the theories, methods and technologies used in serious heritage games. We provide an overview of existing literature of relevance to the domain, discuss the strengths and weaknesses of the described methods and point out unsolved problems and challenges. In addition, several case studies illustrating the application of methods and technologies used in cultural heritage are presented

Serious Games in Cultural Heritage

Although the widespread use of gaming for leisure purposes has been well documented, the use of games to support cultural heritage purposes, such as historical teaching and learning, or for enhancing museum visits, has been less well considered. The state-of-the-art in serious game technology is identical to that of the state-of-the-art in entertainment games technology. As a result the field of serious heritage games concerns itself with recent advances in computer games, real-time computer graphics, virtual and augmented reality and artificial intelligence. On the other hand, the main strengths of serious gaming applications may be generalised as being in the areas of communication, visual expression of information, collaboration mechanisms, interactivity and entertainment. In this report, we will focus on the state-of-the-art with respect to the theories, methods and technologies used in serious heritage games. We provide an overview of existing literature of relevance to the domain, discuss the strengths and weaknesses of the described methods and point out unsolved problems and challenges. In addition, several case studies illustrating the application of methods and technologies used in cultural heritage are presented

Glossy Probe Reprojection for Interactive Global Illumination

International audienceRecent rendering advances dramatically reduce the cost of global illumination. But even with hardware acceleration, complex light paths with multiple glossy interactions are still expensive; our new algorithm stores these paths in precomputed light probes and reprojects them at runtime to provide interactivity. Combined with traditional light maps for diffuse lighting our approach interactively renders all light paths in static scenes with opaque objects. Naively reprojecting probes with glossy lighting is memory-intensive, requires efficient access to the correctly reflected radiance, and exhibits problems at occlusion boundaries in glossy reflections. Our solution addresses all these issues. To minimize memory, we introduce an adaptive light probe parameterization that allocates increased resolution for shinier surfaces and regions of higher geometric complexity. To efficiently sample glossy paths, our novel gathering algorithm reprojects probe texels in a view-dependent manner using efficient reflection estimation and a fast rasterization-based search. Naive probe reprojection often sharpens glossy reflections at occlusion boundaries, due to changes in parallax. To avoid this, we split the convolution induced by the BRDF into two steps: we precompute probes using a lower material roughness and apply an adaptive bilateral filter at runtime to reproduce the original surface roughness. Combining these elements, our algorithm interactively renders complex scenes while fitting in the memory, bandwidth, and computation constraints of current hardware

Ray Tracing Gems

This book is a must-have for anyone serious about rendering in real time. With the announcement of new ray tracing APIs and hardware to support them, developers can easily create real-time applications with ray tracing as a core component. As ray tracing on the GPU becomes faster, it will play a more central role in real-time rendering. Ray Tracing Gems provides key building blocks for developers of games, architectural applications, visualizations, and more. Experts in rendering share their knowledge by explaining everything from nitty-gritty techniques that will improve any ray tracer to mastery of the new capabilities of current and future hardware. What you'll learn: The latest ray tracing techniques for developing real-time applications in multiple domains Guidance, advice, and best practices for rendering applications with Microsoft DirectX Raytracing (DXR) How to implement high-performance graphics for interactive visualizations, games, simulations, and more Who this book is for: Developers who are looking to leverage the latest APIs and GPU technology for real-time rendering and ray tracing Students looking to learn about best practices in these areas Enthusiasts who want to understand and experiment with their new GPU

Towards Fully Dynamic Surface Illumination in Real-Time Rendering using Acceleration Data Structures

The improvements in GPU hardware, including hardware-accelerated ray tracing, and the push for fully dynamic realistic-looking video games, has been driving more research in the use of ray tracing in real-time applications. The work described in this thesis covers multiple aspects such as optimisations, adapting existing offline methods to real-time constraints, and adding effects which were hard to simulate without the new hardware, all working towards a fully dynamic surface illumination rendering in real-time.Our first main area of research concerns photon-based techniques, commonly used to render caustics. As many photons can be required for a good coverage of the scene, an efficient approach for detecting which ones contribute to a pixel is essential. We improve that process by adapting and extending an existing acceleration data structure; if performance is paramount, we present an approximation which trades off some quality for a 2–3× improvement in rendering time. The tracing of all the photons, and especially when long paths are needed, had become the highest cost. As most paths do not change from frame to frame, we introduce a validation procedure allowing the reuse of as many as possible, even in the presence of dynamic lights and objects. Previous algorithms for associating pixels and photons do not robustly handle specular materials, so we designed an approach leveraging ray tracing hardware to allow for caustics to be visible in mirrors or behind transparent objects.Our second research focus switches from a light-based perspective to a camera-based one, to improve the picking of light sources when shading: photon-based techniques are wonderful for caustics, but not as efficient for direct lighting estimations. When a scene has thousands of lights, only a handful can be evaluated at any given pixel due to time constraints. Current selection methods in video games are fast but at the cost of introducing bias. By adapting an acceleration data structure from offline rendering that stochastically chooses a light source based on its importance, we provide unbiased direct lighting evaluation at about 30 fps. To support dynamic scenes, we organise it in a two-level system making it possible to only update the parts containing moving lights, and in a more efficient way.We worked on top of the new ray tracing hardware to handle lighting situations that previously proved too challenging, and presented optimisations relevant for future algorithms in that space. These contributions will help in reducing some artistic constraints while designing new virtual scenes for real-time applications

Towards Predictive Rendering in Virtual Reality

The strive for generating predictive images, i.e., images representing radiometrically correct renditions of reality, has been a longstanding problem in computer graphics. The exactness of such images is extremely important for Virtual Reality applications like Virtual Prototyping, where users need to make decisions impacting large investments based on the simulated images. Unfortunately, generation of predictive imagery is still an unsolved problem due to manifold reasons, especially if real-time restrictions apply. First, existing scenes used for rendering are not modeled accurately enough to create predictive images. Second, even with huge computational efforts existing rendering algorithms are not able to produce radiometrically correct images. Third, current display devices need to convert rendered images into some low-dimensional color space, which prohibits display of radiometrically correct images. Overcoming these limitations is the focus of current state-of-the-art research. This thesis also contributes to this task. First, it briefly introduces the necessary background and identifies the steps required for real-time predictive image generation. Then, existing techniques targeting these steps are presented and their limitations are pointed out. To solve some of the remaining problems, novel techniques are proposed. They cover various steps in the predictive image generation process, ranging from accurate scene modeling over efficient data representation to high-quality, real-time rendering. A special focus of this thesis lays on real-time generation of predictive images using bidirectional texture functions (BTFs), i.e., very accurate representations for spatially varying surface materials. The techniques proposed by this thesis enable efficient handling of BTFs by compressing the huge amount of data contained in this material representation, applying them to geometric surfaces using texture and BTF synthesis techniques, and rendering BTF covered objects in real-time. Further approaches proposed in this thesis target inclusion of real-time global illumination effects or more efficient rendering using novel level-of-detail representations for geometric objects. Finally, this thesis assesses the rendering quality achievable with BTF materials, indicating a significant increase in realism but also confirming the remainder of problems to be solved to achieve truly predictive image generation

Gerçek zamanlı sahnelerin ışıklandırılmasına yardımcı, dinamik voxelleştirme teknikleri.

In this thesis, we focus on approximating indirect illumination on real-time applications to visualize realistic scenes. In order to approximate indirect illumination we provide a fast sparse voxel tree structure for highly dynamic scenes. Our system tries to cover traditional real-time animation methods including dynamic non-deforming objects and objects that deform with bone transformations. The voxel scene data structure is designed for fully dynamic objects and eliminates the voxelization of the dynamic objects per frame which in turn facilitates efficient realistic rendering. We combine this new scene information structure with the widely used real-time rendering techniques and these techniques’ data structures such as shadow mapping and deferred rendering to provide an efficient cone ray-casting algorithm that achieves global illumination in real-time. M.S. - Master of Scienc

Augmented Reality Framework and Demonstrator

Augmenting the real-world with digital information can improve the human perception in many ways. In recent years, a large amount of research has been conducted in the field of Augmented Reality (AR) and related technologies. Subsequently, different AR systems have been developed for the use in different areas such as medical, education, military, and entertainment. This thesis investigates augmented reality systems and challenges of realistic rendering in AR environment. Besides, an object-oriented framework, named ThirdEye, has been designed and implemented in order to facilitate the process of developing augmented reality applications for experimental purposes. This framework has been developed in two versions for desktop and mobile platforms. With ThirdEye, it is easier to port the same AR demo application to both platforms, manage and modify all AR demo application components, compared to the various existing libraries. Each feature that the ThirdEye framework includes, may be provided by other existing libraries separately but this framework provides those features in an easy-to-use manner. In order to evaluate usability and performance of ThirdEye and also for demonstrating challenges of simulating some of the light effects in the AR environment, such as shadow and refraction, several AR demos were developed using this framework. Performance of the implemented AR demos were benchmarked and bottlenecks of different components of the framework were investigated. This thesis explains the structure of the ThirdEye framework, its main components and the employed technologies and the Software Development Kits (SDKs). Furthermore, by using a simple demo, it is explained how this framework can be utilized to develop an AR application step by step. Lastly, several ideas for future development are described