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

Fuzzy Soft Shadow in Augmented Reality Systems

Realistic soft shadows in Augmented Reality (AR) is a fascinating topic in computer graphics. Many researchers are involved to have a significant improvement on this demand. In this paper, we have presented a new technique to produce soft shadows using one of the well-known methods in mathematics called Fuzzy Logic. Fuzzy logic is taken into account to generate the realistic soft shadows in AR. The wide light source is split into some parts that each of them plays the rule of a single light source. The desired soft shadow is generated by splitting the wide light source into multiple parts and considering each part as a single light source. The method which we called Fuzzy Soft Shadow is employed in AR to enhance the quality of semi-soft shadows and soft shadows

Controllable Shadow Generation Using Pixel Height Maps

Shadows are essential for realistic image compositing. Physics-based shadow rendering methods require 3D geometries, which are not always available. Deep learning-based shadow synthesis methods learn a mapping from the light information to an object's shadow without explicitly modeling the shadow geometry. Still, they lack control and are prone to visual artifacts. We introduce pixel heigh, a novel geometry representation that encodes the correlations between objects, ground, and camera pose. The pixel height can be calculated from 3D geometries, manually annotated on 2D images, and can also be predicted from a single-view RGB image by a supervised approach. It can be used to calculate hard shadows in a 2D image based on the projective geometry, providing precise control of the shadows' direction and shape. Furthermore, we propose a data-driven soft shadow generator to apply softness to a hard shadow based on a softness input parameter. Qualitative and quantitative evaluations demonstrate that the proposed pixel height significantly improves the quality of the shadow generation while allowing for controllability.Comment: 15 pages, 11 figure

Soft Textured Shadow Volume

International audienceEfficiently computing robust soft shadows is a challenging and time consuming task. On the one hand, the quality of image-based shadows is inherently limited by the discrete property of their framework. On the other hand, object-based algorithms do not exhibit such discretization issues but they can only efficiently deal with triangles having a constant transmittance factor. This paper addresses this limitation. We propose a general algorithm for the computation of robust and accurate soft shadows for triangles with a spatially varying transmittance. We then show how this technique can be efficiently included into object-based soft shadow algorithms. This results in unified object-based frameworks for computing robust direct shadows for both standard and perforated triangles in fully animated scenes

Shadow Generation in Augmented Reality: A Complete Survey

This paper provides an overview of the issues and techniques involved in shadow generation in mixed reality environments. Shadow generation techniques in virtual environments are explained briefly. The key factors characterizing the well-known techniques are described in detail and the pros and cons of each technique are discussed. The conceptual perspective, the improvements, and future techniques are also investigated, sum- marized, and analysed in depth. This paper aims to provide researchers with a solid background on the state- of-the-art implementation of shadows in mixed reality. Thus, this could make it easier to choose the most appropriate method to achieve the aims. It is also hoped that this analysis will help researchers find solutions to the problems facing each technique

High quality rendering of protein dynamics in space filling mode

Producing high quality depictions of molecular structures has been an area of academic interest for years, with visualisation tools such as UCSF Chimera, Yasara and PyMol providing a huge number of different rendering modes and lighting effects. However, no visualisation program supports per-pixel lighting effects with shadows whilst rendering a molecular trajectory in space filling mode. In this paper, a new approach to rendering high quality visualisations of molecular trajectories is presented. To enhance depth, ambient occlusion is included within the render. Shadows are also included to help the user perceive relative motions of parts of the protein as they move based on their trajectories. Our approach requires a regular grid to be constructed every time the molecular structure deforms allowing per-pixel lighting effects and ambient occlusion to be rendered every frame, at interactive refresh rates. Two different regular grids are investigated, a fixed grid and a memory efficient compact grid. The algorithms used allow trajectories of proteins comprising of up to 300,000 atoms in size to be rendered at ninety frames per second on a desktop computer using the GPU for general purpose computations. Regular grid construction was found to only take up a small proportion of the total time to render a frame. It was found that despite being slower to construct, the memory efficient compact grid outperformed the theoretically faster fixed grid when the protein being rendered is large, owing to its more efficient memory access patterns. The techniques described could be implemented in other molecular rendering software

Master of Science in Computing

thesisThis document introduces the Soft Shadow Mip-Maps technique, which consists of three methods for overcoming the fundamental limitations of filtering-oriented soft shadows. Filtering-oriented soft shadowing techniques filter shadow maps with varying filter sizes determined by desired penumbra widths. Different varieties of this approach have been commonly applied in interactive and real-time applications. Nonetheless, they share some fundamental limitations. First, soft shadow filter size is not always guaranteed to be the correct size for producing the right penumbra width based on the light source size. Second, filtering with large kernels for soft shadows requires a large number of samples, thereby increasing the cost of filtering. Stochastic approximations for filtering introduce noise and prefiltering leads to inaccuracies. Finally, calculating shadows based on a single blocker estimation can produce significantly inaccurate penumbra widths when the shadow penumbras of different blockers overlap. We discuss three methods to overcome these limitations. First, we introduce a method for computing the soft shadow filter size for a receiver with a blocker distance. Then, we present a filtering scheme based on shadow mip-maps. Mipmap-based filtering uses shadow mip-maps to efficiently generate soft shadows using a constant size filter kernel for each layer, and linear interpolation between layers. Finally, we introduce an improved blocker estimation approach. With the improved blocker estimaiton, we explore the shadow contribution of every blocker by calculating the light occluded by potential blockers. Hence, the calculated penumbra areas correspond to the blockers correctly. Finally, we discuss how to select filter kernels for filtering. These approaches successively solve issues regarding shadow penumbra width calculation apparent in prior techniques. Our result shows that we can produce correct penumbra widths, as evident in our comparisons to ray-traced soft shadows. Nonetheless, the Soft Shadow Mip-Maps technique suffers from light bleeding issues. This is because our method only calculates shadows using the geometry that is available in the shadow depth map. Therefore, the occluded geometry is not taken into consideration, which leads to light bleeding. Another limitation of our method is that using lower resolution shadow mip-map layers limits the resolution of the shadow placement. As a result, when a blocker moves slowly, its shadow follows it with discrete steps, the size of which is determined by the corresponding mip-map layer resolution

Shadow Generation in Mixed Reality: A Comprehensive Survey

This paper provides an overview of the issues and techniques involved in shadow generation in mixed reality environments. Shadow generation techniques in virtual environments are explained briefly. The key factors characterizing the well-known techniques are described in detail and the pros and cons of each technique are discussed. The conceptual perspective, the improvements, and future techniques are also investigated, summarized, and analysed in depth. This paper aims to provide researchers with a solid background on the state-of-the-art implementation of shadows in mixed reality. Thus, this could make it easier to choose the most appropriate method to achieve the aims. It is also hoped that this analysis will help researchers find solutions to the problems facing each technique

Rendering of light shaft and shadow for indoor environments enhancing technique

The ray marching methods have become the most attractive method to provide realism in rendering the effects of light scattering in the participating media of numerous applications. This has attracted significant attention from the scientific community. Up-sampling of ray marching methods is suitable to evaluate light scattering effects such as volumetric shadows and light shafts for rendering realistic scenes, but suffers of cost a lot for rendering. Therefore, some encouraging outcomes have been achieved by using down-sampling of ray marching approach to accelerate rendered scenes. However, these methods are inherently prone to artifacts, aliasing and incorrect boundaries due to the reduced number of sample points along view rays. This study proposed a new enhancing technique to render light shafts and shadows taking into consideration the integration light shafts, volumetric shadows, and shadows for indoor environments. This research has three major phases that cover species of the effects addressed in this thesis. The first phase includes the soft volumetric shadows creation technique called Soft Bilateral Filtering Volumetric Shadows (SoftBiF-VS). The soft shadow was created using a new algorithm called Soft Bilateral Filtering Shadow (SBFS). This technique was started by developing an algorithm called Imperfect Multi-View Soft Shadows (IMVSSs) based on down-sampling multiple point lights (DMPLs) and multiple depth maps, which are processed by using bilateral filtering to obtain soft shadows. Then, down-sampling light scattering model was used with (SBFS) to create volumetric shadows, which was improved using cross-bilateral filter to get soft volumetric shadows. In the second phase, soft light shaft was generated using a new technique called Realistic Real-Time Soft Bilateral Filtering Light Shafts (realTiSoftLS). This technique computed the light shaft depending on down-sampling volumetric light model and depth test, and was interpolated by bilateral filtering to gain soft light shafts. Finally, an enhancing technique for integrating all of these effects that represent the third phase of this research was achieved. The performance of the new enhanced technique was evaluated quantitatively and qualitatively a measured using standard dataset. Results from the experiment showed that 63% of the participants gave strong positive responses to this technique of improving realism. From the quantitative evaluation, the results revealed that the technique has dramatically outpaced the stateof- the-art techniques with a speed of 74 fps in improving the performance for indoor environments