Perceptually-Driven Decision Theory for Interactive Realistic Rendering

this paper we introduce a new approach to realistic rendering at interactive rates on commodity graphics hardware. The approach uses efficient perceptual metrics within a decision theoretic framework to optimally order rendering operations, producing images of the highest visual quality within system constraints. We demonstrate the usefulness of this approach for various applications such as diffuse texture caching, environment map prioritization and radiosity mesh simplification. Although here we address the problem of realistic rendering at interactive rates, the perceptually-based decision theoretic methodology we introduce can be usefully applied in many areas of computer graphic

Efficient global illumination for dynamic scenes

The production of high quality animations which feature compelling lighting effects is computationally a very heavy task when traditional rendering approaches are used where each frame is computed separately. The fact that most of the computation must be restarted from scratch for each frame leads to unnecessary redundancy. Since temporal coherence is typically not exploited, temporal aliasing problems are also more difficult to address. Many small errors in lighting distribution cannot be perceived by human observers when they are coherent in temporal domain. However, when such a coherence is lost, the resulting animations suffer from unpleasant flickering effects. In this thesis, we propose global illumination and rendering algorithms, which are designed specifically to combat those problems. We achieve this goal by exploiting temporal coherence in the lighting distribution between the subsequent animation frames. Our strategy relies on extending into temporal domain wellknown global illumination and rendering techniques such as density estimation path tracing, photon mapping, ray tracing, and irradiance caching, which have been originally designed to handle static scenes only. Our techniques mainly focus on the computation of indirect illumination, which is the most expensive part of global illumination modelling.Die Erstellung von hochqualitativen 3D-Animationen mit anspruchsvollen Lichteffekten ist für traditionelle Renderinganwendungen, bei denen jedes Bild separat berechnet wird, sehr aufwendig. Die Tatsache jedes Bild komplett neu zu berechnen führt zu unnötiger Redundanz. Wenn temporale Koherenz vernachlässigt wird, treten unter anderem auch schwierig zu behandelnde temporale Aliasingprobleme auf. Viele kleine Fehler in der Beleuchtungsberechnung eines Bildes können normalerweise nicht wahr genommen werden. Wenn jedoch die temporale Koherenz zwischen aufeinanderfolgenden Bildern fehlt, treten störende Flimmereffekte auf. In dieser Arbeit stellen wir globale Beleuchtungsalgorithmen vor, die die oben genannten Probleme behandeln. Dies erreichen wir durch Ausnutzung von temporaler Koherenz zwischen aufeinanderfolgenden Einzelbildern einer Animation. Unsere Strategy baut auf die klassischen globalen Beleuchtungsalgorithmen wie "Path tracing", "Photon Mapping" und "Irradiance Caching" auf und erweitert diese in die temporale Domäne. Dabei beschränken sich unsereMethoden hauptsächlich auf die Berechnung indirekter Beleuchtung, welche den zeitintensivsten Teil der globalen Beleuchtungsberechnung darstellt

A Multi-Scale Roughness Metric for 3D Watermarking Quality Assessment

In this paper an objective metric to measure the perceptual quality of watermarked 3D meshes is presented. The metric relies on a multiscale measurement of the roughness of 3D meshes before and after the watermark insertion. The validity of the proposed metric has been tested against a number of different 3D watermarking algorithms, showing an excellent match with the subjective evaluation of the quality derived from pshycovisual experiments

Efficient global illumination for dynamic scenes

The production of high quality animations which feature compelling lighting effects is computationally a very heavy task when traditional rendering approaches are used where each frame is computed separately. The fact that most of the computation must be restarted from scratch for each frame leads to unnecessary redundancy. Since temporal coherence is typically not exploited, temporal aliasing problems are also more difficult to address. Many small errors in lighting distribution cannot be perceived by human observers when they are coherent in temporal domain. However, when such a coherence is lost, the resulting animations suffer from unpleasant flickering effects. In this thesis, we propose global illumination and rendering algorithms, which are designed specifically to combat those problems. We achieve this goal by exploiting temporal coherence in the lighting distribution between the subsequent animation frames. Our strategy relies on extending into temporal domain wellknown global illumination and rendering techniques such as density estimation path tracing, photon mapping, ray tracing, and irradiance caching, which have been originally designed to handle static scenes only. Our techniques mainly focus on the computation of indirect illumination, which is the most expensive part of global illumination modelling.Die Erstellung von hochqualitativen 3D-Animationen mit anspruchsvollen Lichteffekten ist für traditionelle Renderinganwendungen, bei denen jedes Bild separat berechnet wird, sehr aufwendig. Die Tatsache jedes Bild komplett neu zu berechnen führt zu unnötiger Redundanz. Wenn temporale Koherenz vernachlässigt wird, treten unter anderem auch schwierig zu behandelnde temporale Aliasingprobleme auf. Viele kleine Fehler in der Beleuchtungsberechnung eines Bildes können normalerweise nicht wahr genommen werden. Wenn jedoch die temporale Koherenz zwischen aufeinanderfolgenden Bildern fehlt, treten störende Flimmereffekte auf. In dieser Arbeit stellen wir globale Beleuchtungsalgorithmen vor, die die oben genannten Probleme behandeln. Dies erreichen wir durch Ausnutzung von temporaler Koherenz zwischen aufeinanderfolgenden Einzelbildern einer Animation. Unsere Strategy baut auf die klassischen globalen Beleuchtungsalgorithmen wie "Path tracing", "Photon Mapping" und "Irradiance Caching" auf und erweitert diese in die temporale Domäne. Dabei beschränken sich unsereMethoden hauptsächlich auf die Berechnung indirekter Beleuchtung, welche den zeitintensivsten Teil der globalen Beleuchtungsberechnung darstellt

Watermarked 3D Object Quality Assessment

This work concerns the developing of new perceptual metrics for 3D watermarking quality assessment. Any water- marking algorithm, to be effective, requires that the distortions is inevitably introduces into the watermarked media is imperceptible. This requirements is particularly severe for watermarking of 3D objects where the visual quality of the original model has to be preserved, i.e. the visual aspect of the watermarked object have to be the same of the original one. Several methods based on the knowledge of Human Visual System (HVS) have been developed to achieve this goal for still images and video watermarking. Since now, no similar techniques for watermarking of 3D objects exist. Here, we propose a novel experimental methodology for subjective evaluations of 3D objects and two perceptual metrics for quality assessment of watermarked 3D objects. Such metrics have been developed combining roughness estimation of model surface with psychophysical data collected by subjective experiments based on the proposed methodology. The performances of the proposed metrics are deeply analyzed

Perceptual model for adaptive local shading and refresh rate

When the rendering budget is limited by power or time, it is necessary to find the combination of rendering parameters, such as resolution and refresh rate, that could deliver the best quality. Variable-rate shading (VRS), introduced in the last generations of GPUs, enables fine control of the rendering quality, in which each 16×16 image tile can be rendered with a different ratio of shader executions. We take advantage of this capability and propose a new method for adaptive control of local shading and refresh rate. The method analyzes texture content, on-screen velocities, luminance, and effective resolution and suggests the refresh rate and a VRS state map that maximizes the quality of animated content under a limited budget. The method is based on the new content-adaptive metric of judder, aliasing, and blur, which is derived from the psychophysical models of contrast sensitivity. To calibrate and validate the metric, we gather data from literature and also collect new measurements of motion quality under variable shading rates, different velocities of motion, texture content, and display capabilities, such as refresh rate, persistence, and angular resolution. The proposed metric and adaptive shading method is implemented as a game engine plugin. Our experimental validation shows a substantial increase in preference of our method over rendering with a fixed resolution and refresh rate, and an existing motion-adaptive techniqu

High-fidelity graphics using unconventional distributed rendering approaches

High-fidelity rendering requires a substantial amount of computational resources to accurately simulate lighting in virtual environments. While desktop computing, with the aid of modern graphics hardware, has shown promise in delivering realistic rendering at interactive rates, real-time rendering of moderately complex scenes is still unachievable on the majority of desktop machines and the vast plethora of mobile computing devices that have recently become commonplace. This work provides a wide range of computing devices with high-fidelity rendering capabilities via oft-unused distributed computing paradigms. It speeds up the rendering process on formerly capable devices and provides full functionality to incapable devices. Novel scheduling and rendering algorithms have been designed to best take advantage of the characteristics of these systems and demonstrate the efficacy of such distributed methods. The first is a novel system that provides multiple clients with parallel resources for rendering a single task, and adapts in real-time to the number of concurrent requests. The second is a distributed algorithm for the remote asynchronous computation of the indirect diffuse component, which is merged with locally-computed direct lighting for a full global illumination solution. The third is a method for precomputing indirect lighting information for dynamically-generated multi-user environments by using the aggregated resources of the clients themselves. The fourth is a novel peer-to-peer system for improving the rendering performance in multi-user environments through the sharing of computation results, propagated via a mechanism based on epidemiology. The results demonstrate that the boundaries of the distributed computing typically used for computer graphics can be significantly and successfully expanded by adapting alternative distributed methods