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59
Realtime Ray Tracing and its use for Interactive Global Illumination
 In Eurographics State of the Art Reports
, 2003
"... Research on realtime ray tracing has recently made tremendous advances. Algorithmic improvements together with optimized software implementations already allow for interactive frame rates even on a single desktop PC. Furthermore, recent research has demonstrated several options for realizing realtim ..."
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Cited by 68 (11 self)
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Research on realtime ray tracing has recently made tremendous advances. Algorithmic improvements together with optimized software implementations already allow for interactive frame rates even on a single desktop PC. Furthermore, recent research has demonstrated several options for realizing realtime ray tracing on different hardware platforms, e.g. via streaming computation on modern graphics processors (GPUs) or via the use of dedicated ray tracing chips. Together, these developments indicate that realtime ray tracing might indeed become a reality and widely available in the near future. As most of todays global illumination algorithms heavily rely on ray tracing, this availability of fast ray tracing technology creates the potential to finally compute even global illumination – the physically correct simulation of light transport – at interactive rates. In this STAR, we will first cover the different research activities for realizing realtime ray tracing on different hardware architectures – ranging from shared memory systems, over PC clusters, programmable GPUs, to custom ray tracing hardware. Based on this overview, we discuss some of the advanced issues, such as support for dynamic scenes and designs for a suitable ray tracing API. The third part of this STAR then builds on top of these techniques by presenting algorithms for interactive global illumination in complex and dynamic scenes that may contain large numbers of light sources. We believe that the improved quality and the increased realism that global illumination adds to interactive environments makes it a potential “killer application ” for future 3D graphics. 1.
Path Differentials and Applications
 In Rendering Techniques 2001: 12th Eurographics Workshop on Rendering
, 2001
"... Photorealistic rendering algorithms such as Monte Carlo ray tracing sample individual paths to compute images. Noise and aliasing artefacts are usually reduced by supersampling. Knowledge about the neighborhood of the path, such as an estimated footprint, can be used to reduce these artefacts wi ..."
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Cited by 21 (0 self)
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Photorealistic rendering algorithms such as Monte Carlo ray tracing sample individual paths to compute images. Noise and aliasing artefacts are usually reduced by supersampling. Knowledge about the neighborhood of the path, such as an estimated footprint, can be used to reduce these artefacts without having to trace additional paths. The recently introduced ray differentials estimate such a footprint for classical ray tracing, by computing ray derivatives with respect to the image plane. The footprint proves to be useful for filtering textures locally on surfaces. In this paper, we generalize the use of these derivatives to arbitrary path sampling, including general reflection and refraction functions.
Adjoint and importance in rendering: An overview”.
 IEEE Transactions on Visualization and Computer Graphics,
, 2003
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Incoming FirstShot for NonDiffuse Global Illumination
 In Spring Conference on Computer Graphics, Budmerice
, 2000
"... This paper presents a method that can replace the small and medium size lightsources by their effect in nondiffuse global illumination algorithms. Incoming firstshot is a generalization of a preprocessing technique called the firstshot that was developed for speeding up global diffuse radiosity a ..."
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Cited by 11 (8 self)
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This paper presents a method that can replace the small and medium size lightsources by their effect in nondiffuse global illumination algorithms. Incoming firstshot is a generalization of a preprocessing technique called the firstshot that was developed for speeding up global diffuse radiosity algorithms. Alternatively, it can also be approached as a generalization of the directlightsource computation involved in gathering type methods. In order to reduce the prohibitive memory requirements of the original firstshot when it is applied to nondiffuse scenes in a direct manner, the proposed new method computes and stores only the incoming radiance generated by the lightsources and the reflected radiance is obtained from the incoming radiance on the fly taking into account the local BRDF. Since the radiance function of the reflection is smoother and flatter than the original lightsource function, this replacement makes the integrand of the rendering equation have significantly smaller variation, which can speed up global illumination algorithms. The paper also discusses how the firstshot technique can be built into a stochastic iteration algorithm using raybundles, and provides runtime statistics.
Refinement Criteria Based on fDivergences
 EUROGRAPHICS SYMPOSIUM ON RENDERING 2003 PER CHRISTENSEN AND DANIEL COHENOR (EDITORS)
, 2003
"... In several domains a refinement criterion is often needed to decide whether to go on or to stop sampling a signal. When the sampled values are homogeneous enough, we assume that they represent the signal fairly well and we do not need further refinement, otherwise more samples are required, possibly ..."
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Cited by 9 (0 self)
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In several domains a refinement criterion is often needed to decide whether to go on or to stop sampling a signal. When the sampled values are homogeneous enough, we assume that they represent the signal fairly well and we do not need further refinement, otherwise more samples are required, possibly with adaptive subdivision of the domain. For this purpose, a criterion which is very sensitive to variability is necessary. In this paper we present a family of discrimination measures, the fdivergences, meeting this requirement. These functions have been well studied and successfully applied to image processing and several areas of engineering. Two applications to global illumination are shown: oracles for hierarchical radiosity and criteria for adaptive refinement in raytracing. We obtain significantly better results than with classic criteria, showing that fdivergences are worth further investigation in computer graphics.
Interactive caustics using local precomputed irradiance
 In Proc. of Pacific Graphics
, 2004
"... Bright patterns of light focused via reflective or refractive objects onto matte surfaces are called “caustics”. We present a method for rendering dynamic scenes with moving caustics at interactive rates. This technique requires some simplifying assumptions about caustic behavior allowing us to cons ..."
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Cited by 8 (1 self)
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Bright patterns of light focused via reflective or refractive objects onto matte surfaces are called “caustics”. We present a method for rendering dynamic scenes with moving caustics at interactive rates. This technique requires some simplifying assumptions about caustic behavior allowing us to consider it a local spatial property which we sample in a preprocessing stage. Storing the caustic locally limits caustic rendering to a simple lookup. We examine a number of ways to represent this data, allowing us to trade between accuracy, storage, run time, and precomputation time. 1.
Reuse of paths in light source animation
 In Proceedings of Computer Graphics International 2004 (CGI ’04
, 2004
"... In this paper we extend the reuse of paths to the shot from a moving light source. In the classical algorithm new paths have to be cast from each new position of a light source. We show that we can reuse all paths for all positions, obtaining in this way a theoretical maximum speedup equal to the a ..."
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Cited by 8 (4 self)
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In this paper we extend the reuse of paths to the shot from a moving light source. In the classical algorithm new paths have to be cast from each new position of a light source. We show that we can reuse all paths for all positions, obtaining in this way a theoretical maximum speedup equal to the average length of the shooting path. 1.
Weighted Importance Sampling Techniques for Monte Carlo Radiosity
, 2000
"... This paper presents weighted importance sampling techniques for Monte Carlo form factor computation and for stochastic Jacobi radiosity system solution. Weighted importance sampling is a generalisation of importance sampling. The basic idea is to compute aposteriori a correction factor to the i ..."
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Cited by 6 (0 self)
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This paper presents weighted importance sampling techniques for Monte Carlo form factor computation and for stochastic Jacobi radiosity system solution. Weighted importance sampling is a generalisation of importance sampling. The basic idea is to compute aposteriori a correction factor to the importance sampling estimates, based on sample weights accumulated during sampling. With proper weights, the correction factor will compensate for statistical fluctuations and lead to a lower mean square error. Although weighted importance sampling is a simple extension to importance sampling, our experiments indicate that it can lead to a substantial reduction of the error at a very low additional computation and storage cost.
Photorealistic Image Synthesis Using RayBundles
, 2000
"... lightsources, such as point or directional lightsources are preferred here, since their radiance is a Diracdelta like function, which simplifies the integral of equation (2.50) to a sum. These methods take into account only a single reflection of the light coming from the abstract lightsources. Ide ..."
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Cited by 6 (4 self)
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lightsources, such as point or directional lightsources are preferred here, since their radiance is a Diracdelta like function, which simplifies the integral of equation (2.50) to a sum. These methods take into account only a single reflection of the light coming from the abstract lightsources. Ideal mirrors and refracting objects cannot be rendered with these methods. 2. Recursive raytracing Another alternative is to eliminate from the rendering equation those energy contributions which cause the difficulties, and thus give ourselves a simpler problem to solve. For example, if limited level, say n, coupling caused by ideal reflection and refraction were allowed, and we were to ignore the other nonideal components coming from nonabstract lightsources, then the number of surface points which would need to be evaluated to calculate a pixel color can be kept under control. Since the illumination formula contains two terms regarding the coherent components (reflective and refracting l...
Modular Flux Transfer: Efficient Rendering of HighResolution Volumes with Repeated Structures
 APPEARS IN THE SIGGRAPH 2013 PROCEEDINGS
, 2013
"... The highest fidelity images to date of complex materials like cloth use extremely highresolution volumetric models. However, rendering such complex volumetric media is expensive, with bruteforce path tracing often the only viable solution. Fortunately, common volumetric materials (fabrics, finishe ..."
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Cited by 5 (1 self)
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The highest fidelity images to date of complex materials like cloth use extremely highresolution volumetric models. However, rendering such complex volumetric media is expensive, with bruteforce path tracing often the only viable solution. Fortunately, common volumetric materials (fabrics, finished wood, synthesized solid textures) are structured, with repeated patterns approximated by tiling a small number of exemplar blocks. In this paper, we introduce a precomputationbased rendering approach for such volumetric media with repeated structures based on a modular transfer formulation. We model each exemplar block as a voxel grid and precompute voxeltovoxel, patchtopatch, and patchtovoxel flux transfer matrices. At render time, when blocks are tiled to produce a highresolution volume, we accurately compute loworder scattering, with modular flux transfer used to approximate higherorder scattering. We achieve speedups of up to 12 × over path tracing on extremely complex volumes, with minimal loss of quality. In addition, we demonstrate that our approach outperforms photon mapping on these materials.