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Reflectance and texture of realworld surfaces
 ACM TRANS. GRAPHICS
, 1999
"... In this work, we investigate the visual appearance of realworld surfaces and the dependence of appearance on scale, viewing direction and illumination direction. At ne scale, surface variations cause local intensity variation or image texture. The appearance of this texture depends on both illumina ..."
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Cited by 586 (23 self)
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In this work, we investigate the visual appearance of realworld surfaces and the dependence of appearance on scale, viewing direction and illumination direction. At ne scale, surface variations cause local intensity variation or image texture. The appearance of this texture depends on both illumination and viewing direction and can be characterized by the BTF (bidirectional texture function). At su ciently coarse scale, local image texture is not resolvable and local image intensity is uniform. The dependence of this image intensity on illumination and viewing direction is described by the BRDF (bidirectional re ectance distribution function). We simultaneously measure the BTF and BRDF of over 60 di erent rough surfaces, each observed with over 200 di erent combinations of viewing and illumination direction. The resulting BTF database is comprised of over 12,000 image textures. To enable convenient use of the BRDF measurements, we t the measurements to two recent models and obtain a BRDF parameter database. These parameters can be used directly in image analysis and synthesis of a wide variety of surfaces. The BTF, BRDF, and BRDF parameter databases have important implications for computer vision and computer graphics and and each is made publicly available.
A survey of shadow algorithms
 IEEE Computer Graphics and Applications
, 1990
"... Essential to realistic and visually appealing images, shadows are difficult ta compute in most display environments. This survey characterizes the various types of shadows. It also describes most existing shadow algorithms and discusses their complexities, advantages, and shommings. We examine herd ..."
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Cited by 150 (3 self)
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Essential to realistic and visually appealing images, shadows are difficult ta compute in most display environments. This survey characterizes the various types of shadows. It also describes most existing shadow algorithms and discusses their complexities, advantages, and shommings. We examine herd shadows, soft shadbws, shadows of transparent objects, and shadows for complex modeling primitives. For each type, we examine shadow algorithms within various rendswing techniques. This survey attempts to provide readem with enough background and insight on the various rmthods to dow them to choose the algorithm best wpuited to their W. We also hope that our analysis will h&p identify the a m that need more research and point bo possible sotutkms. A shadowa region of relative darkness within an not necessarily attenuate the light it occludes. In fact, illuminated regionoccurs when an object totally or it can concentrate light. However, as is traditional in partially occludes the light. A transparent object does image synthesis, lve will consider a region to be in
Physically Based Lighting Calculations for Computer Graphics
, 1991
"... Realistic image generation is presented in a theoretical formulation that builds from previous work on the rendering equation. Previous and new solution techniques for the global illumination are discussed in the context of this formulation. The basic ..."
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Cited by 78 (13 self)
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Realistic image generation is presented in a theoretical formulation that builds from previous work on the rendering equation. Previous and new solution techniques for the global illumination are discussed in the context of this formulation. The basic
LightDriven Global Illumination with a Wavelet Representation of Light Transport
 In Seventh Eurographics Workshop on Rendering
, 1996
"... We describe the basis of the work he have currently under way to implement a new rendering algorithm called lightdriven global illumination. This algorithm is a departure from conventional raytracing and radiosity renderers which addresses a number of deficiencies intrinsic to those approaches. 1 I ..."
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Cited by 25 (4 self)
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We describe the basis of the work he have currently under way to implement a new rendering algorithm called lightdriven global illumination. This algorithm is a departure from conventional raytracing and radiosity renderers which addresses a number of deficiencies intrinsic to those approaches. 1 Introduction In computer graphics, we use illumination  the study of how light interacts with matter to produce visible scenes  to produce realistic images. Illumination encompasses both local and global phenomena. Local illumination describes the interaction of light with a single, small volume or surface element with given incident and viewing directions. We take the fundamental equation describing local illumination to be L = L e + Z \Omega R N f r (S 0 ; V)L i jN \Delta S 0 j d! 0 i + Z \Omega T N f t (S 0 ; V)L i jN \Delta S 0 j d! 0 i (1) where N is the surface normal, L is the total radiance given off (either L r , reflected, or L t , transmitted) in direct...
An Observational Model for Illuminating Isolated Scratches.
"... In this paper we present an observational model for rendering isolated scratches on otherwise smooth ..."
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Cited by 2 (0 self)
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In this paper we present an observational model for rendering isolated scratches on otherwise smooth
Reflectance Models by Pumping up the Albedo Function
 MACHINE GRAPHICS AND VISION
, 1999
"... The paper introduces a method, called the albedo pumpingup, to derive new, physically plausible BRDFs from an existing one or from any symmetric function. This operation can be applied recursively arbitrary number of times. An important application of this operation is the transformation of the ..."
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Cited by 2 (1 self)
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The paper introduces a method, called the albedo pumpingup, to derive new, physically plausible BRDFs from an existing one or from any symmetric function. This operation can be applied recursively arbitrary number of times. An important application of this operation is the transformation of the Phong and Blinn models in order to make them produce metallic effects. The paper also examines the albedo function of reflectance models and comes to the conclusion that widely used models violate energy balance at grazing angles.
Shading and Inverse Shading from Direct Illumination
, 1994
"... An understanding of light and its interaction with matter is essential to produce images. As the modeling of light sources, light transport and light reflection improves, it becomes possible to render images with increasing realism. The central motivation behind this thesis is to improve realism in ..."
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Cited by 2 (0 self)
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An understanding of light and its interaction with matter is essential to produce images. As the modeling of light sources, light transport and light reflection improves, it becomes possible to render images with increasing realism. The central motivation behind this thesis is to improve realism in computer graphics images by more accurate local shading models and to assist the user to obtain the desired lighting effects with these more complex models. The first part of the thesis addresses the problem of rendering surfaces illuminated by extended (linear and area) light sources. To compute the light reflected by a surface element in a given direction, one needs to determine the unoccluded regions (shadowing) of each light source and then to compute the light reflection (shading) from each of these regions. Traditionally, point light sources are distributed on the lights to approximate both the shadowing and the shading. Instead, an efficient analytical solution is developed for the shading. Shadowing from extended light sources is a fairly expensive process. To give some insights on the complexity of computing shadows, some properties of shadows and algorithms are presented. To reduce the cost of computing shadows from linear light sources, two acceleration schemes, extended from
Computational Methods for Global Illumination and Visualisation of Complex 3D Environments
"... Complex three dimensional environments are visualised by rendering images of these environments as seen from different view points. Over the last three decades rendering techniques have been continuously evolving to greater levels of sophistication in terms of the complexity of environments and the ..."
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Complex three dimensional environments are visualised by rendering images of these environments as seen from different view points. Over the last three decades rendering techniques have been continuously evolving to greater levels of sophistication in terms of the complexity of environments and the realism with which the images are produced. In all image synthesis techniques the fundamental step is computation of the amount and nature of the light from the three dimensional environment reaching the eye in any given direction. Computer graphics rendering techniques carry out this computation by simulating the behaviour of light in the environment. Greater degrees of realism would mean higher correlation between the simulation and the physical world. In the physical world, lighting, reflection and scattering effects are very complicated and subtle. Every object receives light directly from light sources, or indirectly from reflection or scatter by other neighbouring objects. For realistic image synthesis these intraenvironmental effects must be modelled in great detail. This thesis presents the results of a detailed investigation of illumination computation and rendering techniques. The four major contributions of this thesis are: A taxonomy of illumination computation methods. Particle tracing techniques for global illumination computation. The potential equation for illumination computation and the mathematical framework of adjoint equations. Demonstration of the practicality of this new class of global illumination computation algorithms. From a theoretical point of view the primary contribution is the development ofa mathematical framework of adjoint equations which provides the basis for all known illumination computation techniques. This mathematical framework consists of two integral equations the radiance and the potential equation, which are duals of each other. While the radiance equation has been known in one form or the other to the computer graphics community, the potential equation for illumination has been introduced for the first time in this thesis. The signi cance and importance of this new mathematical framework stems from the fact that it not only enables us to review and analyse existing methods but also provides the necessary handles for deriving new and
CrØer, Simuler, Explorer des Univers Naturels sur Ordinateur
"... Abstract So many pixels, and so little time Cet article traite de l'esprit, des approches, et des buts, dans lesquels j'ai mené mes différents travaux. On trouvera néanmoins une synthèse de ces derniers en annexe, à titre d'exemples d'instanciation de ces approches. Ces travaux o ..."
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Abstract So many pixels, and so little time Cet article traite de l'esprit, des approches, et des buts, dans lesquels j'ai mené mes différents travaux. On trouvera néanmoins une synthèse de ces derniers en annexe, à titre d'exemples d'instanciation de ces approches. Ces travaux ont très souvent été menés avec mes étudiants; ceuxci sont donc à inclure quand je dirai je ou mes.