We present a method for rendering scenes with fine detail via an object called a texel, a rendering primitive inspired by volume den-sities mixed with anisotropic lighting models. This technique solves a long outstanding problem in image synthesis: the rendering of furry surfaces.

Shadows are essential to realistic and visually appealing images, but they are di cult to compute in most display environments. This survey will characterize the various types of shadows, describe most existing shadow algorithms, and for each one discuss their complexities, their advantages and their shortcomings. The types of shadows examined are hard shadows, soft shadows, shadows of transparent objects, and shadows for complex modeling primitives. For each type, we examine shadow algorithms within various rendering techniques. The goal of the survey is to provide readers with enough background and insight on the various methods to allow themtochoose the algorithm best suited to their needs. It is also hoped that our analysis will help identify the areas that need more research, and point to possible solutions.

This paper presents a technique for estimating the spatially-varying reflectance properties of a surface based on its appearance during a single pass of a linear light source. By using a linear light rather than a point light source as the illuminant, we are able to reliably observe and estimate the diffuse color, specular color, and specular roughness of each point of the surface. The reflectometry apparatus we use is simple and inexpensive to build, requiring a single direction of motion for the light source and a fixed camera viewpoint. Our model fitting technique first renders a reflectance table of how diffuse and specular reflectance lobes would appear under moving linear light source illumination. Then, for each pixel we compare its series of intensity values to the tabulated reflectance lobes to determine which reflectance model parameters most closely produce the observed reflectance values. Using two passes of the linear light source at different angles, we can also estimate per-pixel surface normals as well as the reflectance parameters. Additionally our system records a per-pixel height map for the object and estimates its per-pixel translucency. We produce real-time renderings of the captured objects using a custom hardware shading algorithm. We apply the technique to a test object exhibiting a variety of materials as well as to an illuminated manuscript with gold lettering. To demonstrate the technique's accuracy, we compare renderings of the captured models to real photographs of the original objects.

This paper describes the Visibility Octree, a data structure to accelerate 3D navigation through very complex scenes. A conservative visibility algorithm that computes and hierarchically stores the structure at a preprocessing stage is presented. The Visibility Octree is used during navigation and its main contribution is its ability to provide an effective control over the coarseness of the visibility approximation. Tests with indoor ship scenes show that the visibility octree performs well on densely occluded environments. 1 Introduction and previous work This work is focused on the interactive navigation through very complex polygonal models. There are a wide range of applications nowadays whose requirements surpass even the most expensive high-end graphics workstations. To name a few, ship design, architectural design and virtual reality applications have hundreds of thousands or even millions of polygons. Current graphics hardware is not able to cope with these kind of scenes at...

this paper weintroduce two solutions for rendering surfaces illuminated by linear light sources. The #rst is an analytic solution that is exact though a little expensive. The second allows us to compute the e#ects of these light sources inexpensively yet avoiding the sampling problems of standard approaches. When extending the light source to a line, the shadows have to be handled di#erently in order to capture the variation of intensity within the shadow region. An algorithm to compute the umbra and penumbra regions of shadows is presented. This algorithm allows the objects in a scene to not be limited to polygons only.We #rst review shading and the various light sources currently in use in computer graphics. The two solutions are then derived and the shadowing algorithm is introduced. Finally, results are presented and discussed.

Level-of-detail occlusion culling is a novel approach to the management of occluders that can be easily integrated into most current visibility culling algorithms. The main contribution of this paper is an algorithm that automatically generates sets of densely overlapping boxes with enhanced occlusion properties from non-convex subsets. We call this method occluder synthesis because it is not sensitive to the way the objects are tesselated but to the space enclosed by them. The extension of this technique by allowing a bounded amount of image error is also discussed. We show that visibility computations can be based on a multiresolution model which provides several representations of these occluders with varying visibility accuracy. Our tests show that occlusion performance in tesselated scenes is improved severely even if no imageerror is allowed. 1 Introduction Real-time inspection of very large models, with hundreds of thousands of faces, often surpasses the hardware performance o...

This paper will survey most of the major issues that one must deal with when generating realistic images+. Webegin with an overviewofthe rendering process and a quick reviewofvisible surface determination algorithms. We t hen discuss, in more detail, shading, anti-aliasing, texture mapping, shadows, optical effects and close with a discussion of modeling primitives

We present the visibility octree, a new data structure to accelerate 3D navigation through very complex scenes. Our approach employs a conservative visibility technique to compute an approximation to the visibility space partition. This approximation is computed and stored hierarchically at a preprocessing stage. We believe its main contribution to be its ability to provide an effective control over the coarseness of the approximation. A preliminary test with some randomly generated indoor scenes seems to show that the visibility octree will perform well on densely occluded scenes. 1 Introduction This work is focused on the interactive navigation through polygonal models. There is a wide range of applications nowadays whose requirements surpass even the most expensive high-end graphics workstations. To name a few, ship design, architectural design and virtual reality applications have hundreds of thousands or even millions of polygons. Current graphics hardware is not able to cope wit...

In many industrial designs, such as automobiles and electrical products, evaluating the quality of curved surfaces in the design is very important. If the designer can confirm shapes of curved surfaces visually, working with photo-realistic computer generated images, the designer's "sense" is well utilized. In this paper we will demonstrate method for producing images which can be used by designers to evaluate the visual quality of free-form curved surfaces. The method uses the reflected images of cylindrical light sources. It is important that curved surfaces be displayed accurately, without polygonal approximation, and that the generated images be photo-realistic images, including shadows. The shading model presented in this paper satisfies these requirements. Many offices, classrooms, and factories are lit with multiple fluorescent lamps arrayed in parallel rows on the ceiling. The shading technique presented in this paper is applicable to estimation of illuminance distribution in such a...

Environment illumination, which is a complex and distant lighting environment represented by images is often applied to create photo-realistic images. However, creating photo-realistic animations under environment illumination is exceedingly compute intensive. The Precomputed Radiance Transfer (PRT) methods achieve realtime rendering under environment illumination, however, these methods only have a limited application in animation because the objects in the scene cannot be moved or rotated. In this paper, we propose a method for rendering photorealistic animations of dynamic scenes under environment illumination in real time. We notice the fact that when objects are moved or rotated, changes of radiances occur mainly in the regions of shadows cast by other objects. Our method makes a distinction between selfshadow and shadows cast by other objects and computes these two kinds of shadows efficiently.