Results 1  10
of
12
The Irradiance Volume
, 1996
"... This thesis presents a volumetric representation for the global illumination within a space based on the radiometric quantity irradiance. We call this representation the irradiance volume. Although irradiance is traditionally computed only for surfaces, its de nition can be naturally extended to all ..."
Abstract

Cited by 79 (8 self)
 Add to MetaCart
This thesis presents a volumetric representation for the global illumination within a space based on the radiometric quantity irradiance. We call this representation the irradiance volume. Although irradiance is traditionally computed only for surfaces, its de nition can be naturally extended to all points and directions in space. The irradiance volume supports the reconstruction of believable approximations to the illumination in situations that overwhelm traditional global illumination algorithms. Atheoretical basis for the irradiance volume is discussed and the methods and issues involved with building the volume are described. The irradiance volume method is tested within several situations in which the use of traditional global illumination methods is impractical, and is shown to provide good performance.
Accelerating Volume Animation by SpaceLeaping
, 1993
"... f i In this paper we present a method for speeding the process of volume rendering a sequence o mages. Speedup is based on exploiting coherency between consecutive images to shorten the n path rays take through the volume. This is achieved by providing each ray with information eeded to leap over th ..."
Abstract

Cited by 66 (9 self)
 Add to MetaCart
f i In this paper we present a method for speeding the process of volume rendering a sequence o mages. Speedup is based on exploiting coherency between consecutive images to shorten the n path rays take through the volume. This is achieved by providing each ray with information eeded to leap over the empty space and commence volume traversal at the vicinity of mean  b ingful data. The algorithm starts by projecting the volume into a Cbuffer (Coordinates uffer) which stores, at each pixel location, the objectspace coordinates of the first nonempty s t voxel visible from that pixel. For each change in the viewing parameters, the Cbuffer i ransformed accordingly. In the case of rotation the transformed Cbuffer goes through a pro  b cess of eliminating coordinates that possibly became hidden. The remaining values in the C uffer serve as an estimate of the point where the new rays should start their volume traverc sal. This spaceleaping method can be combined with existing accele...
Radiance Interpolants for Accelerated BoundedError Ray Tracing
 ACM Transactions on Graphics
, 1999
"... this paper, we present a system that exploits objectspace, rayspace, imagespace and temporal coherence to accelerate ray tracing. Our system uses persurface interpolants to approximate radiance, while conservatively bounding error. The techniques we introduce in this paper should enhance both int ..."
Abstract

Cited by 53 (5 self)
 Add to MetaCart
this paper, we present a system that exploits objectspace, rayspace, imagespace and temporal coherence to accelerate ray tracing. Our system uses persurface interpolants to approximate radiance, while conservatively bounding error. The techniques we introduce in this paper should enhance both interactive and batch ray tracers.
Theory and Application of Specular Path Perturbation
, 2000
"... In this paper we apply perturbation methods to the problem of computing specular reflections in curved surfaces. The key idea is to generate families of closely related optical paths by expanding a given path into a highdimensional Taylor series. Our path perturbation method is based on closedform ..."
Abstract

Cited by 27 (2 self)
 Add to MetaCart
In this paper we apply perturbation methods to the problem of computing specular reflections in curved surfaces. The key idea is to generate families of closely related optical paths by expanding a given path into a highdimensional Taylor series. Our path perturbation method is based on closedform expressions for linear and higherorder approximations of ray paths, which are derived using Fermat's Variation Principle and the Implicit Function Theorem. The perturbation formula presented here holds for general multiplebounce reflection paths and provides a mathematical foundation for exploiting path coherence in ray tracing acceleration techniques and incremental rendering. To illustrate its use, we describe an algorithm for fast approximation of specular reflections on curved surfaces; the resulting images are of high accuracy and nearly indistinguishable from ray traced images. Keywords: perturbation theory, implicit surfaces, optics, ray tracing, specular reflection 1 1 Introduct...
Multiple Viewpoint Rendering
 in Computer Graphics, SIGGRAPH 98 Proceedings, ACM
, 1996
"... This paper presents a method for efficiently rendering a sequence of regularly spaced perspectives of a scene. The algorithm presented, called Multiple Viewpoint Rendering (MVR), exploits perspective coherence by rendering epipolar plane images. The computer graphics camera geometry is constrained t ..."
Abstract

Cited by 16 (1 self)
 Add to MetaCart
This paper presents a method for efficiently rendering a sequence of regularly spaced perspectives of a scene. The algorithm presented, called Multiple Viewpoint Rendering (MVR), exploits perspective coherence by rendering epipolar plane images. The computer graphics camera geometry is constrained to produce epipolar plane images with linear features. Transformation and shading operations can be performed once per image sequence instead of once per view. Geometric position, color, and texture coordinates can be computed using linear interpolation. Both view independent and dependent shading algorithms are supported. Both one and twodimensional grids of perspectives can be rendered. Details of a hardwareaccelerated implementation of a multiple viewpoint polygon renderer are given. 1 Introduction Most of the time, photography captures information about the world as seen from a single viewpoint. A still camera's single lens records a scene as it appears at one instant, while a movie cam...
BoundedError Interactive Ray Tracing
, 1998
"... Ray tracing, which computes radiance, is traditionally regarded as an offline rendering algorithm that is too slow for interactive use. In this paper, we present an interactive system that uses 4D interpolants to approximate radiance, while providing guaranteed error bounds. Our system exploits the ..."
Abstract

Cited by 9 (2 self)
 Add to MetaCart
Ray tracing, which computes radiance, is traditionally regarded as an offline rendering algorithm that is too slow for interactive use. In this paper, we present an interactive system that uses 4D interpolants to approximate radiance, while providing guaranteed error bounds. Our system exploits the objectspace, rayspace, imagespace and temporal coherence in radiance to accelerate ray tracing. Our system explicitly decouples the two operations of the ray tracer  shading computation and visibility determination at each pixel, which we call pixel assignment. Rendering is accelerated by approximating the shading computation while guaranteeing correct pixel assignment. Without any preprocessing, the system lazily collects 4D radiance samples, which are quadrilinearly interpolated to approximate radiance. An error predicate conservatively guarantees that the relative error introduced by interpolation is bound by a userspecified ffl. The user can change this parameter to trade off pe...
Coherence in Computer Graphics
, 1992
"... Coherence denotes similarities between items or entities. It describes the extent to which these items or entities are locally constant. An introduction to coherence and a survey of various types of coherence, that are used in computer graphics, are given. Techniques and data structures for exploiti ..."
Abstract

Cited by 7 (1 self)
 Add to MetaCart
Coherence denotes similarities between items or entities. It describes the extent to which these items or entities are locally constant. An introduction to coherence and a survey of various types of coherence, that are used in computer graphics, are given. Techniques and data structures for exploiting coherence in computer graphics are described. Incremental techniques, bounding volume schemes, subdivision techniques and several geometric data structures are discussed in more detail. Applications of coherence principles to computer graphics are treated and a survey of previous research is done. INTRODUCTION General remarks The widespread application of coherence principles allows only a vague definition of coherence. Without giving a formal definition coherence denotes, in the context of this paper, similarities between items or entities. It describes the extent to which these items or entities are locally constant. In many situations properties do not change drastically but rather in ...
EXPERIENCES WITH MESHLIKE COMPUTATIONS USING PREDICTION BINARY TREES ∗
"... Abstract. In this paper we aim at exploiting the temporal coherence among successive phases of a computation, in order to implement a loadbalancing technique in meshlike computations to be mapped on a cluster of processors. A key concept, on which the load balancing schema is built on, is the use ..."
Abstract

Cited by 2 (2 self)
 Add to MetaCart
Abstract. In this paper we aim at exploiting the temporal coherence among successive phases of a computation, in order to implement a loadbalancing technique in meshlike computations to be mapped on a cluster of processors. A key concept, on which the load balancing schema is built on, is the use of a Predictor component that is in charge of providing an estimation of the unbalancing between successive phases. By using this information, our method partitions the computation in balanced tasks through the Prediction Binary Tree (PBT). At each new phase, current PBT is updated by using previous phase computing time for each task as nextphase’s cost estimate. The PBT is designed so that it balances the load across the tasks as well as reduces dependency among processors for higher performances. Reducing dependency is obtained by using rectangular tiles of the mesh, of almostsquare shape (i. e. one dimension is at most twice the other). By reducing dependency, one can reduce interprocessors communication or exploit local dependencies among tasks (such as data locality). Furthermore, we also provide two heuristics which take advantage of datalocality. Our strategy has been assessed on a significant problem, Parallel Ray Tracing. Our implementation shows a good scalability, and improves performance in both cheaper commodity cluster and high performance clusters with low latency networks. We report different measurements showing that tasks granularity is a key point for the performances of our decomposition/mapping strategy. Key words: scheduling, load balancing, performance prediction, meshlike computation, performance evaluation. 1. Introduction.
A Spatially and Temporally Coherent Visibility Algorithm
, 1996
"... Efficiently identifying polygons that are visible from a changing synthetic viewpoint is an important problem in computer graphics. In many complex geometric models, most parts of the model are invisible from the instantaneous viewpoint. Despite this, hiddensurface algorithms like the zbuffer or BS ..."
Abstract

Cited by 1 (0 self)
 Add to MetaCart
Efficiently identifying polygons that are visible from a changing synthetic viewpoint is an important problem in computer graphics. In many complex geometric models, most parts of the model are invisible from the instantaneous viewpoint. Despite this, hiddensurface algorithms like the zbuffer or BSP tree often expend significant computation resources processing invisible portions of the model. In this paper, we present a new approach to the visibility problem that exploits the presence of large occluders near the viewpoint to identify a superset of visible polygons, without touching most invisible polygons. The salient features of this algorithm are: it is conservative, i.e., it overestimates the set of visible polygons; it exploits spatial coherence by using a hierarchical data structure; it exploits temporal coherence by reusing visibility information computed for previous viewpoints; and it is easily parallelizable. Keywords: Conservative visibility, temporal coherence, spatial coh...