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.

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

A coordinated use of hardwareprovided bltplanes and rendering pipelines can create fast ray traced quality illumination effects for dynamic environments by using Multi-pass Pipeline Rendering (MPR) techniques. We provide recttrsive reflections and refractions through the use of secondary viewpoints and projective image mapping. We extend the traditional use of shadow volumes to provide global direct illumination effects which fit into our recursive viewpoint paradiim. Hardware surface shading is fit to a physicallybaaed BRDF to provide a better local model, and the framework permits incorporation of indirect illumination as well. Furthermore, material transmittance is approximated using an extension to projective textures. Together, these techniques provide a platform for producing realistic images in highly dynamic environments. While most appropriate for scenes which specular components contribute largely to the secondary illumination, the integration of MPR with indirect racliosity solutions also provides a dynamic solution for highly diffuse environments. These techniques are immediately applicable to areas such as walkthroughs, animation, and interactive dynamic environments to produce more realistic images in near real-time.

While large investments are made in sophisticated graphics hardware, most realistic rendering is still performed off-line using ray trace or radiosity systems. A coordinated use of hardware-provided bitplanes and rendering pipelines can, however, approximate ray trace quality illumination effects in a user-interactive environment, as well as provide the tools necessary for a user to declutter such a complex scene. A variety of common ray trace and radiosity illumination effects are presented using multi-pass rendering in a pipeline architecture. We provide recursive reflections through the use of secondary viewpoints, and present a method for using a homogeneous 2-D projective image mapping to extend this method for refractive transparent surfaces. This paper then introduces the Dual Z-buffer, or DZ-buffer, an evolutionary hardware extension which, along with current framebuffer functions such as stencil planes and accumulation buffers, provides the hardware platform to render non-refr...

In computer graphics, rendering is the process by which an abstract description of a scene is converted to an image. When the scene is complex, or when high-quality images or high frame rates are required, the rendering process becomes computationally demanding. To provide the necessary levels of performance, parallel computing techniques must be brought to bear. Although parallelism has been exploited in computer graphics since the early days of the field, its initial use was primarily in specialized applications. The VLSI revolution of the late 1970Õs and the advent of scalable parallel computers during the late 1980Õs changed this situation. Today, parallel hardware is routinely used in graphics workstations, and numerous software-based rendering systems have been developed for general-purpose parallel architectures. This article provides a broad introduction to the subject of parallel rendering, encompassing both hardware and software systems. The focus is on the underlying concepts and the issues which arise in the design of parallel rendering algorithms and systems. We examine the different types of parallelism and how they can be applied in rendering applications. Concepts from parallel computing, such as data decomposition, task granularity, scalability, and load balancing, are considered in relation to the rendering

We describe new tools for the interactive design of complex, time-dependent lighting in scenes with fixed geometry. The work is motivated by the difficulty in visualizing complicated lighting sequences during the design of large-scale theatrical productions.Fast interaction is achieved regardless of scene and lighting complexity, even when used in conjunction with costly rendering techniques such as radiosity and ray tracing. Time-variant lighting is simulated using linear combinations of static images, each depicting the scene under different lighting conditions. Multiple levels of accuracy facilitate interactive design by trading image quality for fast feedback in a controlled way. Coarse approximations are used in the preliminary design stage to allow for instantaneous feedback, then the sequence is progressively refined by computing basis solutions in order of increasing overall contribution. When changes to the design are required, existing global solutions are re-used to the grea...

Figure 1: Left: An office which receives light through a window on the right wall while the rest of the scene is lit indirectly. Our method avoids explicit visibility computation and our GPU implementation enables the manipulation of the light or objects at 9 frames per second (fps). This includes four iterations of radiance and antiradiance per frame. Center: We can also include an animated character; indirect light is updated at 7.8 fps. Right: Our method naturally handles glossy surfaces; the glossy bust is lit indirectly, since the light points at the ceiling. We reformulate the rendering equation to alleviate the need for explicit visibility computation, thus enabling interactive global illumination on graphics hardware. This is achieved by treating visibility implicitly and propagating an additional quantity, called antiradiance, to compensate for light transmitted extraneously. Our new algorithm shifts visibility computation to simple local iterations by maintaining additional directional antiradiance information with samples in the scene. It is easy to parallelize on a GPU. By correctly treating discretization and filtering, we can compute indirect illumination in scenes with dynamic objects much faster than traditional methods. Our results show interactive update of indirect illumination with moving characters and lights.

We present a framework for interactive lighting design based on linear re-rendering. The rendering operation is linear with respect to light sources, assuming a fixed scene and camera geometry. This linearity means that a scene may be interactively rerendered via linear combination of a set of basis images, each rendered under a particular basis light.We focus on choosing and designing a suitable set of basis lights. We provide examples of bases that allow 1) interactive adjustment of a spotlight direction, 2) interactive adjustment of the position of an area light, and 3) a combination in whichlight sources are adjusted in both position and direction. We discuss a method for reducing the size of the basis using principal components analysis in the image domain.

We describe a new framework for efficiently computing and storing global illumination effects for complex, animated environments. The new framework allows the rapid generation of sequences representing any arbitrary path in a "view space" within an environment in which both the viewer and objects move. The global illumination is stored as time sequences of range-images at base locations that span the view space. We present algorithms for determining locations for these base images, and the time steps required to adequately capture the effects of object motion. We also present algorithms for computing the global illumination in the base images that exploit spatial and temporal coherence by considering direct and indirect illumination separately. We discuss an initial implementation using the new framework. Results and analysis of our implementation demonstrate the effectiveness of the individual phases of the approach; we conclude with an application of the complete framework t...

this paper, which allow us to : 1) locate light sources in complex geometric environments, and drive groups of light sources; 2) take into account spatial luminous intensity distributions and spectral distributions (since the usual wavelength sampling methods used in computer graphics rendering are only applicable in the case of continuous spectrums). Moreover, a set of solutions is presented, which allow us to evaluate the eoeects of changing the light sources properties without re-calculating the entire illumination solution.