Showing papers on "Computer graphics lighting published in 2005"

Lpics: a hybrid hardware-accelerated relighting engine for computer cinematography

Abstract: In computer cinematography, the process of lighting design involves placing and configuring lights to define the visual appearance of environments and to enhance story elements. This process is labor intensive and time consuming, primarily because lighting artists receive poor feedback from existing tools: interactive previews have very poor quality, while final-quality images often take hours to render.This paper presents an interactive cinematic lighting system used in the production of computer-animated feature films containing environments of very high complexity, in which surface and light appearances are described using procedural RenderMan shaders. Our system provides lighting artists with high-quality previews at interactive framerates with only small approximations compared to the final rendered images. This is accomplished by combining numerical estimation of surface response, image-space caching, deferred shading, and the computational power of modern graphics hardware.Our system has been successfully used in the production of two feature-length animated films, dramatically accelerating lighting tasks. In our experience interactivity fundamentally changes an artist's workflow, improving both productivity and artistic expressiveness.

Survey of Real-Time Rendering Techniques for Crowds

Abstract: Real-time rendering of photo-realistic humans is considerably outside the scope of current consumer-level computer hardware. There are many techniques, which attempt to bridge the gap between what is desired and what is possible. This paper aims to give an overview of the techniques designed to alter the complexity of the model's geometry (level of detail), or replace it with a flat image (visual impostor) and to improve the lighting model (lighting and shadows). Recent years have shown a boom in the power and availability of consumer-level programmable graphics processors, thus techniques that make use of these features are coming to the forefront.

Video-Based Rendering

Abstract: Expectations on computer graphics performance are rising continuously: whether in flight simulators, surgical planning systems, or computer games, ever more realistic rendering results are to be achieved at real-time frame rates. In fact, thanks to progress in graphics hardware as well as rendering algorithms, today visual realism is within reach of off-the-shelf PC graphics boards.

A Model-Based Approach to Image Relighting with a Potential for Real-Time Implementation

Abstract: Image relighting is a very unique special visual effect which promises to have many important practical applica-tions. Image relighting is essentially the process of, given one or more images of some scene, computing what thatscene would look like under some other (arbitrary) lighting conditions, e.g., changing positions and colors of lightsources. Image relighting can for example be used for interior light design. This paper describes an approach toimage relighting which can be implemented to run in real-time by utilizing graphicshardware, as opposed to otherstate-of-the-art approaches which at best run at a few frames per second.Categories and Subject Descriptors (according to ACM CCS) : I.3.4 [Computer Graphics]: Three-DimensionalGraphics and Realism1. IntroductionThis paper addresses the subject of developing relightingtechniques, i.e. techniques allowing a user to completely al-ter the lighting conditions in an image of a real scene. Specif-ically, the paper focuses on techniques providing real-timerelighting functionalities, thus enabling the user to interac-tively change lighting conditions and get "instant" visualfeedback. Figure 1 provides an example of the kind of re-lighting this paper addresses. It should be noted that the workpresented here presumes the availability of three things: 1)an original image of the scene, 2) a 3D model of the scene,and 3) a model of the lighting conditions in the scene at thetime the original image is acquired. We will return to waysin which the two last pieces of knowledge can be obtained.Conceptually image relighting in this manner is a two stepprocess. In the first step all effects of the original lightingconditions are removed, e.g., highlights, shadows, and dif-ferences in shading across surfaces due to varying light in-cidence angles. In the second step the scene is subjected tosome arbitrary new lighting conditions and the appearanceof the scene in these conditions is computed. The secondstep thus "adds" new highlights, shadows and shading etc.Of these two steps the former is the tricky one, while thelatter can be performed using any preferred rendering tech-nique, e.g., ray tracing, radiosity or standard hardware accel-erated approaches. Which rendering technique is employeddepends on the preferred balance between rendering speedand accuracy in handling various lighting phenomena. In or-der to achieve true real-time performance we have chosen touse a hardware accelerated approach for step 2, thus sacri-ficing certain global illumination phenomena.In our approach step 1 is achieved by a computational ap-proach which requires, as stated above, a 3D model of thescene and a model of the original lighting conditions. Alter-natively, one could in principle acquire fronto-parallel digitalimages of the surfaces in the scene under perfectly diffuse,white-balanced lighting conditions and use these images astextures on the 3D model, which is subsequently renderedunder novel lighting conditions (step 2). This would be amechanical or image acquisition approach to step 1, but inreality acquiring such ’clean’ textures devoid of lighting ef-fects is not practical for general scenes.The contributions in this work lie in the specific manner inwhich the operations performed in steps 1 and 2 are carriedout. With the approach described here the two steps can becombined such that the image relighting becomes a matter ofmodulating the original image on a pixel by pixel basis witha "relighting map". The relighting map can be computed in

Enhanced Color and Lighting Model for Computer Graphics Productions

Abstract: A color and lighting method and model for computer graphics productions that automates most of the lighting and compositing processes, creates a light rig that works for at least most of the shots in a given sequence, and allows multiple shots to be run simultaneously without manual interaction.

Computer graphics: what's it all about?

Abstract: I‘d like to take the opportunity to thank all the people that have been so generous in allowing their artwork to be used for Computer Graphics issue covers these past few years. The variety of images has truly been enriching, helping us better understand and appreciate the ongoing development of computer graphics. Software and hardware now allow such a high level of refinement to the degree that common expectations have limited what is visually acceptable to a savvy public, due in part to high profile markets such as television, feature film and video games. For a digital artist that works in a competitive industry, the guidelines are clear – or are they? Something Computer Graphics has tried to be consistent in is promoting the innovation lying at the heart of the technology. It is also one of the common denominators shared by the contributors who say “The guidelines are not clear, so let’s take a closer look.” That is where the distinction between artist, scientist, researcher, teacher and student becomes less defined as they all stumble in the same general direction towards discovery. In school we are not only taught to read and write but how those tools are used to contribute to the arts and how they are used for preserving vision, voice and meaning. Computer graphics is just as much about the abstracts of writing code or digital archetypes, as it is about the tangible language of imagery that manifests. Through emerging digital technology, it lends itself well to preserving the artifacts and rituals of world culture and to experiencing them through the creation of virtual worlds and realities. Programs in institutions of higher education can play a big role in preparing new innovators for their roles in computer graphics by providing resources for their “self” discovery and the means to share the learning experience with others. Computer Graphics has presented a few over the years and I sincerely hope there will be many more in the future that are interested in sharing by sending contributions to the issues that will continue through publication on line.

Guest Editors' Introduction: Computer Graphics in Education

Abstract: This special issue of IEEE CG&A focuses on computer graphics in education. The guest editors present articles featuring innovative ways in which people are teaching computer graphics and ways in which people are using graphics to teach other topics. There is no doubt that the cross-disciplinary application of graphics to teach other topics is one of the things that makes the field so special. Few other areas within computer science are so capable of having such far-reaching effects.

Regularised Anisotropic Nonlinear Diffusion for Rendering Refraction in Volume Graphics.

Abstract: Rendering refraction in volume graphics requires smoothly distributed normals to synthesise good quality visual representations. Such refractive visualisation is more susceptible to noise in the data than visualisations that do not involve refraction. In this paper, we addresses the need for improving the continuity of voxel gradients in discretely sampled volume datasets using nonlinear diffusion methods, which was originally developed for image denoising. We consider the necessity for minimising unnecessary geometrical distortion, detail the functional specification of a volumetric filter for regularised anisotropic nonlinear diffusion (R-ANLD), discuss the further improvements of the filter, and compare the efficacy of the filter with an anisotropic nonlinear diffusion (ANLD) filter as well as a Gaussian filter and a linear diffusion filter. Our results indicate that it is possible to make significant improvements in image quality in refractive rendering without excessive distortion.

Speed Limit 55 [computer graphics]

Abstract: Over the years Andrew Glassner had several topics that he wanted to write about, but haven't gotten around to. So for his parting column, he presents some of his favorite computer graphics topics that never became columns, in the hope that one or more of them might inspire your own investigations. The areas discussed are: sundial simulation and rendering; animal vision; mapping systems; show coherence; color skywriting; weather based graphical art; music; and pixels as numbers.