A surface light field is a function that assigns a color to each ray originating on a surface. Surface light fields are well suited to constructing virtual images of shiny objects under complex lighting conditions. This paper presents a framework for construction, compression, interactive rendering, and rudimentary editing of surface light fields of real objects. Generalizations of vector quantization and principal component analysis are used to construct a compressed representation of an object's surface light field from photographs and range scans. A new rendering algorithm achieves interactive rendering of images from the compressed representation, incorporating view-dependent geometric level-of-detail control. The surface light field representation can also be directly edited to yield plausible surface light fields for small changes in surface geometry and reflectance properties.

A separable decomposition of bidirectional reflectance distributions (BRDFs) is used to implement arbitrary reflectances from point sources on existing graphics hardware. Two-dimensional texture mapping and compositing operations are used to reconstruct samples of the BRDF at every pixel at interactive rates. A change of variables, the Gram-Schmidt halfangle/difference vector parameterization, improves separability. Two decomposition algorithms are also presented. The singular value decomposition (SVD) minimizes RMS error. The normalized decomposition is fast and simple, using no more space than what is required for the final representation.

“We’re searching here, trying to get away from the cut and dried handling of things all the way through—everything—and the only way to do it is to leave things open until we have completely explored every bit of it.” –Walt Disney Researchers in nonphotorealistic rendering (NPR) have investigated a variety of techniques to simulate the styles of artists. Recent work has resulted in methods for pen-and-ink illustration, pencil sketching, watercolor, engraving, and silhouette edge rendering. This paper presents real-time methods to emulate cartoon styles. We also present variations on a texture mapping technique to achieve real-time pencil sketching. We demonstrate our method of inking silhouettes, material and mesh boundaries, and crease edges. In addition, we present techniques for emphasizing motion of cartoon objects by introducing geometry into the cartoon scene. The rendering system is integrated with an animation system and a runtime multiresolution mesh (MRM) system to achieve scalability, ensuring real-time performance on any platform. Such solutions allow us to take advantage of evolving hardware in order to make nonphotorealistic animation and rendering achievable on low- and high-end consumer platforms. All of the techniques described can be applied to models created with standard modeling tools and require no additional mark-up information from the modeler.

Real-time graphics hardware is becoming programmable, but this programmable hardware is complex and difficult to use given current APIs. Higher-level abstractions would both increase programmer productivity and make programs more portable. However, it is challenging to raise the abstraction level while still providing high performance. We have developed a real-time procedural shading language system designed to achieve this goal. Our system is organized around multiple computation frequencies. For example, computations may be associated with vertices or with fragments/pixels. Our system’s shading language provides a unified interface that allows a single procedure to include operations from more than one computation frequency. Internally, our system virtualizes limited hardware resources to allow for arbitrarily-complex computations. We map operations to graphics hardware if possible, or to the host CPU as a last resort. This mapping is performed by compiler back-end modules associated with each computation frequency. Our system can map vertex operations to either programmable vertex hardware or to the host CPU, and can map fragment operations to either programmable fragment hardware or to multipass OpenGL. By carefully designing all the components of the system, we are able to generate highly-optimized code. We demonstrate our system running in real-time on a variety of hardware.

A method is presented that can render glossy reflections with arbitrary isotropic bidirectional reflectance distribution functions (BRDFs) at interactive rates using texture mapping. This method is based on the well-known environment map technique for specular reflections.

ing with credit is permitted. To copy otherwise, to republish, to post on servers, or to redistribute to lists, requires prior specific permission and/or a fee. Request permissions from Publications Dept, ACM Inc., fax +1 (212) 869-0481, or permissions@acm.org. Illuminating Micro Geometry Based on Precomputed Visibility Wolfgang Heidrich # Katja Daubert Jan Kautz Hans-Peter Seidel Max-Planck-Institute for Computer Science Abstract Many researchers have been arguing that geometry, bump maps, and BRDFs present a hierarchy of detail that should be exploited for efficient rendering purposes. In practice however, this is often not possible due to inconsistencies in the illumination for these different levels of detail. For example, while bump map rendering often only considers direct illumination and no shadows, geometry-based rendering and BRDFs will mostly also respect shadowing effects, and in many cases even indirect illumination caused by scattered light. In this paper, we pres...

Reflections and refractions are important visual effects that have long been considered too costly for interactive applications. Although most contemporary graphics hardware supports reflections off curved surfaces in the form of environment maps, refractions in thick, solid objects cannot be handled with this approach, and the simplifying assumptions of environment maps also produce visible artifacts for reflections. Only recently have researchers developed techniques for the interactive rendering of true reflections and refractions in curved objects. This paper introduces a new, light field based approach to achieving this goal. The method is based on a strict decoupling of geometry and illumination. Hardware support for all stages of the technique is possible through existing extensions of the OpenGL rendering pipeline. In addition, we also discuss storage issues and introduce methods for handling vector-quantized data with graphics hardware.

In this paper, we present a technique for rendering displacement mapped geometry using current graphics hardware. Our method renders a displacement by slicing through the enclosing volume. The #-test is used to render only the appropriate parts of every slice. The slices need not to be aligned with the base surface, e.g. it is possible to do screen-space aligned slicing. We then

Abstract. Realistic modeling and high-performance rendering of cloth and clothing is a challenging problem. Often these materials are seen at distances where individual stitches and knits can be made out and need to be accounted for. Modeling of the geometry at this level of detail fails due to sheer complexity, while simple texture mapping techniques do not produce the desired quality. In this paper, we describe an efficient and realistic approach that takes into account view-dependent effects such as small displacements causing occlusion and shadows, as well as illumination effects. The method is efficient in terms of memory consumption, and uses a combination of hardware and software rendering to achieve high performance. It is conceivable that future graphics hardware will be flexible enough for full hardware rendering of the proposed method. 1

We propose a new technique for efficiently rendering bidirectional texture functions (BTFs). A 6D BTF describes the appearance of a material as a texture that depends on the lighting and viewing directions. As such, a BTF accommodates self-shadowing, interreflection, and masking effects of a complex material without needing an explicit representation of the small scale geometry. Our method represents the BTF as a set of spatially varying apparent BRDFs, that each encode the reflectance field of a single pixel in the BTF. Each apparent BRDF is decomposed into a product of three or more two-dimensional positive factors using a novel factorization technique, which we call chained matrix factorization (CMF). The proposed factorization technique is fully automatic and suitable for both BRDFs and apparent BRDFs (which typically exhibit off-specular peaks and non-reciprocity).