bluuebunny/crossref_metadata_2025_split huggingface dataset:
Camera Control in Computer Graphics
Authors: Christie Marc , Olivier Patrick , Normand Jean‐Marie 
Published: September 2008

AbstractRecent progress in modelling, animation and rendering means that rich, high fidelity virtual worlds are found in many interactive graphics applications. However, the viewer's experience of a 3D world is dependent on the nature of the virtual cinematography, in particular, the camera position, orientation and motion in relation to the elements of the scene and the action. Camera control encompasses viewpoint computation, motion planning and editing. We present a range of computer graphics applications and draw on insights from cinematographic practice in identifying their different requirements with regard to camera control. The nature of the camera control problem varies depending on these requirements, which range from augmented manual control (semi‐automatic) in interactive applications, to fully automated approaches. We review the full range of solution techniques from constraint‐based to optimization‐based approaches, and conclude with an examination of occlusion management and expressiveness in the context of declarative approaches to camera control.
High Performance GPU‐based Proximity Queries using Distance Fields
Authors: Morvan T. , Reimers M. , Samset E. 
Published: September 2008

Abstract Proximity queries such as closest point computation and collision detection have many applications in computer graphics, including computer animation, physics‐based modelling, augmented and virtual reality. We present efficient algorithms for proximity queries between a closed rigid object and an arbitrary, possibly deformable, polygonal mesh. Using graphics hardware to densely sample the distance field of the rigid object over the arbitrary mesh, we compute minimal proximity and collision response information on the graphics processing unit (GPU) using blending and depth buffering, as well as parallel reduction techniques, thus minimizing the readback bottleneck. Although limited to image‐space resolution, our algorithm provides high and steady performance when compared with other similar algorithms. Proximity queries between arbitrary meshes with hundreds of thousands of triangles and detailed distance fields of rigid objects are computed in a few milliseconds at high‐sampling resolution, even in situations with large overlap.
3D Slit Scanning with Planar Constraints★
Authors: Leotta Matthew J. , Vandergon Austin , Taubin Gabriel 
Published: September 2008

AbstractWe present a planarity constraint and a novel three‐dimensional (3D) point reconstruction algorithm for a multiview laser range slit scanner. The constraint is based on the fact that all observed points on a projected laser line lie on the same plane of laser light in 3D. The parameters of the plane of laser light linearly parametrize a homography between a pair of images of the laser points. This homography can be recovered from point correspondences derived from epipolar geometry. The use of the planar constraint reduces outliers in the reconstruction and allows for the reconstruction of points seen in only one view. We derive an optimal reconstruction of points subject to the planar constraint and compare the accuracy to the suboptimal approach in prior work. We also construct a catadioptric stereo rig with high quality optical components to remove error due to camera synchronization and non‐uniform laser projection. The reconstruction results are compared to prior work that uses inexpensive optics and two cameras.
Diffusion Based Photon Mapping
Authors: Schjøth L. , Sporring J. , Fogh Olsen O. 
Published: September 2008

Abstract Density estimation employed in multi‐pass global illumination algorithms give cause to a trade‐off problem between bias and noise. The problem is seen most evident as blurring of strong illumination features. In particular, this blurring erodes fine structures and sharp lines prominent in caustics. To address this problem, we introduce a photon mapping algorithm based on nonlinear anisotropic diffusion. Our algorithm adapts according to the structure of the photon map such that smoothing occurs along edges and structures and not across. In this way, we preserve important illumination features, while eliminating noise. We demonstrate the applicability of our algorithm through a series of tests. In the tests, we evaluate the visual and computational performance of our algorithm comparing it to existing popular algorithms.
Adaptive Surface Texture Synthesis Using Round‐Shaped Neighbourhoods
Authors: Chen D. , Dong F. 
Published: September 2008

Abstract This paper presents a novel surface texture synthesis method, which is capable of producing high‐quality results by performing the synthesis within an effective multi‐resolution scheme using an adaptive texture similarity metric. Compared with related works, our method allows us to directly carry out multi‐resolution synthesis without involving complicated operations such as mesh hierarchy and partitioning on the target surface. Also, the adaptive similarity metric focuses on measuring texture properties at different scales ranging from local to global, allowing for consistency within differently‐sized texture structures. Further, with the introduced round shaped neighbourhoods, we can save considerable amount of computation for the surface texture synthesis over variable texture directions. Experimental results are provided and comparisons are made against other latest works.
Tensor Clustering for Rendering Many‐Light Animations
Authors: Hašan Miloš , Velázquez‐Armendáriz Edgar , Pellacini Fabio , Bala Kavita 
Published: September 2008

AbstractRendering animations of scenes with deformable objects, camera motion, and complex illumination, including indirect lighting and arbitrary shading, is a long‐standing challenge. Prior work has shown that complex lighting can be accurately approximated by a large collection of point lights. In this formulation, rendering of animation sequences becomes the problem of efficiently shading many surface samples from many lights across several frames. This paper presents a tensor formulation of the animated many‐light problem, where each element of the tensor expresses the contribution of one light to one pixel in one frame. We sparsely sample rows and columns of the tensor, and introduce a clustering algorithm to select a small number of representative lights to efficiently approximate the animation. Our algorithm achieves efficiency by reusing representatives across frames, while minimizing temporal flicker. We demonstrate our algorithm in a variety of scenes that include deformable objects, complex illumination and arbitrary shading and show that a surprisingly small number of representative lights is sufficient for high quality rendering. We believe out algorithm will find practical use in applications that require fast previews of complex animation.
An Analysis of the In‐Out BRDF Factorization for View‐Dependent Relighting
Authors: Mahajan Dhruv , Tseng Yu‐Ting , Ramamoorthi Ravi 
Published: September 2008

AbstractInteractive rendering with dynamic natural lighting and changing view is a long‐standing goal in computer graphics. Recently, precomputation‐based methods for all‐frequency relighting have made substantial progress in this direction. Many of the most successful algorithms are based on a factorization of the BRDF into incident and outgoing directions, enabling each term to be precomputed independent of viewing direction, and re‐combined at run‐time. However, there has so far been no theoretical understanding of the accuracy of this factorization, nor the number of terms needed. In this paper, we conduct a theoretical and empirical analysis of the BRDF in‐out factorization. For Phong BRDFs, we obtain analytic results, showing that the number of terms needed grows linearly with the Phong exponent, while the factors correspond closely to spherical harmonic basis functions. More generally, the number of terms is quadratic in the frequency content of the BRDF along the reflected or half‐angle direction. This analysis gives clear practical guidance on the number of factors needed for a given material. Different objects in a scene can each be represented with the correct number of terms needed for that particular BRDF, enabling both accuracy and interactivity.
Real‐time Shading with Filtered Importance Sampling
Authors: Křivánek Jaroslav , Colbert Mark 
Published: September 2008

AbstractWe propose an analysis of numerical integration based on sampling theory, whereby the integration error caused by aliasing is suppressed by pre‐filtering. We derive a pre‐filter for evaluating the illumination integral yielding filtered importance sampling, a simple GPU‐based rendering algorithm for image‐based lighting. Furthermore, we extend the algorithm with real‐time visibility computation. Free from any pre‐computation, the algorithm supports fully dynamic scenes and, above all, is simple to implement.
Ptex: Per‐Face Texture Mapping for Production Rendering
Authors: Burley Brent , Lacewell Dylan 
Published: September 2008

AbstractExplicit parameterization of subdivision surfaces for texture mapping adds significant cost and complexity to film production. Most parameterization methods currently in use require setup effort, and none are completely general. We propose a new texture mapping method for Catmull‐Clark subdivision surfaces that requires no explicit parameterization. Our method, Ptex, stores a separate texture per quad face of the subdivision control mesh, along with a novel per‐face adjacency map, in a single texture file per surface. Ptex uses the adjacency data to perform seamless anisotropic filtering of multi‐resolution textures across surfaces of arbitrary topology. Just as importantly, Ptex requires no manual setup and scales to models of arbitrary mesh complexity and texture detail. Ptex has been successfully used to texture all of the models in an animated theatrical short and is currently being applied to an entire animated feature. Ptex has eliminated UV assignment from our studio and significantly increased the efficiency of our pipeline.
Lazy Solid Texture Synthesis
Authors: Dong Yue , Lefebvre Sylvain , Tong Xin , Drettakis George 
Published: September 2008

AbstractExisting solid texture synthesis algorithms generate a full volume of color content from a set of 2D example images. We introduce a new algorithm with the unique ability to restrict synthesis to a subset of the voxels, while enforcing spatial determinism. This is especially useful when texturing objects, since only a thick layer around the surface needs to be synthesized. A major difficulty lies in reducing the dependency chain of neighborhood matching, so that each voxel only depends on a small number of other voxels.Our key idea is to synthesize a volume from a set of pre‐computed 3D candidates, each being a triple of interleaved 2D neighborhoods. We present an efficient algorithm to carefully select in a pre‐process only those candidates forming consistent triples. This significantly reduces the search space during subsequent synthesis. The result is a new parallel, spatially deterministic solid texture synthesis algorithm which runs efficiently on the GPU.Our approach generates high resolution solid textures on surfaces within seconds. Memory usage and synthesis time only depend on the output textured surface area. The GPU implementation of our method rapidly synthesizes new textures for the surfaces appearing when interactively breaking or cutting objects.
Geometry‐Aware Framebuffer Level of Detail
Authors: Yang Lei , Sander Pedro V. , Lawrence Jason 
Published: September 2008

AbstractThis paper introduces a framebuffer level of detail algorithm for controlling the pixel workload in an interactive rendering application. Our basic strategy is to evaluate the shading in a low resolution buffer and, in a second rendering pass, resample this buffer at the desired screen resolution. The size of the lower resolution buffer provides a trade‐off between rendering time and the level of detail in the final shading. In order to reduce approximation error we use a feature‐preserving reconstruction technique that more faithfully approximates the shading near depth and normal discontinuities. We also demonstrate how intermediate components of the shading can be selectively resized to provide finer‐grained control over resource allocation. Finally, we introduce a simple control mechanism that continuously adjusts the amount of resizing necessary to maintain a target framerate. These techniques do not require any preprocessing, are straightforward to implement on modern GPUs, and are shown to provide significant performance gains for several pixel‐bound scenes.
Rendering Trees with Indirect Lighting in Real Time
Authors: Boulanger K. , Bouatouch K. , Pattanaik S. 
Published: September 2008

AbstractHigh quality lighting is one of the challenges for interactive tree rendering. To this end, this paper presents a lighting model allowing real‐time rendering of trees with convincing indirect lighting. Rather than defining an empirical model to mimic lighting of real trees, we work at a lower level by modeling the spatial distribution of leaves and by assigning them probabilistic properties. We focus mainly on precise low‐frequency lighting that our eyes are more sensitive to and we add high‐frequency details afterwards. The resulting model is efficient and simple to implement on a GPU.
Feature‐guided Image Stippling
Authors: Kim Dongyeon , Son Minjung , Lee Yunjin , Kang Henry , Lee Seungyong 
Published: September 2008

AbstractThis paper presents an automatic method for producing stipple renderings from photographs, following the style of professional hedcut illustrations. For effective depiction of image features, we introduce a novel dot placement algorithm which adapts stipple dots to the local shapes. The core idea is to guide the dot placement along ‘feature flow’ extracted from the feature lines, resulting in a dot distribution that conforms to feature shapes. The sizes of dots are adaptively determined from the input image for proper tone representation. Experimental results show that such feature‐guided stippling leads to the production of stylistic and feature‐emphasizing dot illustrations.
iCheat: A Representation for Artistic Control of Indirect Cinematic Lighting
Authors: Obert Juraj , Křrivánek Jaroslav , Pellacini Fabio , Sýkora Daniel , Pattanaik Sumanta 
Published: September 2008

AbstractThanks to an increase in rendering efficiency, indirect illumination has recently begun to be integrated in cinematic lighting design, an application where physical accuracy is less important than careful control of scene appearance. This paper presents a comprehensive, efficient, and intuitive representation for artistic control of indirect illumination. We encode user's adjustments to indirect lighting as scale and offset coefficients of the transfer operator. We take advantage of the nature of indirect illumination and of the edits themselves to efficiently sample and compress them. A major benefit of this sampled representation, compared to encoding adjustments as procedural shaders, is the renderer‐independence. This allowed us to easily implement several tools to produce our final images: an interactive relighting engine to view adjustments, a painting interface to define them, and a final renderer to render high quality results. We demonstrate edits to scenes with diffuse and glossy surfaces and animation.
Compact, Fast and Robust Grids for Ray Tracing
Authors: Lagae Ares , Dutré Philip 
Published: September 2008

AbstractThe focus of research in acceleration structures for ray tracing recently shifted from render time to time to image, the sum of build time and render time, and also the memory footprint of acceleration structures now receives more attention. In this paper we revisit the grid acceleration structure in this setting. We present two efficient methods for representing and building a grid. The compact grid method consists of a static data structure for representing a grid with minimal memory requirements, more specifically exactly one index per grid cell and exactly one index per object reference, and an algorithm for building that data structure in linear time. The hashed grid method reduces memory requirements even further, by using perfect hashing based on row displacement compression. We show that these methods are more efficient in both time and space than traditional methods based on linked lists and dynamic arrays. We also present a more robust grid traversal algorithm. We show that, for applications where time to image or memory usage is important, such as interactive ray tracing and rendering large models, the grid acceleration structure is an attractive alternative.
Combining Confocal Imaging and Descattering
Authors: Fuchs Christian , Heinz Michael , Levoy Marc , Seidel Hans‐Peter , Lensch Hendrik P. A. 
Published: September 2008

AbstractIn translucent objects, light paths are affected by multiple scattering, which is polluting any observation. Confocal imaging reduces the influence of such global illumination effects by carefully focusing illumination and viewing rays from a large aperture to a specific location within the object volume. The selected light paths still contain some global scattering contributions, though. Descattering based on high frequency illumination serves the same purpose. It removes the global component from observed light paths. We demonstrate that confocal imaging and descattering are orthogonal and propose a novel descattering protocol that analyzes the light transport in a neighborhood of light transport paths. In combination with confocal imaging, our descattering method achieves optical sectioning in translucent media with higher contrast and better resolution.
Enhancement of Bright Video Features for HDR Displays
Authors: Didyk P. , Mantiuk R. , Hein M. , Seidel H.P. 
Published: September 2008

AbstractTo utilize the full potential of new high dynamic range (HDR) displays, a system for the enhancement of bright luminous objects in video sequences is proposed. The system classifies clipped (saturated) regions as lights, reflections or diffuse surfaces using a semi‐automatic classifier and then enhances each class of objects with respect to its relative brightness. The enhancement algorithm can significantly stretch the contrast of clipped regions while avoiding amplification of noise and contouring. We demonstrate that the enhanced video is strongly preferred to non‐enhanced video, and it compares favorably to other methods.
Free Form Incident Light Fields
Authors: Unger J. , Gustavson S. , Larsson P. , Ynnerman A. 
Published: September 2008

AbstractThis paper presents methods for photo‐realistic rendering using strongly spatially variant illumination captured from real scenes. The illumination is captured along arbitrary paths in space using a high dynamic range, HDR, video camera system with position tracking. Light samples are rearranged into 4‐D incident light fields (ILF) suitable for direct use as illumination in renderings. Analysis of the captured data allows for estimation of the shape, position and spatial and angular properties of light sources in the scene. The estimated light sources can be extracted from the large 4D data set and handled separately to render scenes more efficiently and with higher quality. The ILF lighting can also be edited for detailed artistic control.
Accelerating Ray Tracing using Constrained Tetrahedralizations
Authors: Lagae Ares , Dutré Philip 
Published: September 2008

AbstractIn this paper we introduce the constrained tetrahedralization as a new acceleration structure for ray tracing. A constrained tetrahedralization of a scene is a tetrahedralization that respects the faces of the scene geometry. The closest intersection of a ray with a scene is found by traversing this tetrahedralization along the ray, one tetrahedron at a time. We show that constrained tetrahedralizations are a viable alternative to current acceleration structures, and that they have a number of unique properties that set them apart from other acceleration structures: constrained tetrahedralizations are not hierarchical yet adaptive; the complexity of traversing them is a function of local geometric complexity rather than global geometric complexity; constrained tetrahedralizations support deforming geometry without any effort; and they have the potential to unify several data structures currently used in global illumination.
Urinary incontinence and use of pads – clinical features and need for help in home care at 11 sites in Europe
Authors: Sørbye Liv Wergeland , Finne‐Soveri Harriet , Ljunggren Gunnar , Topinkova Eva , Garms‐Homolova Vjenka , Jensdóttir Anne Birna , Bernabei Roberto ,   for AdHOC Project Research Group
Published: September 2008

Aim:  The aim of this study was to obtain evidenced‐based knowledge about older persons in home care; we conducted a population‐based study at 11 sites in Europe (2001/2002). This article focuses on urinary incontinence and need for help in home care.Methods:  A sample of 4010 respondents 65 years or older were assessed by the Resident Assessment Instrument for Home Care. Urinary incontinence was defined as leakage once a week or more including use of catheters.Results:  A total of 1478 individuals had urinary incontinence, 45% men and 47% women. The use of pads ran from 29% to 52% between the sites. The associates of urinary incontinence were: moderate or severe cognitive impairment, dependency in toileting and other activities of daily living compared with less impaired; urinary infections, obesity and faecal incontinence. Caregivers to persons with urinary incontinence reported burden or stress more often then carers to nonurinary incontinence individuals (OR = 2.2, 95% CI 1.8–2.7).Conclusions:  To enable older people with incontinence to stay at home with a better quality of life, they need caring assistance during toileting on a regular basis.
Effect of Tyr‐MIF‐1 peptides on blood ACTH and corticosterone concentration induced by three experimental models of stress
Authors: Bocheva A. , Dzambazova E. , Hadjiolova R. , Traikov L. , Mincheva R. , Bivolarski I. 
Published: September 2008

Summary 1 Studies, using a wide variety of stressors, have clearly indicated that the pattern of neuroendocrine response is dependent upon the stress stimulus applied. 2 The Tyr‐MIF‐1 family of peptides (Tyr‐MIF‐1s) includes MIF‐1, Tyr‐MIF‐1, Tyr‐W‐MIF‐1 and Tyr‐K‐MIF‐1. These neuropeptides, neuromodulators are able to inhibit the expression of some forms of stress‐induced analgesia. 3 The aim of this study was to compare changes in ACTH and corticosterone (CORT) concentration after various stressors (immobilization, cold and heat), as well as after injection of investigated Tyr‐MIF‐1s peptides. 4 According to our results, hypothalamic‐pituitary‐adrenal (HPA) system was activated by all the stressors applied. Heat and immobilization are stronger stressors, as the exposure of animals to a high ambient temperature and immobilization resulted in the highest rise of plasma ACTH and CORT concentration when compared with cold stress. Moreover, all the investigated peptides from Tyr‐MIF‐1 family, administered after application of stressors, inhibited the elevations in adrenocorticotropic hormone (ACTH) and corticosterone (CORT) plasma concentrations significantly. 5 In conclusion, the various stressors applied seem to induce a different response of the HPA system as judged by quantitative changes in ACTH and CORT release. We suggest that Tyr‐MIF‐1 peptides may possess anti‐stressor effects, as they inhibited stress‐induced rising in two hormones that were investigated.